The Circular Properties of Materials in Landscape Architecture

The Circular Properties of Materials in Landscape Architecture Materialers CirkulĂŚre Egenskaber i Landskabsarkitekturen An analysis and reflection on the extraction use reuse recycle and conversion of GRANITE CLINKER CONCRETE and SANDSTONE and their properties in danish landscape architecture

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Udarbejdet af Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308 2020-2021

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Content 4

Introduction

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Circular economy in Landscape architecture

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Diagram of materials circular life

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Map of material extraction

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Granite

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Clinkers

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Concrete

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Sandstone

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Methods

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Reflections

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References

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Introduction This report will highlight the qualities and challenges of four materials in relation to circular economy. It will investigate the three life cycles of the selected materials - before, during and after construction - and explain their use, possibilities and barriers in landscape architecture.

The purpose of the project is not to compare and conclude which materials are better than others but instead to chart the selected materials, so landscape architects can select materials for pavements on a more informed basis.

The report will shed light on how materials are extracted, processed, manufactured and constructed. This will create an understanding of the earth’s resources, as well as discuss the effect that the construction industry has on the level of CO2-emission. Examples of the possibilities that exist for reuse, recycling and conversion of the materials will be presented, with the aim to inspire innovative thinking and creative use of previously constructed materials, to reduce the use of virgin, raw materials.

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Circular economy in landscape architecture The circular economy is a counterpart to a traditional linear economy where the various related components are made, used and then disposed1. There is a push within the construction industry to reduce the extraction of natural resources by changing our practices, and to reuse and recycle products and materials. As landscape architects, we aim to contribute to a green and sustainable future but, unfortunately, our field plays a large role in the global CO2-account and our natural resources are becoming scarce2. In order to reach the Paris-deal of reducing the CO2-emissions by 70% in 2030, it is necessary to become more sustainable in our way of constructing and planning our cities and landscapes. In Denmark, there is a historically high recycling rate of construction waste, but included in that rate, is a figure of 52% which accounts for construction waste e.g. in road construction. When used in road construction the material will often be degraded to such a state that it becomes difficult to continue the recycling-chain going forward. This will cause a need for production of new products and the extraction of new resources which then breaks the chain of circularity3.

Even though circular economy seems like an intuitive and simple way of managing our resources, there are many complicating factors to consider, and different initiatives that can be done to meet the principles of circular economy. The quality of the material, as well as the technical properties, are important to consider in order to secure a long-lasting project, and thereby prevent less landfill in the future. It is important to implement materials with great potential to be converted into new products, for it to stay in the circular rotation for longer. Furthermore, the various forms of energy consumption that are being created in both extracting, product manufacturing, transporting and maintaining the product also plays an important role in becoming more sustainable. Rules and restrictions in our building standards, are limiting the possibilities of using previously used materials in new projects, and if this is solved, then the construction industry often experience problems of a logistical and economic matter in retaining materials to reuse in a new project4. In order for the construction industry to become more circular in their approaches it is necessary for a standardization of concepts and terminology for circular economy in order to compare and measure the degrees of circularity at both European and International levels5.

By investigating different materials, this report aims to create an overview of the different possibilities and considerations in choosing and handling a product, as well as it’s qualities in staying in the circular rotation for longer, to relieve the pressure on our natural resources.

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Diagram of materials circular life The diagram has been developed through knowledge and studies from the Ellen MacArthur Foundation1, Danish Landscape Architects committee for Circular Economy2 as well as Aarhus Municipality’s catalog for Circular Economy in the building industry47. Selected materials used for pavement will be described according to the properties in the circular rotation before, during and after construction.

The potentials and barriers that occur in these processes will be further investigated. These different aspects of the circular rotation will be explained in the following section.

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Diagrammet er udarbejdet gennem viden og undersøgelser fra Ellen MacArthur Foundation, Danske Landskabsarkitekters udvalg for Cirkulær Økonomi samt Århus Kommunes katalog for Cirkulær Økonomi i byggebranchen. I diagrammet vil udvalgte belægningsmaterialers cirkulære kredsløb blive beskrevet, både inden, under og efter anlæggelse.

Desuden vil potentialer og barriere, der kan opstå i disse processer, blive kortlagt. Definitionerne for de forskellige led i det cirkulære kredsløb, vil blive forklaret i det følgende afsnit.

Raw material extraction

Råstofudvinding

Raw materials have developed over a long period from the earth’s crust and massifs and have been influenced by water, wind and especially ice glaciers. Over time they will decompose into smaller parts, which then form our soil layers and landscapes. Depending on their size, the eroded rocks are referred to as rocks, gravel, sand and clay. Stones are larger pieces of rock and clay the smallest particles that we cannot see with the naked eye. Different raw materials are found in different areas of the earth. In Denmark, the latest ice age has had a great impact on the landscape we have today, and thus also on the deposits of raw materials and the quality of these6. Raw material can both be extracted from land, the coasts and from the seabeds, where different methods are used.

Råmaterialer har udviklet sig over en lang periode fra jordskorpen og masserne og er blevet påvirket af vand, vind og især isgletchere. Over tid nedbrydes de i mindre dele, som derefter danner vores jordlag og landskaber. Afhængigt af størrelse, bliver de eroderede sten beskrevet som, sten, grus, sand og ler. Sten er de store stykker og ler de mindste partikler, som vi ikke kan se med det blotte øje. Forskellige råmaterialer findes i forskellige områder af jorden. I Danmark har den seneste istid haft stor indflydelse på det landskab, vi har i dag, og dermed også på aflejringer af råmaterialer og kvaliteten af disse6. Råmaterialer kan både udvindes fra land, kyster og fra havbunden, hvor forskellige metoder anvendes.

Product manufacturing

Produktfremstilling

The product manufacturing for those products used in Danish landscape projects can be done in many ways. This depends on the different materials, where the material production takes place and what the final products are to be.

Material production often takes place near the extraction site. During material production, some sorting is done to divide the materials by size and quality. The materials can be crushed, cleaved, sawed etc. depending on the final product, and the processing can both be done by manual power, but most often by machinery. The many different types of machinery can be supplied by a range of different energy sources.

Produktfremstillingen for de produkter, der anvendes i danske landskabsprojekter, kan udføres på mange måder.

Dette afhænger af de forskellige materialer, hvor materialeproduktionen finder sted, og hvad de endelige produkter skal ende ud i at være. Produktfremstillingen finder ofte sted nær udvindingsstedet. Under produktfremstillingen foretages en sortering for at opdele materialerne efter størrelse og kvalitet. Materialerne kan knuses, kløves, saves osv. afhængigt af det færdige produkt, og forarbejdningen kan både ske ved håndkraft, men gøres oftest ved brug af maskiner. De mange forskellige typer maskiner kan anvende en række forskellige energikilder.

Product

Produkt

In landscape architecture, different types of pavement with different designs can be used. The finished products can have different expressions depending on the raw material used, so colors and structures can vary greatly. Pavements in Denmark often require a high frost and salt tolerance and the pavements must also be skid-proof7. Certifications and standards, such as DS/EN and the CE mark, control that the products comply with the quality requirements8,9.

Inden for landskabsarkitektur kan der bruges forskellige belægningstyper med forskellige udformninger. De færdige produkter kan have forskelligt udtryk alt efter hvilket råstof der benyttes, så farver og strukturer kan variere meget.

Til belægninger i Danmark stilles der ofte krav om en høj frost- og salttolerance og belægningen skal ligeledes være skridsikker7. Certificeringer og standarder, såsom DS/EN og CE-mærket, er med til at kontrollere, at produkterne overholder kvalitetskravene8,9.

Construction

Anlæggelse

Construction of the product depends on the product itself, but usually a paving is constructed based on Normer og Vejledning for Anlægsarbejde, which have clear guidelines for how different paving stones are to be constructed10. The construction is of great importance for whether a product can be included in a circular rotation, i.e. whether it can be repaired, reused, recycled or converted. If the product is placed in a loose joint, this is very possible. If, on the other hand, the product is cast in concrete or asphalt, which may be due to a need to handle heavy loads, the product becomes more difficult to obtain in the circular rotation. It may be necessary to use machinery and chemicals, which can ultimately be costly11,12. Norms and standards of construction can be a barrier for a more circular mindset of products. This is, for example, if a product is recommended

Anlæggelse af produktet afhænger af selve produktet, men normalt anlægges en belægning ud fra Normer og Vejledning for Anlægsarbejde, der har klare retningslinjer til, hvordan forskellige belægningssten skal anlægges10. Anlæggelsen har stor betydning for, om et produkt kan indgå i et cirkulært kredsløb, det vil sige, om det kan vedligeholdes, genbruges, genanvendes eller genudnyttes. Hvis produktet sættes i en løs fuge, er dette meget muligt. Hvis produktet derimod støbes i beton eller asfalt, hvilket kan skyldes et behov om håndtering af tung belastning, bliver produktet sværere at få i det cirkulære kredsløb. Det kan være nødvendigt at anvende maskiner og kemikalier, hvilket i sidste ende kan blive bekosteligt11,12. Normer for anlæggelse kan være et benspænd for en mere cirkulær tankegang af produkter.

Dette er eksempelvis, hvis et produkt anbefales støbt, frem

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to be cast, rather than placed in a loose joint, without examining alternatives. As the standards should preferably be followed, it does not open up so easily for new methods of constructing products.

for sat i en løs fuge, uden at alternativer undersøges. Da normerne helst skal følges, åbner det ikke så nemt op for nye metoder at anlægge produkterne på.

Project

Projekt

In Denmark, various materials and products are used in landscape projects. Some have a greater historical tradition in Denmark than others, and some can be area-specific anchored. When a project is finished, the different products have various lifespans. This is influenced by the conditions of which the products are placed, their possibilities of repair and maintenance, but mostly by the quality of the product. When a project site is to be redesigned or demolished, it is decided whether it is possible to repair, reuse, recycle or convert the product based on its circular properties.

I Danmark anvendes forskellige materialer og produkter i landskabsprojekter. Nogle har en større historisk tradition i Danmark end andre, og andre kan være områdespecifikke forankrede. Når et projekt er færdigt, har de forskellige produkter forskellige levetider. Dette påvirkes af de betingelser, som produkterne placeres under, deres muligheder for reparation og vedligeholdelse, men for det meste af produktets kvalitet. Når et projektsted skal redesignes eller ryddes, fremstår materialets cirkulære egenskaber, det vil sige om det er muligt at vedligeholde, genbruge, genanvende eller genudnytte produktet.

Repair

Vedligeholdelse

Repair is the inner circle of the diagram of a product’s circular rotation. If a product is easy to repair and maintain the project’s lifespan can be extended. The maintenance of the different products can include cleaning with high-pressure washer and chemicals and filling up joints to maintain a solid and durable pavement. If parts can be replaced and repaired instead of the whole surface, the costs will be lower, and the product will stay circular longer. Furthermore, the extraction of raw materials can be reduced if more products are repaired or maintained. The most sustainable is, therefore, to keep the product in the inner circulation.

Vedligeholdelse er den inderste cirkel af diagrammet for et produkts cirkulære livscyklus. Hvis et produkt er let at reparere og vedligeholde, kan projektets levetid forlænges.

Vedligeholdelsen af de forskellige produkter kan omfatte rengøring med højtryksrenser og kemikalier og opfyldning af fuger for at opretholde en solid og holdbar belægning.

Hvis dele kan udskiftes og repareres i stedet for hele overfladen, bliver omkostningerne lavere, og produktet forbliver cirkulært længere. Desuden kan udvindingen af råmaterialer reduceres, hvis flere produkter repareres eller vedligeholdes. Det mest bæredygtige er derfor at holde produktet i dets inderste cirkulation.

Reuse

Genbrug

When a project needs to be cleared, some of the products on site may be used again. If the products can be used without further manufacturing directly on site or directly in another project, it is called reuse. If a product is reused, it simply needs to be constructed to become part of a new project again, as well as part of a circular rotation. The more times a product can be reused without manufacturing, the longer can it be found in a circular rotation.

Når et projekt skal ryddes kan nogle af produkterne på stedet måske bruges igen. Hvis produkterne kan anvendes uden forarbejdning direkte på stedet eller direkte i et andet projekt, kaldes det genbrug. Hvis et produkt bliver genbrugt, skal det blot anlægges, for igen at blive del af et nyt projekt, og dermed er produktet en del af en cirkulær livscyklus. Jo flere gange et produkt kan genbruges uden forarbejdning, jo længere kan det eksistere i det cirkulære kredsløb.

Recycle

Genanvende

If a product is recycled, it means that it has been manufactured so that it appears as a different product than the original. For example, it may include cutting or other ways of adjusting it to fit a new pavement pattern. After the product has been adapted or otherwise changed for a new purpose, the product must be constructed to eventually be part of a new project. The product is still part of the circular rotation, but not as the original product that was first manufactured, but now as a recycled product that can then again be repaired, reused and perhaps recycled. When a product is recycled, it may have shortened its circular lifespan, as cuts and adjustments will eventually cause the product to reach its minimum volume, and thus can no longer be reused and recycled.

Hvis et produkt er genanvendt betyder det, at det er blevet bearbejdet, så det fremstår som et andet produkt end originalt. Det kan for eksempel indbefatte tilskæringer, således, at det kan indgå i et nyt belægningsmønster. Efter produktet er tilrettet eller på anden vis ændret til et nyt formål, skal produktet igen anlægges for til sidst at indgå i et nyt projekt.

Produktet indgår stadig i den cirkulære livscyklus, men ikke som det originale produkt, som først blev fremstillet, men nu som et genanvendt produkt, der herefter kan vedligeholdes, genbruges og måske genanvendes igen. Når et produkt genanvendes kan det have forkortet sin cirkulære levetid, da tilskæringer og tilpasninger til sidst vil medføre, at produktet når sin mindste volumen, og dermed ikke længere kan genbruges og genanvendes.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Conversion

Genudnytte

The outermost circle in the diagram is conversion, where the product is crushed into small fractions. These can be used as a by-product, for example as aggregate to a new product or a base layer. This requires some sort of product manufacturing at a factory, after which the finished product is constructed. Alternatively, the crush can also provide shards that can be used for pavements. The fractions after crushing will be so small that they may be difficult to repair, reuse and recycle unless used in a completely new product with its own circular rotation.

Den yderste cirkel i diagrammet er genudnyttelse, hvor produktet bliver nedknust til små fraktioner. Disse kan bruges som et biprodukt, for eksempel som tilslag til nyt produkt eller til bærelag. Dette kræver en form for produktfremstilling på en fabrik, hvorefter det færdige produkt anlægges.

Alternativ kan nedknusningen også give skærver, der kan bruges til belægning. Fraktionerne efter nedknusning vil være så små, at de kan være vanskelige at vedligeholde, genbruge og genanvende, med mindre de bruges i et helt nyt produkt, der få sin egen cirkulære livscyklus.

Depositing

Deponering

A product ends up in a deposit, when it can no longer be part of a circular rotation. This happens when it can then no longer be repaired, reused, recycled or converted. Attempts must, of course, be made to avoid this to further keep products in a circular rotation, but disposal can be necessary due to contamination in the product, among other things. If there are any contaminants, the depositing will take place at an environmentally approved facility13. The depositing can also be of residual materials from production. Then the disposal can take place on, for example, fields if the residual material is not polluted.

Når et produkt ender til deponi skyldes det, at det ikke længere kan indgå i et cirkulært kredsløb. Det betyder, at et produkt ikke længere kan vedligeholdes, genbruges, genanvendes eller genudnyttes. Det skal selvfølgelig forsøges undgået, for at beholde produkter i et cirkulært kredsløb, men deponering kan blandt andet skyldes forurening i produktet. Hvis der er forurening, vil deponeringen ske på et miljøgodkendt anlæg13. Deponeringen kan også være af restmaterialer fra produktionen. Her kan deponeringen foregå på for eksempelvis marker, hvis restmaterialet ikke er forurenende.

Energy consumption

Energiudledning

During the life of a product, energy will be emitted. It can be during the extraction, product manufacturing or when constructed, but to a large extent also from the transport between the different stages of a product’s life in the circular rotation. In this report, energy has primarily been elucidated by CO2-emission, which can be difficult to account for.

However, it is still a necessary consideration when analysing the circular properties and possibilities of products, as it may help to support decisions in the choice of materials and products for future projects.

I løbet af et produkts livscyklus vil der blive udledt energi.

Det kan være i udvindingen, produktfremstillingen eller anlæggelse, men i høj grad også fra den transport, der ligger mellem alle de forskellige stadier og trin i et produkts livscyklus. I denne rapport har energi primært været belyst ved CO2-udledning, hvilket kan være vanskeligt at redegøre for. Dog det er stadig en nødvendig overvejelse, når produkters cirkulære egenskaber og muligheder kortlægges, da det kan være med til at understøtte beslutninger om valg af materialer og produkter til fremtidige projekter.

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Our ressources on earth need consideration when designing and construction our future landscapes. At Prøvestenen in Copenhagen large mountains of aggregates are waiting to be used utilized in a new context.

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Map of material extraction

Granite Sweden

200 km

Sandstone England

1400 km

Clinker Holland

750 km

2820 km Portugal

Materials can be extracted and transported from many different areas in the world, and end up in a landscape project in Denmark. The transportation varies and can be by truck, container ship and freight train. The transportation is illustrated by different icons, and shows the different means of transportation from the extraction site to the final distination in the harbour of Copenhagen. Even though some materials are transported over long distances they can still have a lower CO2-emission than some materials extracted and manufactured closer to or in Denmark.

Depending on where the materials are extracted, it can have an impact on the technical properties on the final product.

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Granite

Denmark

Concrete Clinker

Bornholm

Granite

250 km 7210 km

6650 km

550 km

Granite Sandstone

China

India

Germany

Sandstone

Granite Sandstone Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Granite

Granit

Granite originates from magma created by volcanic activity. The granite from Bornholm, Denmark, is among the oldest due to its creation about 1.5 billion years ago. However, most of the granite used in the Danish construction industry comes from Portugal in particular, followed by Sweden, China and India. This is even though the Danish granite has proven to be the most suitable for our Nordic climate due to its frost and salt resistant, as well as non-slip properties. There are many processing options of granite, which depends on the desired aesthetics and functionality. The color scheme varies from red and yellow to blue, green, gray and almost black. In landscape architecture, granite will typically be designed as paving stones, cobblestones and tiles, but can also be produced for more specialized products. Granite requires almost no maintenance, is very robust and has a very long life span. There is a great opportunity to recycle granite, as it is often stored or resold when a project area is renewed. Recycling granite is possible, but it is not as often seen in landscape projects as reusing. In addition, it can also be converted as granite aggregates by crushing, and thus a long life span in the circular circuit.

Granit stammer fra magma skabt af vulkansk aktivitet, og granitten fra Bornholm, Danmark, er blandt de ældste på grund af dens skabelse for cirka 1,5 milliarder år siden. Dog kommer størstedelen af granitten brugt i den danske anlægsbranchen fra særligt Portugal og dernæst Sverige, Kina og Indien. Dette er selvom den danske granit har vist sig at være den mest velegnede til vores nordiske klima på grund af dens frost- og saltbestandige, samt skridsikre egenskaber. Der er mange forarbejdningsmuligheder af granit, hvilket afhænger af den ønskede æstetik og funktionalitet, og farveskemaet varierer fra rød og gul til blå, grøn, grå og næsten sort. I landskabsarkitekturen vil granit typisk udformes som chaussesten, brosten og fliser, men kan også produceres til mere specialiserede produkter. Granit kræver næsten ingen vedligeholdelse, er meget robust og har en meget lang levetid. Der er stor mulighed for at genbruge granit, da den ofte opbevares eller videresælges, når et projektområde fornyes. Genanvendelse af granit er muligt, men det ses ikke så ofte i landskabsprojekter som genbrug. Desuden kan det også genudnyttes som granitstabil ved knusning, og har dermed en lang levetid i det cirkulære kredsløb.

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 1: Swedish quarry. Mathilde Helmstedt

Photo 2: Manufacturing of cleaved granite. Vinnova

Photo 3: Manufacturing of sawed granite. Vinnova

Photo 4: Cleaved granite. Mathilde Helmstedt

Photo 5: Granite tiles.

A quarry in Sweden where the granite is extracted (photo 1).

After extraction is the different granite products manufactured. This can for instanse be done by cleaving (photo 2) or by a diamond saw (photo 3). The outcome can have various expression and can be both rough as the cleaved surface (photo 4) or more even as a sawed and jet-burned surface (photo 5). The result of the manufactured granite products can furthermore vary in size, and for instance beCaspersen made into cobblestone (photo 6). cxv308 17 Alberte Borup, bls326 & Nina Trock-Jansen,

Photo 5: Pile of cobblestone.

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Raw material extraction

Råstofudvinding

Granite originates from magma of volcanic activity and the granite from Bornholm, Denmark, is among the most ancient one, due to its creation from approximately 1.5 billion years ago12. As the magma cools and solidifies, a massive mass of minerals is formed, which we today define as granite. These minerals are crystallised, sharp and very compressed which gives granite the qualities they have today6. The extraction of the granite starts by removing soil and planting from the rocks. Afterwards, the area is investigated to locate the vertical and horizontal layers that are within the rock. Then the extraction of the granite can start. The process of extraction varies and can be done by drilling, sawing or exploding. In the quarries on Bornholm, the extraction is done by explosions with a specially fabricated dynamite. The dynamite is placed inside drilled holes, that are placed with a 25 centimetres distance14.

Two danish firms who work with and distribute granite are Zurface and Bent Vangsøe Natursten. Of the total amount of granite they sell in Denmark, approximately 50-66% come from quarries in Portugal. The rest is imported from other countries, such as Sweden, China and India. However, Zurface has a monopoly to extract and process granite from the quarries on Bornholm12,15. Their sale of the danish granite is about 15% of their total granite sale12.

Granit stammer fra magma skabt af vulkansk aktivitet, og granitten fra Bornholm, Danmark, er blandt de ældste på grund af dens skabelse for cirka 1,5 milliarder år siden12.

Når magmaen afkøles og størkner, dannes en massiv masse af mineraler, som vi i dag definerer som granit.

Disse mineraler er krystalliserede, skarpe og meget komprimerede, hvilket giver granit de kvaliteter, de har i dag6.

Udvindingen af ​​granitten startes ved at fjerne jord og planter fra klipperne. Derefter undersøges området for at lokalisere de vertikale og horisontale lag, der er i klippen.

Efterfølgende kan udvindingen af granitten ​​ starte. Udvindingsprocessen varierer og kan udføres ved at bore, save eller eksplodere klippeblokkene. I stenbruddene på Bornholm sker udvindingen ved eksplosioner med en specielt fremstillet dynamit. Dynamitten placeres i borede huller, der er placeres med en afstand på 25 centimeter14.

To danske firmaer, der arbejder og forhandler med granit, er Zurface og Bent Vangsøe Natursten. Af den samlede mængde granit, de sælger i Danmark, kommer cirka 50-66% fra stenbrud i Portugal. Resten importeres fra andre lande, såsom Sverige, Kina og Indien. Zurface har dog monopol på at udvinde og forarbejde granit fra stenbruddene på Bornholm12,15. Deres salg af den danske granit udgør ca. 15% af deres samlede granitsalg12.

Produkt manufacturing

Produktfremstilling

The product manufacturing and processing of granite products are often done near the extraction location. There are great possibilities when processing granite which depends on the desired aesthetics and functionalities. The following are the most common production methods in landscape architecture. Cleaved granite is hard-wearing, skidproof and suitable for heavy traffic, but the surface is not very even. Another process is to saw the material with diamond saws which will result in a more even, smooth surface. The granite can then be jet-burned, where the surface will be slightly ruptured through heating, and be even and skidproof. The sawed surface can furthermore be dressed by hammering steel blades into the granite to make the surface less slippery and more skidproof too16.

The production in Denmark uses recycled water and renewable energy, wherein for instance China the power supply is mostly based on fossil fuels17. The production outside of Denmark is in general more difficult to account for, due to difficulties in monitoring it and a lack of reliability12.

Produktfremstillingen og forarbejdningen af granitproduk​​ ter sker ofte nær udvindingsstedet. Der er mange forarbejdningsmuligheder af granit, hvilket afhænger af den ønskede æstetik og funktionalitet. Følgende er de mest almindelige produktionsmetoder i landskabsarkitektur. Kløvet granit er slidstærk, skridsikker og velegnet til tung trafik, men overfladen er ikke særlig jævn. En anden forarbejdningsmulighed er at save materialet med diamantsave, hvilket vil resultere i en mere jævn, glat overflade. Granitten kan derefter jetbrændes, hvor overfladen sprænges let gennem opvarmning, og vil derefter fremstå jævn og skridsikker. Den savede overflade kan desuden stokhugges for at gøre overfladen mindre glat og mere skridsikker16. Produktionen i Danmark anvender genanvendt vand og vedvarende energi, hvor strømforsyningen f.eks. i Kina hovedsagelig er baseret på fossile brændstoffer17. Produktionen uden for Danmark er generelt sværere at redegøre for, hvilket skyldes vanskeligheder med kontrol og manglende pålidelighed12.

Product

Produkt

When granite is used in a landscape project the lifespan of the product is expected to be almost infinite. Granite is often used as cobblestone and flagstones, but can also be produced to more specialized products. It is possible to form the material into a wide range of shapes and sizes and the colour scheme varies from red and yellow to blue, green, grey and almost black. Granite being a natural product will create colour variation, even though a larger block, can seem like a uniform colour.

Når granit bruges i et landskabsprojekt forventes produktets levetid at være næsten uendeligt. Granit bruges ofte som chaussesten, brosten og fliser, men kan også produceres til mere specialiserede produkter. Det er muligt at forarbejde materialet til en lang række former og størrelser, og farveskemaet varierer fra rød og gul til blå, grøn, grå og næsten sort. Da granit er et naturprodukt vil der forekomme farvevariation, selvom en større blok kan syne ensfarvet.

I Danmark finder vi normalt portugisiske eller kinesiske

The Circular Properties of Materials in Landscape Architecture 2020-2021

In Denmark, we usually find Portuguese or Chinese products in construction, even though the danish granite has been proved to be the most suitable for our nordic climate, due to its frost and salt resistant and skid-proof properties.

This is due to the lower costs of the materials outside of Denmark - even when considering that the material is being transported from abroad12,15. Furthermore, the Danish granite is CE-certificated with the highest level of quality; E (Extra aggressive)6. In other countries, they have different use or no use of certification, which makes it problematic to certify the granite from abroad. However, imported granite is still mainly used in danish landscaping12.

produkter under anlæggelse af et projekt, selvom den danske granit har vist sig at være den mest velegnede til vores nordiske klima på grund af dens frost- og saltbestandige, samt skridsikre egenskaber. Dette skyldes de lavere omkostninger ved materialerne uden for Danmark - selv når man overvejer, at materialet transporteres fra udlandet12,15. Desuden er den danske granit CE-certificeret med det højeste kvalitetsniveau; E (ekstra aggressiv)6. I andre lande har de forskellige anvendelser, eller ingen brug af certificering, hvilket gør det problematisk at certificere granitten fra udlandet. Imidlertid anvendes importeret granit stadig hovedsageligt i dansk landskabsarkitektur12.

Construction

Anlæggelse

Granite products are mostly placed in sand, but it happens that it is cast in concrete if the pavement is exposed to heavy traffic. When cast in concrete, the product becomes more difficult to recycle.

The thicker a granite tile, the more steady will the surface be, and thereby last longer12. However, thick granite tiles will be quite heavy and more difficult to handle, to a pavior.

Granitprodukter sættes for det meste i sand, men det sker, at det støbes i beton, hvis belægningen udsættes for tung trafik. Ved støbning i beton bliver produktet sværere at genbruge eller genanvende. Jo tykkere en granitflise er, des mere stabil vil belægningen være og derved vare længere12. Dog vil tykke granitfliser være ret tunge og sværere at håndtere for en anlægsgartner.

Project

Projekt

Granite has been used in Denmark for hundreds of years and today one can find curbstones and cobblestones almost everywhere12. The project on Christiansborg Slotsplads is an example of how granite is used in multiple ways that create different expressions. Cobblestone and flagstones in granites are used as paving, and big granite balls surround the square18.

Granit har været brugt i Danmark i hundrede år, og i dag kan man finde kantsten, chaussesten og brosten næsten overalt12. Projektet på Christiansborg Slotsplads er et eksempel på, hvordan granit kan bruges på flere måder, hvilket skaber forskellige udtryk. Brosten og bordursten i granit bruges som belægning, og store granitkugler omgiver pladsen18.

Repair

Vedligeholdelse

Granite requires almost no maintenance, which is especially valid for the nordic granite. In Chinese and Portuguese granite, some amount of metal can occur, which influences the colour of the granite over time. This can influence some aesthetic values but does not affect the quality of the granite. If the granite needs maintenance it is possible to use a high-pressure washer or some chemicals. Since granite is a very sturdy material, it rarely breaks.

If it occurs it is easier to repair and replace for instance a single granite tile if it’s placed in sand when constructed12.

Granit kræver næsten ingen vedligeholdelse, hvilket især gælder for den nordiske granit. I kinesisk og portugisisk granit kan der forekomme en vis mængde metal, som over tid påvirker granittens farve. Dette kan påvirke nogle æstetiske værdier ved stenen, men vil ikke påvirke granittens kvalitet.

Hvis granitten skal vedligeholdelse, er det muligt at bruge en højtryksspuler eller et udvalg af kemikalier. Da granit er et meget robust materiale bryder det sjældent. Hvis det sker, er det lettere at reparere og udskifte f.eks. en enkelt granitflise, hvis den er sat i en løs fuge, når den anlægges12.

Reuse

Genbrug

Due to granite’s long lifespan, it is easy to reuse, unless it is cast in concrete. If so, it will take more resources and be costly to reuse it. There is a great possibility to reuse granite since it is often placed in storage or resold when a site is redesigned. Though can this solution be more costly than buying new granite due to logistic matters. Some products will even be more costly as reused from the wear and tear which gives a unique, aesthetic value to the material that won’t occur in new materials16. Of Zurface and Bent Vangsøe Natursten’s total sale of granite, two main distributors of granite in Denmark, 5-10% is reused12,15. However, this is not a percentage of the total reused granite in Denmark.

På grund af granittens lange levetid er det let at genbruge, medmindre det er støbt i beton. I så fald vil det kræve flere ressourcer og være dyrt at genbruge det. Der er en stor mulighed for at genbruge granit, da den ofte opbevares eller videresælges, når et projektområde fornyes.

Dog kan denne løsning være dyrere end at købe ny granit på grund af logistiske forhold. Nogle produkter vil endda være dyrere, når de genbruges fra slid, hvilket giver materialet en unik, æstetisk værdi, der ikke forekommer i nye materialer16. 5-10% af Zurface og Bent Vangsøe Natursten, to større leverandørers, samlede salg af granit er genanvendt granit12,15. Dette er dog ikke en procentdel af den samlede genanvendte granit i Danmark.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Recycle

Genanvende

Recycling granite is possible, but it is not seen as often in landscape projects as reusing. It can be costly and more logistically difficult, than buying a new product. However, smaller adjustments on e.g. curbstone can be done directly on the project site to fit a new design proposal. New methods have also shown that it is possible to recycle old cobblestones that have been covered by asphalt to regain its purpose. This is done by cutting 15-30 mm of the top surface off the cobblestones and is, therefore, a quite simple way of recycling the product. If there is a need for chemicals in the process of cleaning the granite it is estimated that the product is not worth recycling12. Another example of recycling granite pavements is e.g. seen on Christiansborg Slotsplads, where old, curved granite tiles have been cut to adjust the new pavement design19.

Genanvendelse af granit er muligt, men det ses ikke så ofte i landskabsprojekter som genbrug. Det kan være dyrt og mere logistisk vanskeligt end at købe et nyt produkt.

Dog kan mindre justeringer på f.eks. kantsten gøres direkte på projektstedet for at tilpasse et nyt designforslag.

Nye metoder har også vist, at det er muligt at genanvende gamle brosten, der er blevet dækket af asfalt for igen at genvinde brostenenes formål. Dette gøres ved at skære 15-30 mm af den øverste overflade af brostenen, hvilket derfor er en ganske enkel måde at genanvende produktet på. Hvis der er behov for kemikalier under rensningen af granitten, anslås det, at produktet ikke er værd at genanvende12. Et andet eksempel på genanvendelse af granitbelægninger er f.eks. set på Christiansborg Slotsplads, hvor gamle, buede granitfliser og bordursten er tilskåret for at passe til det nye belægningsmønster19.

Conversion

Genudnytte

Granite can be used as base course aggregate through crushing. It is estimated that 2% of the Danish granite production ends up crushed12. Granite can also be crushed into stone chippings, that can be used for pavements.

However, this can be problematic, if there is a small quantity of pre-used granite or a too big colour variation to create a homogeneous surface. Granite chippings are therefore often made from new granite, even though there is a potential of using pre-used granite, due to its resistant quality e.g. its long lifespan15.

Granit kan bruges som granitstabil ved knusning. Det anslås, at 2% af den danske granitproduktion ender knust12.

Granit kan også knuses til granitskærver, der kan bruges til belægninger. Dette kan imidlertid være problematisk, hvis der er et for lille sortiment af tidligere anvendte granitsten eller en for stor farvevariation til at skabe en homogen overflade. Granitskærver fremstilles derfor ofte af ny granit, selvom der er potentiale i at bruge tidligere anvendt granit på grund af dets modstandsdygtige kvalitet, f.eks. dets lange levetid15.

Depositing

Deponiering

Due to granite’s long lifespan, the material will continue its circular life cycle. The only depositing of granite is the sludge that is left when cutting the granite in the material production. This is often deposited on fields since it is not polluting12.

På grund af granits lange levetid fortsætter materialet sin cirkulære livscyklus. Det eneste deponi af granit er slammet, der er tilbage, når granitten skæres ved materialefremstillingen.

Dette deponeres ofte på marker, da det ikke er forurenende12.

Energy consumption

Energiudledning

Vinnova is a Swedish innovation authority that has made a life cycle analysis for Swedish and Chinese granite among other materials. From extraction to construction, they conclude that the greatest CO2 load for the Chinese granite is during transportation. Furthermore, the electricity supply in China has a major impact, as this is primarily based on fossil fuels, as mentioned earlier. A Chinese jet-fired granite tile emits almost 200 kg CO2/m2 for both production and transportation to Sweden. For Swedish granite, it is primarily material manufacturing that emits the largest part of the CO2-emission. They have calculated that a jetfired granite tile from Sweden emits 30 kg CO2/m2 with production and transportation to Sweden included17.

The transport to Denmark takes place from the Swedish quarries by truck, whereas from the Portuguese, Chinese and Indian it also includes container ships. From the quarries on Bornholm, the transportation is both by truck and ships12.

Vinnova er en svensk innovationsmyndighed, der har lavet en livscyklusanalyse for blandt andet svensk og kinesisk granit. Fra udvinding til anlæggelse af den kinesiske granit konkluderer de, at den største CO2-belastning sker under transporten. Ydermere har elforsyningen i Kina en stor påvirkning, da den primært er baseret på fossile brændstoffer, som tidligere nævnt. En kinesisk jetbrændt granitflise udleder næsten 200 kg CO2 / m2 til både produktion og transport til Sverige. For svensk granit er det primært produktfremstillingen, der udleder den største del af CO2-udledningen. De har beregnet, at en jetbrændt granitflise fra Sverige udleder 30 kg CO2 / m2 med produktion og transport til Sverige inkluderet17. Transporten til Danmark foregår fra de svenske stenbrud med lastbil, mens den fra de portugisiske, kinesiske og indiske også indbefatter containerskibe. Fra stenbruddene på Bornholm foregår transporten både med lastbil og skib12.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Price range: 444-1157 kr./m2 Dimensioning

8 cm granite stone 3 cm levelling course

12 cm bearing course

17 cm subbase

A 8 cm granite stone for a sqaure that rarely is exposed to trucks or other heavy traffic load (traffic class T1) should have the specified dimensions. Crushed, converted granite can be used as an alternative to virgin materials for the levelling course. The subbase layer is increased from 15 cm to 17 cm to reach the dimensions for construction on a foundation with frost risks. For heavier traffic class, it is recommended that joints, leveling courses and base layers are made of bonded materials in the form of concrete or asphalt10. However, this will make it difficult to reuse, recycle and converte the granite in other projects, since the stones have to undergo cleaning processes through machines and chemicals.

Dimensionering En 8 cm granitsten som anlægges på en mindre plads, der sjældent er udsat for større køretøjer som lastbilstrafik (trafikklasse T1) vil have de angivede dimensioneringer.

I bærelaget kan der bruges nedknust, genudnyttet granit, som alternativ til jomfruelige materialer til stabilgrus.

Bundsikringslaget øges fra 15 cm til 17 cm for at nå dimensionerne for anlæggelse på forstivlsom bund. For tungere trafikklasse anbefales det, at fuger, afretningslag og bærelag udføres i bundne materialer i form af beton eller asfalt10. Dette vil dog gøre det svært genbruge, genanvende og genudnytte granitten i andre sammenhænge, da man i så fald skal benytte maskiner og kemikalier for at rense stenen.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Photo 1: Christiansborg Slotsplads, detailed pavement plan. LYTT

Photo 2: Christiansborg Slotsplads, recycled granite tiles. LYTT

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 3: Christiansborg Slotsplads, reused cobblestones. LYTT

Photo 4: Christiansborg Slotsplads. LYTT

An example of reusing and recycling granite can be found at Christiansborg Slotsplads by LYTT. A detailed plan have been made to get an overview of where to place the many different stones (photo 1). Granite tiles have been cut to fit the new pavement design (photo 2) and reused cobblestone from previosly project are placed in sand (photo 3). The final project is an example of the different ways of keeping materials in its circular life cycle (photo 4).

Andreas Steenbjergs Plads by SLA is another exsample of reusing granite (photo 5). Pre-used granite that was placed in a mosaic pavement design at the site (picture 6) have been moved and now tak part in the new pavement design (picture 7).

Photo 5: Andreas Steenbjergs Plads. SLA

23 Photo 7: Andreas Steenbjergs Plads, reused granite. SLA

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

Photo 6: Andreas Steenbjergs Plads, pre-used granite. SLA

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Clinker

Klinker

Clinkers have a long tradition of being used in the building and construction industry for hundreds of years. They are made of clay, sand and soil minerals, and can come in a wide range of colors depending on the type of clay as well as the firing methods. The firing makes the clinkers resistant to wear and tear, makes it non-slip in frosty weather and ensures its long lifespan. However, it is also the firing that is most energy-intensive in the CO2 accounts, as the clinker must be fired at 1000 °C. Clinkers are rectangular or in another shape that allows them to be laid in a pattern. Furthermore, clinkers have good properties for reusing, and can therefore exist in the circular rotation for a longer period of time. However, this also means that the clinker is rarely used for recycling, reuse or landfill.

Klinker har en lang tradition for at blive anvendt i bygge- og anlægsbranchen i flere hundrede år. Den er skabt af ler, sand og jordmineraler, og kan komme i en bred vifte af farver afhængigt af lertypen og brændingsmetoden. Den hårde brænding gør klinken modstandsdygtig overfor slid, gør den skridsikker i glat vejr samt sikrer dens lange levetid. Dog er det også den hårde brænding, som er allermest energikrævende i CO2regnskabet, da klinken skal brændes ved 1000°C. Klinker skal have en rektangulær form eller lignende form der tillader stenene at blive lagt i et gentaget mønster. Klinker har gode genbrugsmuligheder, og kan derfor eksistere i det cirkulære kredsløb i længere tid. Derfor når klinken sjældent til genanvendelse, genudnyttelse eller deponi.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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The clay is extracted from quarries (photo 1) where the dept of the soil can have an effect of the colour of the clay. It is then brought to the nearby tilework where it is mixed (photo 2) and kneaded in a pug mill where heat and minerals can be added to affect the colour of the clay (photo 3).

Originally, the clay was formed in form using manual power but today only few places uses this method and mostly if a specialised shape is required (photo 4).Today, the clay is mostly formed into the standard measurements by machines (photo 5) . Finally the clay is placed in ovens and fired at more than 1000°C to become clinkers.

Photo 1: Extraction of clay. Vandersanden

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 2. Manufacturing. Vandersanden

Photo 3: Pugmill Vandersanden

Photo 4: Shaping clinker. Pedersen Tegl

Photo 5: Shaping clinker. Vandersanden

27 Photo 6: Firing clinker. Vandersanden

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Raw material extraction

Råstofudvinding

Clinkers are made from nature’s raw materials; clay, sand and other soil minerals. The clay, which has laid in the ground for about 15,000 years, is deposits of traditional rocks and is a mixture of particles from the Swedish and Norwegians mountains, which was brought here by the ice ages20. Over time, rainwater has washed out all soluble material in the deposits and left the natural, clean clay. It is the plasticity of the clay that allows the clay to be shaped and makes it suitable for paving stones16. For the making of clinker, you must use clinker-clay, as it has some qualities that allow it to withstand more pressure. However, in Denmark we only have small quantities left on Bornholm21.

To extract clay, it is necessary to first remove the topsoil, which is set aside for later use. The clay can be found in pure forms underneath and is extracted by excavators22.

Klinker er lavet af naturens egne materialer; ler, sand og andre jordmineraler. Leret, der har ligget i jorden i cirka 15.000 år, stammer fra klippeaflejringer, og er en blanding af partikler fra svenske og norske bjerge, som blev bragt hertil med istiderne20. Gennem tiden har regnvand skyllet alt opløseligt materiale ud i aflejringerne og efterladt det rene, naturlige ler. Det er lerets plasticitet der gør at leret kan formes og gør den velegnet til belægningssten16. Til fremstillingen af klinker, skal man benytte klinkeler, da det har nogle kvaliteter det endelige produkt stærkere. Dog har vi kun små mængder tilbage på Bornholm21. For at udvinde ler er det nødvendigt først at fjerne de øverste jordlag, som vil afsættes til senere brug. Leret udvindes så herefter af gravemaskiner22.

Product manufacturing

Produktfremstilling

All the clay that is extracted will be used in production.

If any flaws occur in the production, the material will be processed again at the factory. At the factory, the clay is kneaded in a pug mill, after which the mixture is heated to 30-45°C by a gas burner or by adding steam23. This kneading breaks the clay’s capillary tube, which will reduce the water uptake of the final clinker to avoid frost bursts21. To get the required shape, the clay mixture is placed in moulds and frames, where it is dried to reduce its moisture content from approximately 24% to 4%. It is then loaded into kilns for high-temperature firing at over 1000°C to give the bricks their exceptional properties, long lifespan and durability24.

The firing also retains the colour of the clinkers, and is then resistant to salting, oil and acid that pavements can be exposed to. The content of iron and limestone in the raw material is determining the colour of the final product, which will result in a range of yellow and red colours. If the burning takes place with a deficit of oxygen, it is possible to force shades from light grey to black. Methods of adding salt or coal to the burning can create a variety of shades16.

Alt ler, der udvindes, vil blive brugt i produktionen. Hvis der opstår fejl i produktionen, behandles materialet igen fra fabrikken og bliver omdannet til et korrekt produkt. På fabrikken æltes leret i en forælter, hvorefter blandingen så opvarmes til 30-45°C med en gasbrænder eller ved damptilsætning23. Denne æltning bryder lerens kapillærrør, hvilket mindsker den endelige klinkes vandoptag for at undgå frostsprængning21. Lerblandingen placeres så i forme og rammer, hvor det tørres for at reducere lerets fugtindhold fra ca. 24% til 4%. Derefter læsses det i ovne til brænding ved temperaturer over 1000°C, som brænder stenene og giver murstene deres lange levetid24. Desuden gør den hårde brænding, at klinken ikke mister farve over tid eller vil blive påvirket af vejsalt, olie og syre som belægninger til tider kan blive udsat for. Indholdet af jern og kalk i råmaterialet bestemmer klinkens endelige farve, som typisk spændender over en række gule og røde nuancer.

Hvis forbrændingen sker med et iltunderskud, er det muligt at fremtvinge nuancer fra lysegrå til sort. Derudover findes der også metoder som tilsætning af salt og kul i forbrændingen, som bruges til at skabe en række forskellige nuancer16.

Product

Produkt

The life expectancy of clinkers is almost indefinitely. The Danish distributor, Klinker Outdoor, are selling products of up to 100 years of age. These are typically from Holland, where there is a longer tradition of using clinkers than in Denmark25. Another distributor, Steffen Sten, refers to clinkers which are more than 700 years old and still very well preserved and in use23.

With an increasing interest in the material, architects and planners using clinker are starting to become more creative with developing and using the product. For instance, by getting dark clay from England or white clay from Germany it is possible to create new colour combinations than from the clay we have in Denmark25. It is then important to be aware of the level to which the clinkers are fired since it is crucial for the anti-skid protection. If the clinker is hard-fired it won’t absorb as much water and

Klinkers levetid nærmer sig uendelig. Ifølge den danske forhandler, Klinker Outdoor, forhandler de gode og velfungerende produkter som er op til 100 år gamle. Disse er typisk fra Holland, hvor der er en længere tradition for at bruge klinker end i Danmark25. En anden dansk forhandler, Steffen Sten, henviser til klinker, der er mere end 700 år gamle og stadig meget velbevarede og fortsat benyttet23.

Med en stigende interesse for materialet begynder arkitekter og planlæggere, at blive mere kreative i udviklingen og brugen af materialet. Ved f.eks. at få mørkt ler fra England eller hvidt ler fra Tyskland, er det nu muligt at skabe nye farvekombinationer end fra det ler, vi har i Danmark25.

Det er dertil vigtigt, at være opmærksom på hvordan klinkerne er brændt, da dette er afgørende for skridsikkerheden. Er klinikeren hårdtbrændt, absorberer den mindre vand og vil derfor være mere skridsikker i frostvejr. Klinker skal have

The Circular Properties of Materials in Landscape Architecture 2020-2021

will then be less slippery in frosty weather. Clinkers are rectangular or in another shape that allows them to be laid in a pattern. They are usually produced in the following measurements; 200-240 mm x 100-120 mm x 45-65 mm26 .

en rektangulær eller lignende form der tillader stenene at blive lagt i et gentaget mønster. Typisk produceres de i følgende formater: 200-240 mm x 100-120 mm x 45-65 mm26.

Construction

Anlæggelse

Clinkers are laid by machines and by hand, and are leveled with string to achieve the desired direction and pattern. With clinker being a natural material, variations in size can occur. It is therefore important to place the clinker with a 3-5 mm joint distance, to erase any variations. Furthermore will the joint protect the clinker from edge damages that can occur if the clinker is laying edge to edge. The joint consists of washed gravel in grain size 0-4 mm, which should be swept thoroughly in between the clinkers. Because of the dimension and shape of the clinker, they have great applicality to be used in many pavement patterns and can even be laid in arches and hills27.

Klinker lægges ved maskiner og håndkraft, og afrettes med snor som kan sikre den ønskede retning og mønster opnås. Da klinker er et naturmateriale, kan der opstå variationer i størrelsen. Derfor er det vigtigt at klinkerne lægges med 3-5 mm fugeafstand, som vil udviske eventuelle variationer. Desuden vil fugen beskytte klinken mod kantskader som kan opstå hvis klinken ligger kant mod kant. Fugen består af vasket grus i kornstørrelse 0-4 mm, som fejes grundigt ned mellem klinkerne.

Klinkers mål og form gør desuden, at de har stor anvendelighed og kan anlægges i mange belægningsmønstre og kan endda lægges i buer og bakker27.

Project

Projekt

The average strength of clinker is about eight times higher than ordinary bricks, and are therefore used when extra high wear resistance and small water absorption is required, e.g. on outdoor sidewalks and stairs28. According to Klinker Outdoor, there has been an increased use and focus on clinkers in urban spaces. Throughout history, clinker has been a very used material but since the 1970’s there hasn’t been traditions of using the material until now, which has resulted in many factories closing in the past 50 years25. Only a few places have been continuing to use clinkers, like in Odense Municipality, where the red/yellow clinker is considered a symbol of Odense29. Klinker Outdoor considers this change in tendency as a sign of users becoming more aware of sustainability, environment and the lifespan of the material25.

Klinkers gennemsnitlige styrke er ca. otte gange højere end almindelige mursten og anvendes derfor ofte steder hvor der kræves ekstra høj slidstyrke og lille vandabsorption, f.eks. på udendørs fortove og trapper28. Ifølge Klinker Outdoor er der stigende fokus på klinker i byrummet. Gennem historien har klinker været et meget brugt materiale, men siden 1970’erne har der ikke været meget tradition for at bruge materialet indtil i dag, og mange teglværk er derfor lukket de sidste 50 år25. Kun få steder, som i Odense Kommune, har fortsat brugt klinker frem til i dag, hvor den røde/gule klinke er et symbol på Odense29. Klinker Outdoor betragter denne ændring som et tegn på, at brugerne bliver mere opmærksomme på bæredygtighed, miljø og materialets levetid25.

Repair

Vedligeholdelse

Clinkers require very low maintenance and there is rarely a need for repair. When clinkers are laid correctly they can last for hundreds of years. If they aren’t laid correctly, e.g. with too much distance between the joints, water and salt can run through to the foundation which in some cases can create frost damages in the clinkers30. Also, if the clinker isn’t burned correctly, the capillary won’t be closed which also can cause frost damages when water then can access the clinker21.

Klinker kræver meget lidt vedligeholdelse, og der er sjældent behov for reparation. Hvis klinker lægges korrekt, kan de fungere i hundreder af år. Hvis de ikke er lagt korrekt, f.eks. med for stor afstand mellem samlingerne kan vand og salt løbe igennem til fundamentet, hvilket i nogle tilfælde kan skabe frostskader i klinkerne30. Er klinken ikke brændt korrekt, lukkes kapillæren i leret ikke, hvilket også kan forårsage frostskader, når vandet så kan løbe ind i klinken21.

Reuse

Genbrug

Clinkers have good properties for reusing in one project to another. When laid in sand, they are easy to pick up without being damaged. Unfortunately, we don’t have a lot of material banksa in Denmark that handles clinkers. Klinker Outdoor receives used clinkers from Holland, where there is a very long tradition of using clinkers in their outdoor spaces, and where they have different nuances and shapes than those we make in Denmark. In Holland, old pavements of clinker can be found under layers of new

Klinker har gode genbrugsmuligheder fra et projekt til et andet. Da de lægges i sand, er de nemme at tage op uden at blive beskadiget. Desværre har vi ikke mange materialebanker i Danmark, som kan opbevare klinkerne. Klinker Outdoor modtager bl.a. brugte klinker fra Holland, hvor der er en meget lang tradition for at bruge klinker i deres udendørs rum, og hvor de har klinker i forskellige nuancer og former end dem, vi laver i Danmark. Nogle steder i Holland kan man finde gamle klinkebelægninger under Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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asphalt, where it has been used as a baselayer. There will typically exist a levelling course between the asphalt and the clinker which will have been protecting the clinker.

It is then possible to collect and reuse them directly25.

nye lag af asfalt, hvor den tidligere belægning har fungeret som et bærelag. Klinkerne og asfalten vil typisk være adskilt af et afretningslag, hvilket har beskyttet klinkerne og gjort det muligt at indsamle dem og genbruge direkte25.

Recycle

Genanvende

It isn’t common to recycle clinkers but it is possible. According to Klinker Outdoor, architects and planners are starting to experiment in new ways of using old clinkers but so far there haven’t been any official records of recycling clinkers25.

Det er ikke almindeligt at genanvende klinker, men det er muligt. Ifølge Klinker Outdoor er arkitekter og planlæggere begyndt at eksperimentere med nye måder at genanvende gamle klinker, men indtil videre findes der ikke nogle officielle resultater herpå25.

Conversion

Genudnytte

It is unusual for clinkers to be crushed down and converted into another purpose. A reason for this is the long lifespan of the clinker - if it has already existed in a project for 50 years, it can usually exist in a new project for another 50 years.

Another important reason is the various financial aspects of converting clinkers. Clinker is an expensive material compared to conventional aggregates such as sand and stones, as there is a longer process behind getting a used clinker cleaned, deposited and crushed. Clinkers rarely decrease in price when used, and may even in some cases increase.

There is therefore rarely an incentive in converting clinkers into aggregates. Should it happen that the clinker was damaged, it can be crushed and converted into smaller fractions.

It can then be used as drainage in plant beds and fields, as it is an organic material created from clay and clean water25.

Det ses sjældent, at klinker knuses ned og genudnyttes i et andet formål. En af årsagerne hertil er klinkens lange levetid - hvis den har eksisteret i et projekt i 50 år, kan den typisk eksistere i et nyt projekt i endnu 50 år. Dertil kommer de økonomiske aspekter. Klinker er et dyrt materiale ift. konventionelle tilslagsmaterialer som sand og sten, da der ligger en længere proces bag at få en brugt klinke renset, deponeret og knust. Klinker falder sjældent som brugt, og kan endda i visse tilfælde endda stige. Derfor er der sjældent incitament til at genudnytte klinker som tilslag.

Skulle det ske, at klinken blev ødelagt, kan den knuses og genudnyttes. Her kan den genudnyttes som dræn i plantebede og på marker, da det er et organisk materiale skabt af ler og rent vand25.

Depositing

Deponering

Due to clinkers lifespan, there still isn’t much result of depositing the material. In Denmark, only 5% of all clinkers are sent to deposit but since it is a pure natural product, it doesn’t compromise the environment23.

På grund af klinkers levetid er der stadig ikke meget resultat af deponering af materialet. I Danmark sendes kun 5% af alle klinker til deponering, men da det er et rent naturprodukt, belaster det ikke miljøet23.

Energy consumption

Energiudledning

When the clay is extracted it is transported directly by truck from the clay quarries to the tilework. The tilework is often situated near the clay quarries to minimise the energy expended in transporting the clay. Tileworks can typically be found near Flensburg Fjord and the Limfjord, where the best clay quality for bricks is found. Unfortunately, there is only one tilework left in Denmark that still produces clay clinkers, where the remaining 24 tileworks produce bricks and tiles25. It is mainly at the tilework where there is the most energy discharge in the production of clinkers. It is particularly drying and firing, where temperatures reach more than 1000°C, that are the most energy-intensive steps. Klinker Outdoor has estimated that producing 250350 m2 of clinkers emits 6-8 tonnes of CO2. It is important to take into account that this is the most energy intensive aspect clinkers operating cycle from extracting to construction as well as its long lifespan of more than 100 years22.

Når leret bliver udvundet bliver det transporteret med lastbil direkte fra lerbruddet til produktionsanlæggene. Produktionsanlæggene er ofte placeret i nærheden af ​​lerbruddene for at minimere den energi, der bruges til at transportere materiale til fabrikken. Teglværker vil typisk kunne findes omkring Flensborg Fjord og Limfjorden, hvor den bedste lerkvalitet til tegl findes. Desværre er der kun ét teglværk tilbage i Danmark, som stadig producerer teglklinker, hvor de resterende 24 producerer mursten og teglsten25. Det er på selve teglværkerne, hvor der er mest energiudladning i klinkens produktionsproces. Særligt tørring og fyring, hvor temperaturerne når op over 1000°C, er de mest energiintensive trin. Klinker Outdoor har beregnet, at produktionen af 250350 m2 klinker udleder 6-8 ton CO2. Det er her vigtigt at tage højde for, at produktionen er det mest energikrævende aspekt i klinkers samlede levetid fra råstofudvinding til anlæggelse, samt klinkens forventede levetid på over 100 år22.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Price range: 255-525 kr./m2 Dimensioning 6 cm clinker 3 cm levelling course

12 cm bearing course

19 cm subbase

A 6 cm clinker for a sqaure that rarely is exposed to trucks or other heavy traffic load (traffic class T1) should have the specified dimensions. Converted, crushed materials can be used as an alternative to virgin materials for the levelling course. The subbase layer is increased from 15 cm to 19 cm to reach the dimensions for construction on a foundation with frost risk10.

Dimensionering En 8 cm klinke som anlægges på en mindre plads, der sjældent er udsat for større køretøjer som lastbilstrafik (trafikklasse T1) vil have de angivede dimensioneringer. I bærelaget kan der bruges genbrugsstabil som alternativ til jomfruelige materialer til stabilgrus. Bundsikringslaget øges fra 15 cm til 19 cm for at nå dimensionerne for anlæggelse på forstivlsom bund10.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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At Dantes Plads, in Copenhagen, there are plans to reuse the existing granite tiles as part of the future renewal, as it was calculated that it would make more sense economically to collect and store them rather than buying new (photo 1). In a private courtyard in Roskilde it was chosen to use reused clinkers from Holland for an entire project due to their aesthetic value (photo 2+3).

In Odense Municipality there has always been a tradition of reusing clinkers.

When clinkers are collected from a project, the municipality store them for later use. With the implementing of the light rail through the city, the municipality have chosen to use a mix of new and reused clinkers (photo 3+4+5)

Photo 1: Dantes Plads. LYTT

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 2: Reused clinker. Klinker Outdoor

Photo 3: Reused clinker. Klinker Outdoor

Photo 4: Reused and new clinkers . Odense Municipality

33 Photo 6: Reused and new clinkers . Odense Municipality

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

Photo 5: Reused and new clinkers . Odense Municipality

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Concrete

Beton

Concrete is a composed stone made of aggregates from sand and stone materials which is glued together by cementpaste of water, lime and sand. Due to the high availability and low price of aggregates worldwide, concrete is one of the most used materials in the construction industry. The Danish concrete industry alone produces more than 1.6 million m3 of concrete for paving stones and ready-mixed concrete per year. It is a strong, inexpensive and durable material that is easy to work with and has a wide range of functions in construction with great variation in shape and sizes. Concrete is rarely reused and recycled.

This is partly due to the way it is constructed, which makes it difficult to disassemble, as well as the lack of financial incentive as concrete is already a cheap product as new. On the other hand, concrete is largely converted into aggregates to e.g. base layer aggregates and aggregates in new concrete, as it is cheaper than raw materials. However, concrete has a great environmental impact due to its cement content, which is responsible for a lot of CO2-emission. Therefore, alternatives are being researched to achieve a more sustainable production.

Beton er en sten sammensat af tilslag fra sand- og stenmaterialer som er sammensat af cementpasta af vand, kalk og sand. Grundet den høje tilgængelighed og lave pris på tilslagsmaterialerne verden over, er beton et af de mest brugte materialer i bygge- og anlægsbranchen. Alene den danske betonindustri producerer over 1,6 million m3 beton til belægningssten og fabriksbeton om året. Beton er et stærkt, billigt og holdbart materiale, der er let at arbejde med og har en bred vifte af funktioner inden for konstruktion med stor variation i form og størrelser. Beton bliver sjældent genbrugt og genanvendt. Det skyldes bl.a. måden det anlægges på, som gør det svært at skille ad, samt manglende økonomisk incitament da beton i forvejen er et billigt produkt som nyt. Til gengæld bliver beton i høj grad genudnyttet i form af tilslagsmateriale i bl.a. genbrugsstabil og nyt beton, da det er billigere end råmaterialer. Dog har beton en stor miljøbelastning grundet dets cementindhold, som har en enorm CO2-udledning. Derfor bliver der forsket i alternativer, for at opnå en mere bæredygtig produktion.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Photo 1: Aggregates mixed at concrete factory.

Aggregates of raw materials are mixed in the factory with water and cement (photo 1). The concrete can then be tapped from the factory into mixing trucks (photo 2) to be used as ready-mix concrete at the project site (photo 3). In the project, Fremtidens GĂĽrdhave, they have used 100% converted concrete as aggregates with new cement (photo 4).

36 common The Circular Properties of Materials in Landscape Architecture 2020-2021 A very concrete element in Copenhagen is the sidewalk tile (photo 5).

Photo 2: Concrete factory.

Photo 3: Ready mix concrete for project.

37 Photo 5: The Copenhagen tile

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

Photo 4: Ready mix concrete for project.

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Raw material extraction

Råstofudvinding

Concrete is a composed stone of a number of natural subcomponents. It usually consists of aggregates of sand and stone materials which are glued together by a paste of water mixed with cement made of chalk and sand16. Concrete is one of the most used building materials worldwide, due to the availability of the aggregates used in making as well as the low price on the materials31. In Denmark, the raw material is extracted from the underground, along the coasts or on the seabed. To extract the materials on land, a bulldozer is used to remove several meters of topsoil, which is being driven to landfill for later use. The sand and stone materials will then be quarried, crushed and loaded into a sorting plant to be sold for construction. The materials found along the coast or on the seabed have been processed by the waves which are making them the best materials for concrete. However, are they less used due to nature conservation considerations. The extraction along the coast and on the seabed takes place with sand suckers, which with a hydraulic pump sucks up the sand into a cargo hold before it is sailed to a distribution site to be finished for use in the construction industry6.

Beton er en sten sammensat af forskellige naturelementer.

Den består som af tilslag af sand- og stenmaterialer, som er sammensat af cementpasta af vand, kalk og sand16. Grundet den høje tilgængelighed og lave pris på tilslagsmaterialerne verden over, er beton et af de mest brugte materialer i byggeog anlægsbranchen31. I Danmark udvindes materialerne fra undergrunden, langs kysterne eller på havbunden og kan variere afhængigt af hvor i landet de er udvundet. For at udvinde materialer på land, benyttes en bulldozer til at fjerne de øverste jordlag bestående af flere meter, som vil blive kørt til deponi for senere eller anden brug. Sandog stentilslagene vil derefter blive udvundet, knust og transporteret til et sorteringsanlæg, hvor det vil blive solgt til anlægs- og byggebranchen. De bedste materialer til tilslag, er de som findes langs kysten og på havbunden, da disse er blevet forarbejdet af bølgerne. Dog bliver kyst- og havbundsmaterialer ikke udvundet i lige så store mængder, som landmaterialerne, da de skal vurderes ift. råstofloven for bevaring af værdifuld natur. Udvindingen foregår ved en sandsuger, der med en hydraulikpumpe suger sand ind på et lastrum. Materialerne sejles herefter til en søplads, hvor de færdigbearbejdes til brug i bygge- og anlægsindustrien6.

The quality of these raw materials is extremely important for both the strength and durability of the finished structures. When the raw material has been extracted it is being safety approved through a CE-certification. It is then divided into four different groups depending on their quality; P (Passive), M (Moderate), A (Aggressive), E (Extra aggressive) with P being the lowest quality and E being the highest. The requirements for the groups are described in building standards and will determine the future use of the concrete6.

Den fremtidige brug og holdbarhed afhænger af blandingen og kvaliteten af råmaterialerne. Efter råmaterialet er blevet udvundet, skal det godkendes gennem en CE-certificering.

Her bliver materialerne inddelt i fire grupper efter en kvalitetssortering; P (Passiv), M (Moderat), A (Aggressiv) og E (Ekstra aggressiv) med P som den dårligste kvalitet og E som den højeste. Kravene for grupperne er beskrevet i byggestandarderne og vil være styrende for betonens fremtidige brug6.

Product manufacturing

Produktfremstilling

Concrete is made by mixing cement, water and aggregates in mixing plants, and is then filled into molds32. The most common aggregates are sand and stone materials, but the aggregates can also consist of converted, crushed clay tiles or concrete. There is an exponential use of converter aggregates due to an increased focus on lack of raw materials. Aggregates make up about 85% of the concrete’s total volume16, which justify the urgency for developing alternative methods in the manufacturing of concrete32. In 2019, it was estimated that the Danish concrete industry annually produces 1 million m3 of concrete for paving stones, and 640,000 m3 of concrete for ready-mixed concrete, which i.a. used for in situ cast concrete and bridges33.

Beton laves ved at blande cement, vand og tilslagsmaterialer i blandingsanlæg som derefter fyldes på støbeform32. De mest brugte tilslagsmaterialer i beton er sand- og stenmaterialer, men kan også bestå af genudnyttede, knuste tagsten eller beton. Dette benyttes i stigende grad grundet et øget fokus på ressourcemangel af råmaterialer. Tilslagsmaterialerne af sand og sten udgør ca. 85% af betonens samlede volumen16, hvilket berettiger det stigende behov for at udvikle alternative metoder til fremstilling af beton32. I 2019 blev det anslået, at den danske betonindustri årligt producerer 1 million m3 beton til belægningssten og 640.000 m3 beton til fabriksbeton som bl.a. bruges ved in-situ støbt beton og broer33.

Product

Produkt

Concrete is, in general, a strong, cheap and durable material that is easy to work with and has a wide range of functions in construction. Many concrete elements are available in standard dimensions, but can be manufactured to almost endless possibilities, e.g. retaining walls, tiles, stairs16. It is, in particular, the composition of the concrete, the quality

Beton er generelt et stærkt, billigt og holdbart materiale, der er let at arbejde med og har en bred vifte af funktioner inden for konstruktion. Mange betonelementer findes i standardmål, men kan fremstilles til næsten uendelige muligheder, f.eks. støttevægge, fliser, trapper16. Det er især betonens sammensætning, kvaliteten af håndværket,

The Circular Properties of Materials in Landscape Architecture 2020-2021

of the craft, the construction of the structure and the surrounding environment in which the concrete is exposed that will determine the concrete’s life expectancy6. An ordinary concrete tile used for sidewalks in Copenhagen is estimated to last between 30-60 years, where factors such as water, frost and salt application gradually will degrade the concrete. Overloading and construction with too small joints can also be a reason why the concrete could break.

It is the cement and aggregates that gives the concrete its characteristic grey colour, but it can come in many variations. Common to the colours is that they change over time due to the bleaching effect of the sun, impurities from the surroundings, but also as a result of limescale deposits.

It is different how quickly the colours change but can be from a few weeks to several years32.

konstruktionen af strukturen og det omgivende miljø, hvori betonen sættes, der bestemmer dets levetid6. En almindelig fortovsflise af beton er normeret til at holde mellem 30-60 år, hvor faktorer som vand, frost og saltning kan være med til at nedbryde betonen. Overbelastning og anlæggelse med for små fuger, kan også være en årsag til betonen vil knække. Det er cementen der giver betonen sin karakteristiske grå farve, men den kan komme i mange variationer. Fælles for farverne er, at de ændrer sig med tiden på grund af solens blegende effekt, urenheder fra omgivelserne, men også som følge af kalkudfældninger.

Hvor hurtigt farverne ændres er vidt forskelligt, det kan være alt fra få uger til flere år32.

Construction

Anlæggelse

Concrete elements are typically cast together with concrete paste. Since concrete can vary a great deal depending on the use, the construction varies as well. Some products are standardized and come as a final product ready to be laid but it is also possible for concrete to be cast directly at the site; cast-in-situ concrete. When the concrete elements are to be laid, it is important to check for limescale deposits, cracks and edge peeling34.

Betonelementer støbes typisk sammen med betonpasta.

Da beton kan variere meget afhængigt af brugen, varierer konstruktionen også. Nogle produkter er standardiserede og kommer som et færdigt produkt, der er klar til at blive lagt, men det er også muligt at støbe beton direkte på stedet; in-situ støbt beton. Når betonelementerne skal anlægges, er det vigtigt at tjekke for kalkudfældning, revner og kantafskalninger34.

Project

Projekt

A well known concrete product is the Copenhagentile that can be found on sidewalks in the Copenhagen area, which has a standard 62,5x80 cm measurement. This tile has a life expectancy of 30-60 years, but many of these sidewalk tiles are more than 60 years old and can usually last for many more years16. The aesthetic life is usually shorter than the functional, and the pavement is therefore often changed even though the technical properties are still in order32.

Et velkendt betonprodukt er Københavnerflisen, der findes på fortove i Københavnsområdet, som er en standard modulflise på 62,5x80 cm. Denne flise har en forventet levetid på 30-60 år, men mange af Københavns Kommunes fortovsfliser er over 60 år gamle og kan generelt set holde i mange år endnu16. Typisk er den æstetiske levetid kortere end den funktionelle. Det medfører, at befæstelsen derfor må lægges om selvom betonens tekniske kvaliteter stadig fungerer32.

Repair

Vedligeholdelse

The surface of the concrete changes over time due to wear and dirt. With severe wear and tear from vehicles, the stones in the concrete will become more visible on the surface. If concrete elements are exposed to a different use than intended or are flawed from production, they can break32. Unfortunately, it is difficult to recreate the original surface in the repair to an extent that it will have the same properties as the original product, as well as to match the original texture and colour since these will change over time. The acidity in rainwater can accelerate the ageing process significantly, and if water cannot run off the surface, it can be absorbed into the concrete where algae and other plants can grow. With concrete being a cheap product, in some cases, it can be a better solution to replace the concrete rather than repairing it, since this might compromise the aesthetic and functional value35.

Betonens udseende ændres med tiden på grund af slid, tilsmudsning med videre. Ved hård slidpåvirkning fra køretøjer vil stenene blive mere synlige i overfladen. Hvis betonelementer udsættes for en anden anvendelse end beregnet eller mangler ved produktionen, kan det gå i stykker32. Desværre er det vanskeligt at genskabe den oprindelige overflade i reparationen i et sådant omfang, at den har de samme egenskaber som det originale produkt, såvel som at matche den originale struktur og farve, da disse vil ændre sig over tid. Syre i regnvand kan fremskynde ældningsprocessen markant. Hvis vand ikke kan løbe af overfladen, kan det absorberes i betonen, hvor alger og andre planter så kan vokse. Da beton er et billigt produkt, kan det i nogle tilfælde være en bedre løsning at erstatte betonen i stedet for at reparere den, da en reparation kan kompromittere den æstetiske og funktionelle værdi35.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Reuse

Genbrug

Reusing concrete in new projects is not a widespread method in Denmark. This is partly due to how concrete elements are assembled. Concrete elements are typically cast together with concrete paste, making it impossible to disassemble without damaging it, and the load-bearing capacity of the elements will not necessarily be known afterwards. Another reason for not reusing concrete is their relatively short life expectancy compared to many types of natural pavement tiles, where it in some cases can be a cheaper solution to buy new concrete bricks rather than reused which needs to be exchanged quicker36.

At genbruge beton i nye projekter er ikke en udbredt metode i Danmark. Dette skyldes dels den måde, hvorpå betonelementer samles. Betonelementer støbes typisk sammen med betonpasta, hvilket gør det umuligt at adskille uden at beskadige det, og elementernes bæreevne vil ikke nødvendigvis være kendt bagefter. En anden grund til ikke at genbruge beton er deres relativt korte forventede levetid sammenlignet med mange naturlige belægningssten, hvor det i nogle tilfælde kan være en billigere løsning at købe nye betonsten i stedet for genbrugte, som hurtigere skal udskiftes36.

Recycle

Genanvende

Like reusing, recycling concrete in new pavement projects is not a common method in Denmark. It involves several challenges in decomposing the concrete into usable sizes and there is a lack of financial initiative recycling instead of buying new, with concrete already being a cheap product37.

Genanvendelse af beton i nye anlægsprojekter, er ikke en benyttet metode i Danmark. Det skyldes, at der ligger en række udfordringer i at nedbryde betonen til anvendelige størrelse og manglende økonomisk incitament til at genanvende fremfor at købe nyt, da beton i forvejen er et billigt produkt37.

Conversion

Genudnytte

Converting concrete into smaller aggregates to use in unbound base layers is the most common way of using concrete waste. However, is it important to distinguish between concrete that has not been used in constructions and concrete that has been used in constructions. Concrete that has not been used in construction will typically be surplus concrete from e.g. in-situ cast concrete and can be used as aggregates in the same environmental class as it was originally intended. Concrete that has previously been used in constructions can be used as aggregates for converted aggregates equal to raw materials, as long as it can be documented for the quality and meet a number of purity requirements, which can be problematic to obtain38.

Converted aggregates are made from concrete waste that has been collected from construction sites, which then is transported to a recycling company, where foreign objects are being removed and the concrete is crushed into 0-32 mm grits. Converted concrete aggregates are often cheaper than raw materials, and the demand is therefore increasing. This is happening as the raw material resources around the big cities are beginning to be scarce, which motives to develop new production methods and norms for construction37.

Den mest almindelige måde at bruge beton på igen, er ved genudnyttelse som tilslag i ubundet bærelag. Man skelner her mellem beton der ikke har været brugt i konstruktioner, og beton, der har været brugt i konstruktioner. Beton der ikke har været brugt i beton vil typisk være overskudsbeton fra f.eks. anlæggelse af in-situ støbt beton og må bruges som tilslag i samme miljøklasse som det oprindeligt var tiltænkt. Beton der tidligere har været brugt i konstruktioner kan bruges som tilslag til genbrugsstabil på lige fod med som råmaterialer, så længe der kan dokumenteres for kvaliteten, samt opfylde en række renhedskrav, hvilket dog kan være problematisk at skaffe38. Genbrugsstabil dannes ved at indsamle betonaffald fra byggepladser hvor det transporteres til et genbrugsfirma som frasorterer fremmedlegemer og knuser det til tilslag i 0-32 mm kornstørrelser. Genbrugsstabil er ofte billigere end råmaterialer, og efterspørgslen er derfor stigende. Dette sker i takt med, at råmaterialeressourcerne omkring de store byer begynder at være knappe, hvilket motiverer flere til at udvikle nye fremstillingsmetoder og normer i anlægsbranchen37.

Depositing

Deponering

Concrete accounts for approximately 25% of all construction and demolition waste in Denmark. In 2018 it was estimated that up to 97% of the registered concrete waste was recovered and converted into aggregates rather than ending up as landfill38.

Beton dækker over ca. 25% af alt bygge- og nedrivningsaffald i Danmark. I 2018 blev det anslået, at op til 97% af det registrerede betonaffald blev omdannet og genudnyttet til tilslag fremfor at ende til deponi38.

Energy consumption

Energiudledning

Life cycle analyzes show that the transport of concrete has a marginal significance in the total CO2-emission in concrete manufacturing. Instead, the cement industry

Livscyklusanalyser viser, at transport af beton har marginal betydning i den samlede CO2-udledning i beton produktionen. Derimod er særligt cementindustrien

The Circular Properties of Materials in Landscape Architecture 2020-2021

accounts for 80% of the total energy discharge in concrete manufacturing. This makes the cement and concrete industry accountable for approximately 8% of total CO2emission worldwide17. This is despite the fact that cement only makes up approximately 12% of the finished concrete block32. Dansk Byggeri estimates that the production for concrete pavement emits 260,000 tonnes of CO2/year, and that ready-mixed concrete for e.g. in situ cast concrete and bridges emit 360,000 tons of CO2/year. With the Danish government’s target of 70% less CO2-emissions from the cement and concrete industry from 1990-2030, research is being carried out with more sustainable production.

This will be achieved through less emissions during manufacturing, life cycle mapping, material alternatives research and certification schemes - among other initiatives33. An interesting example of this is a study from 2019, where new material compositions in concrete were tested. By replacing some of the limestone with calcined (burnt) clay, it is possible to lower the energy consumption in cement production, as clay uses less energy during firing than limestone. Overall, this will lower the CO2-emissions of the cement production39.

den store synder, som står for 80% af den samlede energiudladning. Samlet står de to for ca. ca. 8% af den samlede CO2-udledning på verdensplan17. Det er på trods af, at cement kun udgør ca. 12% af den færdige betonsten32.

Dansk Byggeri estimerer, at belægningssten af beton udleder 260.000 ton CO2/året, og at fabriksbeton til bl.a. in situ støbt beton og broer udleder 360.000 ton CO2/året. Med regeringens målsætning om 70% mindre CO2 udledning cement- og betonindustrien fra år 1990-2030, bliver der forsket meget i hvordan der opnås en mere bæredygtig produktion. Det vil bl.a. nås ved mindre udledning under produktion, kortlæggelse af livstidscyklusen, forskning i materialealternativer og certificeringsordninger33. Et spændende eksempel herpå er et studie fra 2019, hvor der bliver testet nye materialesammensætninger i beton. Ved at erstatte noget af kalken med kalcineret (brændt) ler er det muligt at sænke energiforbruget i cementproduktionen, da leret benytter mindre energi ved brændingen end kalk. Dette vil samlet sænke cementproduktionens CO2udledning39.

Price range: 187-232 kr./m2 Dimensioning

6 cm concrete tile 3 cm levelling course

12 cm bearing course

A 6 cm concrete tile for a sqaure that rarely is exposed to trucks or other heavy traffic load (traffic class T1) should have the specified dimensions. Crushed, converted concrete can be used as an alternative to virgin materials for the levelling course. The subbase layer is increased from 15 cm to 19 cm to reach the dimensions for construction on a foundtation with frost risk . For heavier traffic class, it is recommended that joints, leveling courses and base layers are made of bonded materials in the form of concrete or asphalt10. However, this will make it difficult to reuse, recycle and converte the concrete in other projects, since it then have to undergo cleaning process through machines and chemicals.

Dimensionering

10 cm subbase

En 6 cm betonflise som anlægges på en mindre plads, der sjældent er udsat for større køretøjer som lastbilstrafik (trafikklasse T1) vil have de angivede dimensioneringer.

I bærelaget kan der bruges nedknust, genudnyttet beton, som alternativ til jomfruelige materialer til stabilgrus.

Bundsikringslaget øges fra 15 cm til 19 cm for at nå dimensionerne for anlæggelse på forstivlsom bund. For tungere trafikklasse anbefales det, at fuger, afretningslag og bærelag udføres i bundne materialer i form af beton eller asfalt10. Dette vil dog gøre det svært genbruge, genanvende og genudnytte betonen i andre sammenhænge, da man i så fald skal benytte maskiner og kemikalier for at rense stenen.

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Photo 1: Converted aggregates for concrete.

By converting concrete elements into 0-32 mm grits they can be used as aggregates in new concrete (photo 1).

In Bispehaven, Ă…rhus the landscape architectural studio, byMunch, have experimented with recycling former concrete elements, such as walls, into pavement elements (photo 2).

The result of concrete edges andinretaining of converted 42finalThe Circular Properties of Materials Landscapewalls Architecture 2020-2021concrete aggregates (photo 3+4).

Photo 2: Recycled concrete.

Photo 3: Retaining wall made from converted concrete.

43 Photo 4: Edge made from converted concrete.

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The Circular Properties of Materials in Landscape Architecture 2020-2021

Sandstone

Sandsten

Sandstone is a result of weathered rocks and sand sediments that were compacted nearly 1 billion years ago, creating a stratification that is particularly characteristic of these types of rocks. The various quarries and stratification create a large variety of colours for example yellow, green, blue and red. Each cleaving creates different structures on the surface of the sandstone and they, therefore, vary greatly. The stones can be made into paving stones in different sizes, e.g. as cobblestones or as larger tiles. However, the country of origin has a great influence on their technical qualities, and especially the Indian sandstone shows high tensile bending strength and therefore has good potential for use.

In Denmark, there is not much tradition of using sandstone in larger construction projects, and are mostly found in smaller, private projects. They have a very long lifespan, and if laid in sand, they can be easily picked up and reused in new projects. It is rarely seen that sandstone is recycled or reused.

Sandsten er et resultat af forvitrede klipper og sandsedimenter, der blev komprimeret for næsten 1 milliard år siden, hvilket skabte den lagdeling, der er særligt karakteristisk for disse typer sten.

De forskellige stenbrud og lagdelingen skaber et stort udvalg af farver for eksempel gul, grøn, blå og rød. Hver kløvning skaber forskellige strukturer på overfladen af ​​sandstenen, og de varierer derfor meget. Stenene kan laves til belægningssten i forskellige størrelser, f.eks. som brosten eller som større fliser. Dog har oprindelseslandet en stor indflydelse på deres tekniske kvaliteter, hvor særligt den indiske sandsten viser høje bøjetrækstyrke og har derfor gode muligheder for brug. I Danmark er der ikke stor tradition for at bruge sandsten i større anlægningsprojekter, og man finder dem snarere i mindre, private projekter.

De har en meget lang levetid, og hvis de anlægges i sand, kan de nemt tages op og genbruges i nye projekter. Det ses sjældent at sandsten bliver genanvendt eller genudnyttet.

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Sandstones are extracted from quarries like the one in India (photo 1). The 1 billion years of compacting the sediments have created the unique stratification (photo 2) and every cleaving creates different structures on the surface of the sandstone (photo 3). After extraction the sandstone is processed in the required sizes at the quarry and packed onto pallets for transportation (photo 4). The processed sandstone comes in almost endless variations of shapes, sizes and colours (photo 6+7) and the colour will vary when wet and dry (photo 5).

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Photo 1: Quarry in India. Sandstone Natursten

The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 2: Rough block of sandstone.

Photo 3: Rough block of sandstone.

Photo 4: Sandstone on pallets. Sandstone Natursten

Photo 5: Wet and dry sandstone.

Photo 6: Various sandstone.

47 Photo 7: Various sandstone.

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Raw material extraction

Råstofudvinding

Sandstone is a result of weathered rocks and sand sediments that were compacted almost 1 billion years ago creating a stratification, that is especially characteristic for these types of stones. The different quarries and the stratification creates a large variety of colours for instance yellow, green, blue and red. Every cleaving creates different structures on the surface of the sandstone, and they, therefore, vary a lot. Sandstone quarries are mostly found in India, but some sandstones used for pavings in Denmark also originate from Germany and England11. However, sandstones can also be found on Bornholm, in the subsoil, and is called Nexø sandstone. This sandstone is not very widespread but is still seen in smaller public areas and private gardens and terraces40. A distributor of sandstone in Denmark is Sandstone Natursten. They explain that some of the English and German sandstones almost are too porous to be used as pavings but are more suitable for instance on churches to create more details. Furthermore, they explain that the sandstones found in India have been heavily compressed which makes the stone resistant to the Danish climate and for outdoor pavings. This is also why they mostly sell sandstones imported from India to Danish landscape projects11. Sandstones are extracted by cleaving, drilling and blasting out large rough blocks of stone. It can also be done by cutting and slitting. This depends on the structure of the sandstone. If it is softer, it can more easily be done by cutting, whereas harder structures, such as the Indian sandstone, are more likely drilled or blasted41.

Sandsten er et resultat af forvitrede klipper og sandsedimenter, der blev komprimeret for næsten 1 milliard år siden, hvilket skabte en lagdeling, der er særligt karakteristisk for disse typer sten. De forskellige stenbrud og lagdelingen skaber et stort udvalg af farver for eksempel gul, grøn, blå og rød. Hver kløvning skaber forskellige strukturer på overfladen af sandstenen, ​​ og de varierer derfor meget. Sandstensbrud findes for det meste i Indien, men nogle sandsten, der anvendes til belægning i Danmark, stammer også fra Tyskland og England11. Sandsten findes imidlertid også i Bornholms undergrund og kaldes Nexø sandsten. Denne sandsten er ikke særlig udbredt, men ses dog i mindre offentlige anlæg, samt i private haver og terrasser40. Sandstone Natursten er leverandør af sandsten i Danmark. De forklarer, at nogle af de engelske og tyske sandsten næsten er for porøse til at blive brugt som belægning, men er mere velegnede f.eks. til kirker for at skabe flere detaljer. Desuden forklarer de, at de sandsten, der findes i Indien, er blevet kraftigt komprimeret, hvilket gør stenen modstandsdygtig over for det danske klima og til udendørs belægninger. Dette er også grunden til, at de for det meste sælger sandsten importeret fra Indien til danske landskabsprojekter11. Sandsten udvindes ved kløvning, boring og sprængning af store grove stenblokke.

Det kan også gøres ved at save og skære. Dette afhænger af sandstenens struktur. Hvis det er blødere strukturer, kan det lettere gøres ved at skære, mens hårdere strukturer, såsom den indiske sandsten, mere sandsynligt bores eller sprænges41.

Product manufacturing

Produktfremstilling

As for the Indian sandstone, the sandstone materials get manufactured at the quarries. They are cleaved into the desired sizes and cut to achieve the desired thickness as well. This is often done by manual power, which limits the CO2 emission. Though is it possible to saw or polish the surface afterwards to achieve a more even surface than if cleaved, but the cleaved surface is mostly used in Denmark due to its skidproof qualities and for aesthetic reasons. A result of the heavily compressed stratification of the Indian sandstones is a high tensile bending strength. This allows for a thinner product, that still has the strength to handle the heaviest traffic load from the danish building standard11.

Hvad angår den indiske sandsten, bliver sandstenmaterialerne fremstillet ved stenbruddene. De kløves i de ønskede størrelser og skæres til for at opnå den ønskede tykkelse. Dette gøres ofte ved håndkraft, hvilket begrænser CO2-udledningen. Det er muligt at save eller polere overfladen af sandstenen for at opnå en mere jævn overflade end hvis den er kløvet, men den kløvede overflade bruges mest i Danmark på grund af dens skridsikre egenskaber og af æstetiske grunde. Et resultat af den stærkt komprimerede lagdeling er en høj bøje -trækstyrke. Dette giver mulighed for at producere et tyndere produkt, der stadig har styrken til at håndtere den tungeste trafikbelastning fra Normer og Vejledning for Anlægsgartnerarbejde11.

Product

Produkt

Sandstones were created long ago, and this together with how the sediments were deposited make the lifespan of these sandstones very long. It might even be infinite.

Sandstone Natursten explains that for the Indian sandstone they expect a very long lifespan. As for other sandstones, the lifespan and quality can vary11. In Denmark, sandstones have especially been used on façades and monuments42, and not as much for pavings, which make the lifespan for sandstone pavings difficult to account for.

Sandsten blev skabt for længe siden, hvilket sammenlagt med hvordan sedimenterne blev deponeret gør, at levetiden for disse sandsten er meget lang. Den kan endda være uendeligt. Sandsten Natursten forklarer, at den indiske sandsten har en meget lang forventet levetid. For andre sandsten kan levetiden og kvaliteten variere11. I Danmark er der især anvendt sandsten på facader og monumenter42 og ikke så meget til belægninger, hvilket gør det svært at redegøre for levetiden for sandstenbelægninger.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Sandstones can be made into paving stones in various sizes e.g. as cobblestones or as larger tiles. Fractions of sandstones can also be used to make stone walls. The different quarries provide a large variation of colours and the stratification gives every stone an individual expression. The colours are often in warm shades, and sometimes the colours can be quite colour saturated and have a completely different expression when exposed to water. All sandstones from Sandstone Natursten have been tested to meet the danish and European standards and are furthermore CE-certified. This means for instance that they are frost and salt resistant as well as skid-proof. But since sandstones can be quite diverse and have various qualities, it can be difficult and costly to control and certify sandstones in general11.

Sandsten kan laves til belægningssten i forskellige størrelser, f.eks. som brosten eller som større fliser.

Brudstykker af sandsten kan også bruges til at lave stenvægge. De forskellige stenbrud giver en stor variation af farver, og lagdelingen giver hver sten et individuelt udtryk. Farverne er ofte i varme nuancer, og nogle gange kan farverne være meget farvemættede og få et helt andet udtryk, når de eksponeres for vand. Alle sandsten fra Sandstone Natursten er testet til at opfylde de danske og europæiske standarder og er desuden CE-certificeret. Dette betyder f.eks., at de er frost- og saltbestandige såvel som skridsikre. Men da sandsten kan være ret forskelligartede og have forskellig kvalitet, kan det være svært og dyrt at kontrollere og certificere sandsten generelt11.

Construction

Anlæggelse

Sandstone products are mostly placed in sand, but it happens that they are cast in concrete. If so, the product becomes more difficult to recycle. Due to the Indian sandstone’s high tensile bending strength, the product can be made thin, which decreases the heavy load when constructing a project11.

Sandstenprodukter sættes for det meste i sand, men det sker, at de er støbt i beton. I så fald bliver produktet sværere at genbruge. På grund af den indiske sandstens høje bøjetrækstyrke kan produktet gøres tyndt, hvilket reducerer den tunge belastning, når der anlægges et projekt11.

Project

Projekt

In Denmark, it is difficult to find ancient sandstones from former landscape projects. Some places one can find smaller areas of ancient sandstone for instance at G.N. Brandt’s Rosenhaven, in Hellerup Strandpark from 191843.

Today new sandstones can be found in smaller public projects on roads and squares but are not yet a very common product in Denmark. Sandstone products are therefore mostly found in private projects such as terraces and driveways11. However, historically the first gutters in Denmark were made of sandstone from a Swedish mountain called Kinnekulle, which is why gutters still today, sometimes are called by this name. Today the gutters are also made of concrete, and some are underground44.

I Danmark er det vanskeligt at finde gamle sandsten fra tidligere landskabsprojekter. Nogle steder kan man finde mindre områder af gamle sandsten for eksempel ved G.N. Brandt’s Rosenhaven, i Hellerup Strandpark fra 191843. I dag findes nye sandsten i mindre offentlige projekter på veje og pladser, men er endnu ikke et udbredt produkt i Danmark. Sandstensprodukter findes derfor mest i private projekter som terrasser og indkørsler11. Historisk set var de første vandrender i Danmark imidlertid lavet af sandsten fra et svensk bjerg ved navn Kinnekulle, og derfor kaldes vandrender stadig i dag undertiden under dette navn. I dag er vandrender også lavet af beton, og nogle er nedgravet44.

Repair

Vedligeholdelse

Sandstones contain micropores, which in weather conditions will result in algae turning the surface of the stone green. This acquired patina will increase if the sandstones are exposed to moisture and shadow45. It is possible to maintain sandstones, due to its high tolerance to a high-pressure washer, algae cleanser and various cleaning materials. Sandstones require to be cleansed once or twice a year to uphold its original aesthetic, depending on the environment in which they are placed.

This is valid to the Indian sandstone since other variations of sandstones from other countries can be less robust and thereby not as easy to maintain and repair11. Should a stone break, it can easily be replaced. This was seen in G.N. Brandt’s Rosenhave when it was renovated for its 100th anniversary. Only a few stones had broken over 100 years, and these could easily be replaced with new ones, that were carefully selected to look like the originals43.

Sandsten indeholder mikroporer, som ved påvirkning af vind og vejr vil resultere i, at alger gør stenens overflade grøn. Denne patina vil stige, hvis sandstenene udsættes for fugt og skygge45. Det er muligt at vedligeholde sandsten på grund af dens høje tolerance over for en højtryksspuler, algerens og forskellige rengøringsmidler. For at beholde dens originale æstetiske udtryk, skal sandstenen rengøres en til to gang om året, afhængigt af det miljø, de placeres i.

Dette gælder for den indiske sandsten, da andre variationer af sandsten fra andre lande kan være mindre robuste og dermed ikke så lette at vedligeholde og reparere11. Skulle det ske, at en sten gik i stykker, kan man nemt udskifte dem.

Dette så man f.eks. i G.N. Brandt’s Rosenhave da den blev renoveret ved sit 100 års jubilæum. Her var kun få sten gået i stykker over 100 år, og disse kunne nemt udskiftes med nye som nøje var blevet udvalgt for at ligne de originale43.

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Reuse

Genbrug

Due to sandstone’s long lifespan, it is easy to reuse in other projects but it is a matter of how the stone is placed.

If placed in a loose joint, it is very easy to reuse. If cast in concrete the sandstone becomes more difficult to replace in another project, and it would take machinery and chemistry to reuse it. There are no immediate examples of projects with reused sandstone since the material is still quite new in a danish context and not very often seen in danish landscape architecture11.

På grund af sandstens lange levetid er det let at genbruge det i andre projekter, men det er et spørgsmål om, hvordan de sættes. Hvis de sættes i en løs fuge, er de meget lette at genbruge. Hvis sandsten er støbt i beton, bliver de sværere at genbruge i et andet projekt, og det vil kræve maskiner og kemi at rense dem. Der er umiddelbart ingen eksempler på projekter med genbrugt sandsten, da materialet stadig er ret nyt i dansk sammenhæng og ikke særlig ofte ses i dansk landskabsarkitektur11.

Recycle

Genanvende

It is possible to produce a new product out of pre-used or damaged sandstones, but it is a time and cost consuming process. It is mostly seen that fractions of a sandstone, will be used in a stonewall, or a larger piece like a broken flagstone, in paving11.

Det er muligt at fremstille et nyt produkt ud af forbrugte eller beskadigede sandsten, men dette er en tid- og omkostningskrævende proces. Det er typisk fraktioner af en sandsten, der vil blive brugt i en stenmur eller et større stykke som en brudt flise, til brolægning11.

Conversion

Genudnytte

When producing sandstone products, some waste can occur. This can be used as shards, which can subsequently be used in road filling. The stratification of the sandstone causes the fragments of sandstone to be sharp, and therefore not suitable as pavement. However, due to the robustness of sandstone, fractions will rarely occur11.

Hvis der opstår stenaffald i produktionen af sandsten kan disse bruges som skærver, der efterfølgende kan benyttes til vejfyld. Sandstens lagdeling og derved struktur gør, at småstykker fra sandsten kan være skarpe, og derfor ikke anvendelige til belægninger. Men grundet sandstens robusthed, vil der sjældent opstå småstykker11.

Depositing

Deponiering

Only a small part of sandstones will end up as waste deposit, due to sandstones long lifespan. The depositing of sandstone occurs if the process of clearing does not take the recyclability of the material into account11.

Kun en lille del af sandsten vil ende i deponi. Dette sker, hvis der i rydningsprocessen ikke tages højde for materialets genbrugelighed11.

Energy consumption

Energi udledning

When the sandstones have been extracted from the quarries in India, they are transported by primarily freight trains to a port. Large containerships transport the sandstones to Germany, where they are then transhipped to smaller container ships that can enter the port of Copenhagen. They are then transported by trucks to the project where they are used or storagearea. As large quantities of sandstone can be loaded on container ships from India, the energy emissions will be smaller than if the same amount of sandstone were to be transported by truck from the Nordic countries or Europe11. Sandstone Natursten has had Zoffmannholm landscape architects compare the CO2-emission from production and transportation of an Indian sandstone with a standard concrete tile. Here it turned out that the primary CO2-emission for sandstone is in transport. The study showed that 1 kg sandstone emmit 0.024-0.027 kg CO2 from quarry in India to storage in Denmark, which is five times less than 1 kg concrete tile extracted and produced in Denmark46.

Når sandstenene skal transporteres fra stenbruddene i Indien til Danmark, sker dette primært med godstog ned til havnen. Fra havnen i Indien transporteres de med store containerskibe til Tyskland, hvor de omlastes til mindre containerskibe, der kan komme ind i Københavns havn. Når de herfra skal videre til projektområder eller til opbevares, foregår transporten med lastbil. Da der på containerskibe kan lastes store mængder sandsten fra Indien, vil energiudslippet blive mindre, end hvis den samme mængde sandsten skulle transporteres med lastbil fra Norden eller Europa11. Sandstone Natursten har fået Zoffmannholm landskabsarkitekter til at sammenligne CO2-udledningen fra produktion og transport af en indisk sandsten med en standard betonflise. Her viste det sig, at den primære CO2-udledning for sandsten er i transport.

Undersøgelsen viste, at 1 kg sandsten udleder 0,0240,027 kg CO2 fra udvindingen i stenbrud i Indien til lagring i Danmark, hvilket er fem gange mindre end 1 kg betonfliser udvundet og produceret i Danmark46.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Price range: 319-429 kr./m2 Dimensioning

8 cm sandstone tile 3 cm levelling course

12 cm bearing course

17 cm subbase

A 8 cm sandstone tile for a sqaure that rarely is exposed to trucks or other heavy traffic load (traffic class T1) should have the specified dimensions. Converted, crushed materials can be used as an alternative to virgin materials for the levelling course. The subbase layer is increased from 15 cm to 17 cm to reach the dimensions for construction on a foundtation with frost risk . For heavier traffic class, it is recommended that joints, leveling courses and base layers are made of bonded materials in the form of concrete or asphalt10. However, this will make it difficult to reuse, recycle and converte the sandstone in other projects, since it then have to undergo cleaning process through machines and chemicals.

Dimensionering En 8 cm sandstensflise som anlægges på en mindre plads, der sjældent er udsat for større køretøjer som lastbilstrafik (trafikklasse T1) vil have de angivede dimensioneringer.

I bærelaget kan der bruges genbrugsstabil som alternativ til jomfruelige materialer til stabilgrus. Bundsikringslaget øges fra 15 cm til 17 cm for at nå dimensionerne for anlæggelse på forstivlsom bund. For tungere trafikklasse anbefales det, at fuger, afretningslag og bærelag udføres i bundne materialer i form af beton eller asfalt10. Dette vil dog gøre det svært genbruge, genanvende og genudnytte sandstenen i andre sammenhænge, da man i så fald skal benytte maskiner og kemikalier for at rense flisen.

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Sandstones were used for pavement in a courtyard project in 2013 (photo 1). With minimum maintenance it allows algaes and other plants to grow on the tiles, making them somewhat slippery. It also has an impact on the colour scheme on the pavement (photo 2).

In 1918 sandstones were used in G.N. Brandt’s Rosenhave. In the renewal in 2018 only few tiles were broken where it was managed to replace the broken tiles with new ones in a similar colour scheme (photo 4+5).

At Absalonsgade in Copenhagen it is still possible to find the original gutters, the kinnekulle, made from sandstone from the swedish mountain Kinnekulle (photo 6).

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Photo 1: Courtyard project 2013. Sandstone Natursten

The Circular Properties of Materials in Landscape Architecture 2020-2021

Photo 2: Courtyard project 2021.

Photo 3: Courtyard project 2021.

Photo 4: G.N. Brandt Rosenhave. Schul Landskabsarkitekter

53 Photo 6: Kinnekulle

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

Photo 5: Kinnekulle

Methods After participating in workshops and lectures on circular economy in landscape architecture, which presented a large number of issues within the subject, our interest in particularly the circularity of materials within landscape architecture began. We became more knowledgeable about the great responsibility the construction industry has in the CO2-emission. Studies were presented on how we can reduce the use of our raw materials as well as the economical, functional and aesthetic issues in reusing and recycling construction materials. This created a breeding ground for this project.

Based on results and studies from especially Danish Landscape Architects’ ‘Eksempelsamling for Cirkulær Økonomi’2, the studies made by the Ellen McArthur Foundation2 and Aarhus Municipality’s catalogue on Circular Economy in the construction industry47, we became further updated on the subject. However, a large part of the research was more often related to the building industry than the construction industry.

By further investigation and by being critical of the studies and results, we compared the issues that exist in both the building and construction industry. Furthermore, we reviewed and questioned the uncertainties that occurred in the industry. It became clear to us that we needed to unfold the topic further. By including and describing the processes before, during and after construction, we were able to form a better overall picture of the circular rotation and lifespan of pavement materials.

We then examined a number of materials and chose to continue the investigation of the following; sandstone, concrete, granite and clinkers. These were selected according to what we found were most used in Danish landscape architecture, or which had the potential to be used more - all with very different qualities. Then started the process of contacting distributors, manufacturers and landscape architects who were to help us illuminate the various materials. We prepared a questionnaire that could help us to shed light on the qualities and challenges of the materials, as well as provide an understanding of the general perspectives in the use of the material. Since the majority of research, diagrams and reports often dealt with the construction industry, we designed a diagram adapted to the construction industry, to better communicate the potentials and barriers.

The diagram unfolded the principles and focus points within the circular economy that we found relevant in a landscape architectural context. This involved the extraction of raw materials, the construction of a project and the recyclable possibilities of the material among other aspects. It helped us to create an understanding of how the different materials were part of a circular rotation as well as to portray their various potentials.

Then followed a line of visits to the distributors. We visited the granite distributors Zurface and Bent Vangsø Granit at Prøvestenen in Copenhagen, where we were able to get an insight into how they receive, divide and store their products. At Prøvestenen we passed several concrete production companies, but which unfortunately could not stand for an interview. We were able to schedule an excursion to Sorø to visit Sandstone Natursten, who has the largest selection of sandstones in Northern Europe. They kindly offered a tour of their exhibition garden and provided us with a great selection of material samples to take home for our exhibition. Due to corona restrictions and general logistics, we were never able to visit the clinker manufacturer, Klinker Outdoor, and instead, we did the interview over the phone.

Throughout the process we have been in contact with a range of landscape architectural studios to learn more of their considerations in selecting materials. We have spoken with landscape architect Jacob Sandell from Schønherr regarding the concrete elements in front of Nordvest Bibliotek og Kulturhus, as well as landscape architect Anita Munch from byMunch, who experimented with recycled concrete elements in their project. We visited the project, Fremtidens Gårdhave ved Straussvej, where they were in the process of casting concrete elements of converted concrete to get an understanding of the possibilities with this material. Landscape architect Torben Møbjerg from LYTT was able

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The Circular Properties of Materials in Landscape Architecture 2020-2021

to inform us of their work in reusing and recycling granite at Christiansborg Slotsplads, where landscape architect Tine Langsted Krogstrup from SLA contributed photos and knowledge about recycling granite in the project at Andreas Steenbergs Plads. Landscape architect Anne Ramsborg from Odense Municipality was able to shed light on their considerations for their long tradition of using new and reused clinkers. Unfortunately, we could not get in touch with anyone who had used reused sandstone in their projects, but we managed to find historical sandstone drains and to visit a courtyard in Copenhagen where sandstone was used as a pavement in a project from 2013. We used this to shed light on issues and considerations with maintenance in particular. Finally, we had a meeting with landscape architect Martin Hedevang Andersen who is the coordinator of Danish Landscape Architect’s committee for circular economy who contributed with interesting perspectives for our future work.

The great work in interpreting and understanding the various information we had obtained through interviews, literature and project visits was ongoing throughout the process, as we continued to gain more knowledge. We seeked to communicate this knowledge in the form of posters for exhibition as well as an exhibition catalogue. During January, we had to realize that the exhibition, unfortunately, would not become relevant due to the prolonged restrictions of COVID-19 and our exhibition catalogue was therefore changed to a report.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Reflections

56

By examining and explaining the four materials and their circular properties, a greater overview of their different potentials within circularity has been formed. However, in this process, barriers associated with the materials being in a circular cycle are also highlighted. Some of these apply to the individual materials, while others are some more general challenges. Both are supported by conversations with distributors of the products, landscape architects who have worked with the various materials as well as articles and reports commenting on the different aspects of the circular economy.

Ved at have undersøgt og redegjort for de fire materialer og deres cirkulære egenskaber, er der dannet et større overblik over deres forskellige potentialer inden for cirkularitet. Men i denne proces, er der også belyst barrierer forbundet med at materialerne er i et cirkulært kredsløb. Nogle af disse er gældende for de enkelte materialer, hvor andre er nogle mere generelle udfordringer. De understøttes af samtaler med forhandlere af produkterne og landskabsarkitekter, som har arbejdet med de forskellige materialer, samt artikler og rapporter, der kommenterer de forskellige aspekter af den cirkulære økonomi.

Clearing work

Rydningsarbejde

When a project is to be cleared, there first has to be an estimate of whether the products in the project are able to be included in a circular rotation. This can both be time-consuming and challenging since it involves a lot of logistics and finances. If the product is to be included in the circular rotation, there is a lot of manual work in sorting and classification of the products. Furthermore, the sorting can be space consuming, and often be a nuisance to the neighbours. Coordination and logistics typically cost more than if the products just need to be driven away for landfill.

Therefore, the incentive to get circular products may not excist.

Når et projekt skal ryddes er der først et vurderingsarbejde i at beslutte, om produkterne på projektområdet skal optages i et cirkulært kredsløb. Dette kan tage tid og være udfordrende i og med det indbefatter en masse logistik og økonomi. Hvis produktet skal indgå i det cirkulære kredsløb er der et større sorteringsarbejde, som ofte gøres manuelt, hvilket er tidskrævende. Sorteringen kan også være pladskrævende, og generelt være til gene for naboerne.

Koordinering og logistik koster typisk mere, end hvis produkterne blot skal køres væk. Derfor kan incitamentet for at få cirkulære produkter være lille.

Storage

Opbevaring

If it is assessed that the materials in a project should be recycled, they typically have to be sorted and stored. Not all municipalities offer a storage solution, and this can often end up being an expensive solution. Especially if the project drags on and the materials have to be stored longer than expected. Furthermore, several municipalities only offer to store materials for the municipality’s own projects, which makes it problematic for private projects to store materials for recycling. In order for materials to be used in a new project, it must be more accessible to both sell and procure materials.

Hvis der vurderes at materialerne i et projekt skal genbruges, skal de typisk sorteres og opbevares. Det er ikke alle kommuner som tilbyder en opbevaringsløsning, og dette kan tit ende med at være en dyr løsning - særligt hvis projektet trækker ud og materialerne skal opbevares længere end forventet. Derudover tilbyder flere kommuner kun at opbevare materialer for kommunens egne projekter, hvilket gør det problematisk for private projekter at opbevare materialer til genbrug. For at materialer kan komme i brug i et nyt projekt, skal det være mere tilgængeligt at både afsætte og fremskaffe materialer.

Transport

Transport

From the excavation of raw materials to the finished product, transport is included. When the products are subsequently to be included in a circular circuit, there is again a lot of transport involved, such as transport for storage, for cleaning and out for a new project. Many participants need to be involved and coordinated, and the CO2 emissions associated with transport cannot be ignored.

Fra udgravningen af råmaterialer til det færdige produkt indgår transport. Når produkterne efterfølgende skal indgå i et cirkulært kredsløb, er der igen en masse transport indblandet, såsom transport til opbevaring, til rensning og ud til et nyt projekt. Mange aktører skal indblandes og koordineres, og CO2-udledningen forbundet med transporten, kan ikke ignoreres.

Cleaning

Rensning

In some cases, used products have to be cleaned in order to be used again due to both aesthetic and technical reasons.

The cleaning has costs associated and sometimes both machines and/or chemicals must be used in the process.

I visse tilfælde skal de brugte produkter renses for at kunne bruges igen, både af æstetiske og tekniske årsager.

Rensningen har omkostninger forbundet og somme tider skal der anvendes både maskiner og/eller kemikalier i processen.

The Circular Properties of Materials in Landscape Architecture 2020-2021

Parties

Aktører

Typically, those who build a new project will not be the same as those who clear the project later. The economics of the two items are separate, and therefore there is not always an economic incentive to choose a product with a longer lifespan or use products from a circular rotation.

In this process, several actors are involved, such as the builder, landscape architects and landscape gardeners, where all of whom must reach an agreement. By using circular products, problems can also arise in who should be responsible for the quality of the product when it can be challenging to trace the material’s original properties.

Typisk vil dem der anlægger et nyt projekt ikke være de samme, som dem der rydder projektet senere hen. Økonomien for de to poster er adskilt, og der er derfor ikke altid et økonomisk incitament i at vælge et produkt med en længere levetid eller bruge produkter fra et cirkulært kredsløb. Desuden er der i denne proces, flere aktører indblandet, såsom bygherre, landskabsarkitekter og anlægsgartnere, som alle skal nå til enighed. Ved at bruge cirkulære produkter kan der desuden opstå problematikker i hvem der skal stå til ansvar for kvaliteten af produktet.

Aesthetic

Æstetik

By using previously used products, there is not the same guarantee for a monotonous expression as with new products. There may be variations in colour, size and any visible damage that may give an unforeseen expression.

Furthermore, there is not always a guarantee that the desired product is available. However, there may also be a value in the patina that old materials achieve after use that new materials do not have. Aesthetics weighs heavily in landscape architecture, and previously used pavements can offer varied and unplanned appearances in an otherwise carefully designed project proposal.

Ved at benytte tidligere anvendte produkter er der ikke den samme garanti for et ensformigt udtryk, som ved nye produkter. Der er kan være variationer i farve, størrelse og eventuelle synlige skader, som kan give et uforudset udtryk. Ydermere er der ikke altid en garanti på, at det ønskede produkt er til rådighed. Dog kan der også ligge en værdi i den patina som gamle materialer opnår efter brug, som nye materialer ikke har. Æstetik vægter højt i landskabsarkitekturen, og her kan tidligere anvendte belægninger være et benspænd for et nøje designet projektforslag.

The good idea

Den gode ide

Without innovation, we cannot create a circular economy.

With the increasing scarcity of resources on raw materials and the high CO2-emissions of the construction industry, new ideas are required. Concepts and strategies must be developed for how more materials can be included in the circular rotation as well as how we can extend their lifespan. The report points to the relationship between extended lifespan and the possibility of maintenance as well as reuse and recycling of the product. But as in other aspects of the circular economy, there are complexities in the form of financial incentive and technical knowledge to develop new circular concepts and products.

Uden innovation kan vi ikke skabe cirkulær økonomi. Med den stigende ressourceknaphed på råmaterialer og byggeog anlægsbranchens høje CO2-udledning, er der brug for nytænkning. Der skal udvikles koncepter og strategier for hvordan flere materialer kan indgå i det cirkulære kredsløb samt hvordan vi kan forlænge deres levetid. Rapporten peger bl.a. på sammenhængen mellem forlænget levetid og muligheden for vedligeholdelse samt genbrug og genanvendelse af produktet. Men som i andre aspekter af cirkulær økonomi, findes der også her benspænd i form af økonomisk incitament og teknisk viden til at udvikle nye cirkulære koncepter og produkter.

Standards and certification

Standarder og certificering

Today it can be challenging to get previously used products incorporated into the existing certification schemes as well as the standards for building and construction. This is partly due to the fact that there is a lack of certification schemes and standards for previously used products.

With more flexible and dynamic standards, developments in circular solutions can be better met and established in the construction industry. It can also be an advantage to implement standards for documentation of where and how the material has been used in the past. In addition, requirements should be set for the service life of the materials, as well as its possibilities for repair, maintenance and recycling.

På nuværende tidspunkt kan det være udfordrende at få tidligere anvendte produkter indpasset i de eksisterende certificeringsordninger samt bygge- og anlægsstandarder. Det skyldes bl.a. at der er en mangel på certificeringsordninger og standarder på tidligere anvendte produkter. Ved mere fleksible og dynamiske standarder, kan udviklingen inden for cirkulære løsninger bedre imødekommes og etableres i anlægsbranchen. Det kan ydermere være en fordel at implementere standarder for dokumentation af hvor og hvordan materialet tidligere har været brugt. Desuden bør der sættes krav til materialernes levetid, samt dets muligheder for reparation, vedligeholdelse og genbrug.

Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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Legislation

Lovgivning

By implementing legal requirements for circularity and sustainable production, more companies will be motivated to research, develop and invest in circular principles. As long as the government does not make demands on the circular economy, more companies will generally choose the cheaper solution.

Ved implementering af lovkrav om cirkularitet og bæredygtig produktion, vil flere virksomheder motiveres til at forske, udarbejde og investere i cirkulære principper.

Så længe regeringen ikke stiller krav til cirkulær økonomi, vil virksomheder generelt vælge den billigere løsning.

Economy

Økonomi

It should not be underestimated that several of the issues in the circular rotation are rooted in economics. The processes of reusing, recycling and converting can be associated with more expenses than just buying a new product, where the cost-benefit analysis itself requires a lot of financial resources. Standards and methods on how to do so would promote financial motivation in entering the circular rotation.

Man skal ikke underkende, at flere af problemstillingerne i det cirkulære kredsløb bunder i økonomi. Ved mange materialer kan processerne i at genbruge, genanvende og genudnytte være forbundet med flere udgifter end blot at købe nyt. Denne opvejning kræver i sig selv mange økonomiske ressourcer. Derfor skal der udvikles standarder for hvordan man kan finde et økonomisk incitament til at indgå i det cirkulære kredsløb.

Knowledge sharing and attitude processing

Vidensdeling og holdningsbearbejdning

The circular economy is not a new concept, but until recently it has not been deliberately implemented in Danish landscape architecture. The language of the circular economy is not universal and there is a lack of knowledge sharing between the various actors. This has been a motivating factor for developing this report, wherein particular the diagram will promote a common understanding of the different stages in the circular economy. In order to accommodate circular solutions, it is necessary with a general attitude processing so that the circular choice becomes the obvious choice.

Cirkulær økonomi er ikke et nyt begreb, men det er indtil fornyligt ikke blevet bevidst implementeret i dansk landskabsarkitektur og anlægsbranchen. Sproget for cirkulært økonomi er ikke universelt, og der er en mangel på vidensdeling mellem de forskellige aktører. Dette har bl.a. været motivationen for udviklingen af denne rapport, hvor især diagrammet kan hjælpe til en fælles forståelse af de forskellige stadier i det cirkulære kredsløb. For at imødekomme cirkulære løsninger, er det nødvendigt med en generel holdningsbearbejdning så det cirkulære valg bliver det oplagte valg.

The Circular Properties of Materials in Landscape Architecture 2020-2021

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1

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12

Interview: Salg- og bæredygtighed Michelle Hansen, 1/12-2020, Zurface, København

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Alberte Caspersen Borup, bls326 & Nina Trock-Jansen, cxv308

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29

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39 Krull, L. & Brixen, P. (2019) Ny opskrift på cement sænker byggeriets CO2-udledning. Danmarks Tekniske Universitet 40 Trap Danmark, (2019), Det bornholmske grundfjeld - fra råstofressource til rekreativ naturområder. Trap Danmarks redaktion. https://trap.lex.dk/Det_bornholmske_grundfjeld_-_fra_råstofressource_til_rekreative_ naturområder [visited 10.01.2021] 41 Steen Jensen (no date) Stenbrydning. Steen http://www.steenjensen.dk/stenbrydning.5397.aspx [visited 10.01.2021]

Buchardt, B., Hoffritz, S.E. & Korshøj, J.S. (2019): Byens sten – guide til en geologisk byvandring i København. Geologisk Tidsskrift https://2dgf.dk/xpdf/gt2019-1-25.pdf [visited 10.01.2021] 42

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44 Klimatilpasning (2020) Linjedræn og render. Klimatilpasning. https://www.klimatilpasning.dk/viden-om/teknologi/hverdagsregn-og-skybrud/linjedraen-ogrender/ [visited 14.01.2021] 45 Zimmermann, A. (2015) Constructing landscape: Materials, techniques, structural components.

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