Concrete Magazine - Volume 61. Issue 02.

concrete VOLUME 61 ISSUE 2

SURFACE REGULARITY GUIDANCE DEVELOPED FOR CONCRETE FLOORS

NZ FOCUSSED SCM RESEARCH PROJECT WILL HELP REDUCE EMISSIONS FROM CONCRETE

THE MAGAZINE OF CONCRETE NZ

UPFRONT

concrete MAGAZINE

INNOVATIVE CEMENTS TO HELP REDUCE CONSTRUCTION EMISSIONS

Editor/Advertising: Adam Leach +64 4 915 0383 adam@concretenz.org.nz

THE NEW ZEALAND CONCRETE INDUSTRY HAS HIGHLIGHTED ITS RECENT SUCCESS IN REDUCING EMISSIONS ALONG WITH ITS VISION TO PROGRESS DECARBONISATION FURTHER IN RESPONDING TO THE CLIMATE CHANGE COMMISSION’S 2021 DRAFT ADVICE FOR CONSULTATION.

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by Concrete NZ

The Commission’s advice offers guidance to the Government on how to implement an emissions reduction plan, and will be key in helping New Zealand play its part in reducing emissions under the Paris Agreement.

Tel: +64 4 499 8820 Email: admin@concretenz.org.nz Website: www.concretenz.org.nz

While the Commission should be applauded for its efforts in drafting such a comprehensive document, it is in parts overly prescriptive in its guidance on lower-emissions pathways.

ISSN: 1174-9374 (online)

Concrete NZ considers the market is best placed to determine the most efficient approaches for emissions reductions, and recommended that government facilitates meaningful engagement with industry to understand regulatory and resource needs to achieve emissions targets.

Government support will also be required to modify building and infrastructure design tools to incorporate the carbon cost, and in turn, optimise design for carbon footprint.

Concrete NZ also urged that the design life for buildings be extended from 50 to 100 years, and that only cradle-to-grave-tocradle Life Cycle Assessments are used when selecting building materials for low-emissions construction.

EMISSIONS REDUCTION SUCCESS Demonstrating to the Commission that the New Zealand concrete industry walks-the-walk is the fact that independent consultants thinkstep have confirmed a reduction in emissions from cement of 15 percent between 2005 and 2018.

The 15 percent reduction in emissions was achieved through the use of alternative kiln fuels in cement manufacture and a general shift to more efficient manufacturing processes.

CONCRETE INDUSTRY VISION The Commission was also made aware that the concrete industry, under the Concrete NZ banner, has developed a vision which states that by 2030 it will have reduced its emissions by another 15 percent to achieve a 30 percent drop from 2005 levels.

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Subscriptions: Angelique Van Schaik +64 4 499 8820 admin@concretenz.org.nz

PO Box 448 Level 4, 70 The Terrace Wellington NEW ZEALAND

ISSN: 1174-8540

Disclaimer: The views expressed in concrete are not necessarily those of the Concrete NZ. While the information contained in the magazine is printed in good faith, its contents are not intended to replace the services of professional consultants on particular projects. The Association accepts no legal responsibility of any kind for the correctness of the contents of this magazine, including advertisements. © Copyright 2021 Concrete NZ Advertorial Cover image: Alexander Nasonov/Conset Construction Ltd.

This vision will be enabled through: • using efficient energy sources for manufacturing and delivery processes, • driving waste minimisation in manufacturing, delivery and construction, • developing recycling processes to minimise the use of virgin materials, • adopting new technologies where appropriate, • being engaged with our local communities; and • facilitating the increased uptake of low carbon supplementary cementitious materials (SCMs).

LOW CARBON CEMENTS The increasing global use of SCMs to replace cement and therefore directly reduce embodied carbon dioxide makes sound ecological sense.

SCMs are derived from lower embodied energy materials, and can result in environmental benefits, improved concrete performance, and long-term cost advantages.

Typically, they are ground granulated blast

furnace slag (waste from steel manufacture), fly ash (waste from coal combustion) or silica fume.

Industry is also working to enable the increased adoption of another type of SCM - natural pozzolans - or rather volcanic ash from New Zealand’s North Island Volcanic Plateau.

To help enable a better understanding and greater uptake of both industrial and natural SCMs, Concrete NZ is undertaking research, supported by the Building Research Levy, to assess classification techniques along with the fresh and hardened performance of SCM concrete – see pages 16-18.

Concrete NZ’s work in this area is important as the increased use of SCMs as a replacement for cement clinker will be important to the concrete industry reaching its emissions reduction target of 30 percent by 2030.

Ngā mihi, Rob Gaimster Concrete NZ Chief Executive

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CONCRETE NZ CONFERENCE 2021 AFTER BEING FORCED TO CANCEL THE 2020 EVENT DUE TO THE COVID-19 PANDEMIC, CONCRETE NZ IS PLEASED TO ANNOUNCE THAT ITS 2021 CONFERENCE IS LOCKED-IN FOR 14-16 OCTOBER AT THE ENERGY EVENTS CENTRE IN ROTORUA. Rotorua is widely-considered to be one of New Zealand’s top tourist destination – the city boasts a remarkable range of attractions and activities catering to diverse interests and abilities.

Positioned at the edge of Lake Rotorua, the Energy Events Centre is located within the Government Gardens and is also a short walk away from the retail precinct, accommodation, restaurants, cafes and spa facilities.

The annual Concrete NZ conference is an excellent opportunity for members and nonmembers to keep abreast of recent developments across a range of concrete design, construction, manufacturing, materials and innovation topics, which combine to make for a stimulating conference technical programme.

Professor Santiago Pujol, from the University of Canterbury, has been secured as the keynote speaker for the 2021 event, and will share

his fascinating experiences testing concrete structures around the world.

As a modern venue, the Energy Events Centre offers plenty of room for trade stands, while ample space directly outside is ideal for displaying heavy equipment and vehicles, as well as conducting live demonstrations.

The conference retains the same format as previous years: The technical programme begins midday on Thursday 14 October, runs into Friday morning and concludes around 1:00 pm on Saturday. The welcome dinner takes place on Thursday evening, with Friday afternoon reserved for a range of social activities, and the formal conference dinner and Awards taking place on Friday evening.

Concrete NZ looks forward to seeing you in Rotorua 14-16 October.

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W www.theconcreteconference.co.nz

CONFERENCE 2021

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Images: Conslab Ltd.

CONCRETE NZ FLOOR GUIDANCE LOOKS AT SURFACE REGULARITY Dave McGuigan, Technical Director, Concrete NZ Concrete floors may appear basic but all aspects of their design, construction and maintenance should remain top-of-mind to achieve long-term functionality.

This is particularly important as inadequate surface regularity increases the risk of collision between materials handling equipment, such as forklifts and high-level racking.

The requirements of building users have evolved considerably over recent decades.

This may mean the materials handling equipment needs to operate at slower speeds, reducing efficiency of operations.

At the same time, construction methodologies have also advanced, meaning that some content in existing guidance documents, such as NZS 3114:1987 Specification for Concrete Surface Finishes, is not always suitable.

At first glance a concrete floor may appear a simple structure, however there are many aspects such as surface finish, equipment and vehicle loadings, underlying soil conditions, structural design, concrete properties, construction methods and joint layout that all require careful consideration.

One aspect that Concrete NZ, in consultation with industry experts, felt needed to be bolstered in terms of guidance was surface regularity – a floor’s ‘flatness’ and ‘levelness’.

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Materials handling equipment is also becoming increasingly automated, placing even greater emphasis on achieving flat and level floors.

Working with industry, Concrete NZ has developed Technical Specification 01:2021 - Surface Regularity Requirements for Concrete Floors, which can be applied to internal concrete floors that are either supported by the ground or are suspended.

The document includes provisions that can apply to a range of building uses including industrial, warehousing, retail or office, where different tolerances are required for the specific use, such as high reach forklifts, and/or take account of final floor finishes that may be applied, such as tiles.

Concrete NZ has also included guidance on methods for measuring surface regularity.

The document was introduced to industry via a Concrete NZ Learned Society seminar series across the three main centres in late March and early April.

The seminars targeted designers, specifiers, consulting engineers, local authorities, and contractors.

Concrete NZ was very interested in the attendees’ response to the new document, as well as their feedback on other areas of concrete floor design, construction and maintenance that may benefit from further technical guidance.

Technical Specification 01:2021 - Surface Regularity Requirements for Concrete Floors is available to download from the Concrete NZ website – www.concretenz.org.nz

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CONCRETE NZ CONGRATULATES ENGINEERING NZ FELLOWS ENGINEERING NEW ZEALAND (ENZ) CELEBRATED ITS 2021 FELLOWS, DISTINGUISHED FELLOWS AND AWARD WINNERS AT A PRESTIGIOUS GALA DINNER HELD RECENTLY IN WELLINGTON. Representing the pinnacle of the engineering profession, those acknowledged also included 2020 recipients, who due to COVID-19 were unable to be recognised at an event.

Amongst those receiving applause for their inspiring achievements and service were Des Bull, Dr Nicholas Brooke, Alessandro Palermo and Americo dos Santos.

DISTINGUISHED FELLOW Des Bull DistFEngNZ, CPEng Desmond Bull is elected a Distinguished Fellow of Engineering New Zealand for his contribution to structural engineering practice.

Des has held senior roles in the profession, including Technical Director of Holmes Consulting and the Holcim Adjunct Professor of Concrete Design at the University of Canterbury. He was a driver for creating a USAR engineer service in New Zealand, the importance of which became clear in the aftermath of the February 2011 Christchurch earthquake.

graduation. His plain-speaking and obvious commitment to address issues within engineering practice has made him highly respected by his peers. Des is a role model, extolling the ethos of lifelong learning for himself and his students.

Des’s commitment to professional excellence has been widely recognised. He is a life member of SESOC, an honorary life member of the Concrete New Zealand Learned Society, a fellow of the New Zealand Society for Earthquake Engineering, and a previous recipient of the Engineering New Zealand Professional Commitment Award.

Des displays a passion for structural engineering and the advancement and dissemination of structural engineering knowledge. He has the ability to bridge research, academia and consultancy in a very practical way. His teaching and research benefit immeasurably from his intimate link to practice. This is especially evident in Des’s research, which invariably focuses on key issues facing industry. Des has made major contributions in several areas, perhaps most notably in the analysis and design of floor diaphragms and was pivotal in identifying and publicising the potential poor performance of some precast concrete floor systems.

Des has been a regular presenter of industry training seminars and a major contributor to the New Zealand Standards for Concrete Structures and Seismic Design Actions for almost 30 years, as well as being the author or editor of many widely used national and international guidance publications.

Another hallmark of Des’s character is his passion for acting as a mentor to countless undergraduate and postgraduate engineering students, with this often continuing after their

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Des Bull acknowledges those in attendance as he is elected an Engineering New Zealand (ENZ) Distinguished Fellow

FELLOWS Nicholas (Nic) Brooke Dr Nicholas Brooke specialises in the technical aspects of structural engineering, particularly for concrete structures. He is regularly engaged as an expert witness, having provided advice on many of New Zealand’s largest earthquake-damage insurance claims. Nicholas is heavily involved in SESOC, is the current Concrete NZ Learned Society President, and a regular contributor to the development of technical guidance and Standards. He remains actively engaged in research, with his recent work focused on improving existing precast concrete floors and the reparability of buildings after earthquakes.

Nic Brooke is recognised as an Engineering New Zealand Fellow by Chief Executive Richard Templer

Alessandro Palermo

Richard Templer, Chief Executive of Engineering New Zealand, presents Alessandro Palermo with his Engineering New Zealand Fellow certificate

Alessandro Palermo is a professor of structural engineering at the University of Canterbury who is recognised for the quality of his research and teaching. Popular with students, his infectious enthusiasm for teaching has meant a number of awards, including five University Student Union (UCSA) Awards and a University of Canterbury teaching award. His research expertise is focused on finding seismically resilient solutions for bridge and building structures and has been published, cited and widely recognised through national and international awards. It has also led to innovation in partnership with industry. Alessandro is the Concrete NZ Learned Society Vice President.

Americo dos Santos

Americo dos Santos receives his Fellow certificate from Colin Crampton, Engineering New Zealand President

Americo dos Santos is the Technical Services Manager for Hynds Pipe Systems, with over 40 years’ experience. He is an expert in the design, manufacture and installation of precast concrete pipe and drainage structures. His contribution to engineering includes training, addressing industry issues, and developing and marketing innovative precast concrete products. Dos is an active member of the Standards Australia Concrete Pipes Committee, the Concrete Pipe Association of Australasia and Concrete NZ’s Precast Sector Group. Dos has been a key influence in many technical notes, guidance documents and papers regularly referenced by engineers, as well as the development of safe work practices.

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COUNTING THE 80s & 90s MUSIC BEAT OF CONCRETE BATCHING AT STRESSCRETE’S PAPAKURA PLANT IN AUCKLAND, YOU WILL FIND BATCHER NEVILLE DE RIDDER IN HIS CONCRETE CONTROL TOWER, DAY-IN AND DAY-OUT, CAREFULLY MONITORING MATERIALS TO CREATE THE PERFECT MIX FOR A RANGE OF PRECAST PRODUCTS. Stresscrete is one of New Zealand’s pre-eminent precast manufacturers. With over fifty years in the precast industry, they offer vast experience in the design and manufacture of engineered precast concrete components from precast panels to prestressed flooring.

Seeing similarities between working on a farm and at a concrete plant, Joe took on the young and enthusiastic Neville, and the rest is history.

Reporting for duty the very next day, Neville has worked in the concrete (and construction) industry ever since.

Operating plants in Papakura and Otaki, Stresscrete has around 160 employees, and over the years have supplied some of New Zealand’s most iconic structures, including the Beehive and Westpac (now Sky) Stadium in Wellington, and the Sky Tower and Central Motorway Junction (Spaghetti Junction) upgrade in Auckland.

You name it, Neville has done it - making moulds, spinning pipes and poles, working the casting bed, and of course, batching concrete. Transferring from Kaitaia to the Papakura plant in 1997, Neville found his utimate ‘concrete calling’, and now totals more than 54-years of duty.

Neville is one of three concrete batchers on the Stresscrete’s team, and there isn’t much he hasn’t seen in terms of technological and cultural change over the past five decades.

Hailing from Kaitaia, Neville left school when he was 14 to work as a farmhand. A few years later in 1966, at the age of 17, he applied for a job at Kaitaia Concrete and vividly remembers the interview with Joe Clough, Kaitaia Concrete’s no nonsense Managing Director.

What Neville enjoys most about batching concrete is the demand for consistency. He works methodically and with precision to combine constituent materials into the specified mix.

Audited by the Concrete NZ Plant Audit Scheme, Stresscrete currently batches concrete for its own use. Neville lays down around 60 to 100 cubic metres a day, which is delivered around the facility to create a range of products.

Back in the day, Neville would be out in the open,

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Neville De Ridder batches concrete at Stresscrete’s Papakura plant in Auckland, and has a keen eye for detail and a good ear for a catchy tune.

pulling levers and watching the scales drop material into the back of the truck – “The good old days,” Neville recalls with a smile.

Scott Mulholland, Stresscrete’s Technical Manager, echoes Neville’s sentiments in terms of the company’s values.

The introduction of computerised batching systems is clearly remembered by Neville as the most significant technological development during his working life.

“At Stresscrete we are a tight-knit team,” says Scott. “We have a number of staff who have been with us for over 40 years, which speaks volumes about the company.“

What was once performed ‘by-hand’ became automated, and while Neville feels a tinge of nostalgia this was a chance to refine his craft and strive for the perfect batch.

While Neville’s plans do not include retirement, they do include hopping into his campervan with his partner and driving around the North Island.

Catching-up with family and friends is a priority, as is fishing.

Neville relishes the opportunity to mentor his younger colleagues on the rhythm of batching, but he does not plan on retiring any time soon.

In addition to the professional satisfaction Neville gets from batching, being part of the Stresscrete team culture is hugely fulfilling.

In the meantime, you can find Neville in his concrete control tower, humming hit tunes from the 1980’s and 90’s, while batching quality concrete.

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Hon David Parker, Minister for the Environment and Fletcher Building CEO Ross Taylor officially open the upgrade at Golden Bay Cement’s Portland plant.

GOLDEN BAY CEMENT PROVIDES SUSTAINABLE DISPOSAL SOLUTION FOR WASTE TYRES FLETCHER BUILDING RECENTLY ANNOUNCED THE COMPLETION OF ITS TYRE PROJECT AT GOLDEN BAY CEMENT, WHICH WILL AVOID UP TO THREE MILLION USED TYRES GOING TO LANDFILL EACH YEAR TO INSTEAD BE USED IN CEMENT MANUFACTURING. The significant upgrade to New Zealand’s only end-to-end cement plant, which is based in Portland, Whangarei, was officially opened in late March by the Honourable David Parker, Minister for the Environment.

“This innovative project is a win-win-win for the environment. It reduces a significant waste problem, reuses a valuable resource, and reduces carbon emissions by about 13,000 tonnes a year,” Environment Minister David Parker said.

Fletcher Building CEO Ross Taylor says this is a landmark sustainability project for manufacturing in New Zealand.

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“Using end-of-life tyres in cement manufacturing helps to solve a significant waste problem in New Zealand as well as improve the sustainability of a key building material. Up to 50 percent of the 6.3 million waste tyres created in New Zealand each year will now be used in cement manufacturing at the Golden Bay Cement plant instead of going into landfill.

“There are no other large industries in New Zealand that can readily or cleanly consume the volume of waste tyres our Portland cement plant can.

“Waste tyres have been used successfully in many cement plants throughout the world. We are

proud to bring this world-leading technology to New Zealand as well as our investment in local manufacturing jobs and capability.

“The project was a significant investment over several years that involved upgrades to the plant, with specialist equipment from Denmark installed to feed the tyres into the cement manufacturing process. With the upgrades now completed, we have been successfully using tyres since 22 February. The tyres are combusted at around 1,400°C and the rubber, metal and any ash are combined into the cement.

“Golden Bay Cement supplies more than half the New Zealand market as the only local cement manufacturer.

“Our cement already has around 20 percent lower emissions than imported cement and using tyres is part of the decarbonization plan to reduce its footprint even further. It will also reduce our need for natural raw materials like iron sand.

“Local manufacturing must compete fiercely with imports, and this investment allows us to continue doing just that. At the same time, we’re providing local jobs as well as supply chain security for the domestic building, infrastructure, and construction industries,” said Ross Taylor.

Fletcher Building has a verified science-based target to reduce its emissions by 30 percent by 2030.

Ross Taylor said, “Climate change is an urgent, global priority. The building and materials sector has an important role to play by changing the way that it designs, builds, sources, and manufactures the building materials used in the construction process. We are serious about transforming our business around sustainability to do our part in creating a sustainable future and reducing our carbon emissions.”

The Ministry for the Environment part funded the $25 million project with a grant of $16 million awarded through its Waste Minimisation Fund.

Golden Bay Cement’s use of waste tyres will: • Use up to 3.1 million shredded waste tyres • Reduce coal use by 15 percent • Reduce iron sand use by 5,000 tonnes • Reduce carbon emissions by around 13,000 tonnes

Hon David Parker, Minister for the Environment is given a tour of the Portland plant by Ben Walsh, Golden Bay Cement’s Manufacturing Manager.

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New research at UC led by Structural Engineering Professor Alessandro Palermo (right) has highlighted the impact deterioration can have on the performance of structures. PhD student Cain Stratford (left) is investigating how GFRP bars may be used in reinforced-concrete bridge columns.

A NEW SOLUTION FOR AGEING, CORRODING INFRASTRUCTURE SURROUNDED BY OCEAN, MOST OF NEW ZEALAND’S REINFORCED-CONCRETE INFRASTRUCTURE LIES CLOSE TO THE COAST, MAKING IT SUSCEPTIBLE TO CORROSION. COULD NEW GLASS-BASED REINFORCING HOLD THE ANSWER? Research at the University of Canterbury (UC) led

by Structural Engineering Professor Alessandro Palermo has highlighted the impact deterioration can have on the performance of structures. This research is important, especially given recent deadly bridge failures, such as the Morandi bridge in Italy, which collapsed due to corrosion and structural weakness, killing 43 people in 2018.

Safety is key in bridge design, but what about ongoing costs associated with the repair and rehabilitation of ageing infrastructure?

“The way we build our future infrastructure should be more sustainable and not only limited to the construction carbon footprint,” Professor Palermo says. “In the next 30 to 50 years, we will have more people, more bridges and probably less money to maintain our infrastructure. We need to look forward and opt for more durable materials.

This will significantly reduce maintenance costs and increase structural life-cycles.”

One alternative gaining international interest is the use of non-metallic reinforcing bars. Glass FibreReinforced Polymer (GFRP) bars have proved to be a promising substitute for steel reinforcement in structures subject to harsh environments.

Corrosion-free, they have higher tensile strength than steel with only a quarter of the weight.

University of Canterbury PhD candidate Cain Stratford is investigating how GFRP bars may be 14 concrete

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used in reinforced-concrete bridge columns to achieve a superior design life for the bridge, while maintaining sufficient seismic performance.

“Construction of the columns was made noticeably easier by the lightweight nature of the GFRP bars. The experiment has been designed to simulate the loading that a bridge pier may be expected to withstand during a seismic event.

Initial results from our tests have shown that a combination of GFRP bars with conventional steel can be an optimum choice to guarantee both excellent seismic performance and an increase in the usable life of the structure,” Stratford says.

“I believe that the outcomes of this study will result in a major design shift in the field of bridge engineering, with structural application soon in New Zealand,” Palermo says.

Last year, the University of Miami published Durability of GFRP Bars Extracted from Bridges with 15 to 20 Years of Service Life showing that the GFRP rebars maintained over 97 percent of their original strength with no sign of corrosion. The University has been studying the extremely high durability of Mateenbar, manufactured by New Zealand company, Pultron Composites.

Callaghan Innovation sponsored the PhD programme aiming to increase the use of GFRP rebars in New Zealand.

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SCM RESEARCH 1.

LITERATURE REVIEW AND EXPERIMENTAL PROGRAMME James Mackechnie, Education, Training & Research Manager, Concrete NZ IN NEW ZEALAND THERE HAS BEEN A 15 PERCENT REDUCTION IN CARBON EMISSIONS ASSOCIATED WITH PORTLAND CEMENT PRODUCTION SINCE 2005 EVEN THOUGH CONCRETE PRODUCTION INCREASED BY 13 PERCENT DURING THE SAME PERIOD. This has been achieved by better process efficiencies at existing cement factories and by replacing less efficient production facilities. Kiln efficiency at local cement factories has been achieved by utilising waste materials such as biomass and vehicles tyres that reduce coal consumption and by adopting advanced process control measures.

Combining the good practices in cement kiln efficiency and process control with better use of Supplementary Cementitious Materials (SCMs) could reduce NZ carbon emission by a further 15 percent by 2030. Achieving this target will require a better understanding of how industrial and natural SCMs can be best used in concrete construction.

Tracking this projected shift in emissions will be relatively simple to measure given the clear manner that production levels are recorded with minimal wastage in the process.

SUPPLEMENTARY CEMENTITIOUS MATERIALS SCMs are either sourced from industrial wastes such as fly ash, ground granulated blast-furnace slag (GGBS) and silica fume or from natural materials that are beneficiated into pozzolans such as pumicite, micro-silica, diatomite and calcined clays such as metakaolin. SCMs have diverse chemical and physical properties that affects their reactivity and interaction with PC. The range of chemical compositions of cementitious materials is shown in Figure 1 below.

SiO2 Silica fume Natural pozzolans

S5 S4

S6

Blast-furnace slag

Fly ash (ASTM Class F)

S3 S2

Fly ash (ASTM Class C) S1 Portland cement

Figure 1: Ternary diagram showing chemical composition of Portland cement and SCMs

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Metakaolin/ calcined clay

SCMs made from industrial waste such as fly ash, GGBS or silica fume are widely used in countries with a strong industrial base where these waste materials are generated. These materials have been used in concrete for more than 50 years and the performance of blended cements in concrete is well understood although characterisation techniques are still improving with better understanding.

The geology of New Zealand does have significant resources of natural pozzolans and clay minerals, which include the following: • Pumice deposits that can be ground to form pumicite that has been shown to have similar reactivity to that of fly ash.

• Amorphous silica in the Rotorua region that have in the past been able to provide very high reactivity similar with silica fume.

• Tuff and ignimbrite resources that are widespread and have reasonable reactivity as SCMs by being partially amorphous and microporous.

• Kaolin deposits that when contaminated with iron and/or magnesium cannot be used as pigments and fillers but could theoretically be activated at moderate temperatures (e.g.

700 0C) to form metakaolin.

• Other reactive silica sources such as diatomaceous earth that have shown promise when tested in the 1980’s and 1990’s but may be difficult to extract due to concerns about silica dust.

Natural pozzolans are primarily alumino-silicates or amorphous silica that react with hydroxyl ions in concrete to produce secondary pozzolanic reactions. Four main types of natural pozzolan may be defined and found in New Zealand: • Volcanic glass deposits of pyroclastic origin that include non-consolidated volcanic ash and pumice with variable pozzolanic activity depending on their siliceous content and fineness (e.g. pumice and volcanic ash).

• Amorphous silica from either biogenic or hydrothermal activity that form relatively soft clastic rock types such as diatomite or amorphous silica deposits (e.g. diatomaceous earth and amorphous silica).

• Zeolites produced by lithification of volcanic glass deposits that are partially transformed from amorphous to crystalline but still retains pozzolanic activity due to their microporous nature (e.g. tuffs and ignimbrite).

• Clay minerals such as bentonite or kaolinite that are very mildly reactive but can be made significantly more reactive when calcined at 700-800 0C (e.g. metakaolin or calcined clays).

10,000

New Zealand geological resources are well documented 60 years ago by the Department of Scientific & Industrial Research (DSIR). Kennerley and Clelland from DSIR investigated a wide range of natural pozzolans including rhyolite, pumicite, ignimbrite, andesite tuff and basaltic tuff. Testing included petrographic examination, chemical analysis, mortar and concrete tests of blends of cement and pozzolan. Reactivity of natural pozzolans in New Zealand was found to increase with fineness and glass content as shown in Figure 2 below.

90%

Strength Ratios 90 days at 21oC

9,000 8,000

Fineness (cm2/g)

6,000

80%

72

7,000 59

79

64 73

93

83

81 58

76

69

70%

5,000

70

60

71 64

4,000 3,000

60%

2,000 1,000 0

Andesite or tuff 0

Ignimbrite Pumice sand or rhyolite 10

20

30

40

50

Pumicite 60

70

80

90

100

Glass Content (%) Figure 2: Strength ratios of mortar made with 35% replacement of natural pozzolans

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CHARACTERISATION OF SCMS

EXPERIMENTAL PROGRAMME

The quality of Portland cement is characterised primarily by the strength performance of mortar or concrete samples made from the material.

The chemical and physical properties of Portland cement have a significant bearing on this hardened performance and modern cements tend to fall within a narrow range and the cement hydration reaction is predictable giving reliable and repeatable results. When SCMs are considered using a similar classification system, performance of concrete becomes more difficult to predict. The poorer correlation between strength activity index testing and concrete strength for SCM concrete is due to the following:

An experimental program was developed in 2020 to investigate how best to utilise SCMs in concrete construction, with the following key concerns:

• Portland cement has consistent density values whereas SCMs may be considerably lighter than cement such that replacement levels cannot be made based on weight but should be done by volume.

• Classification tests are generally done on mortar mixes where no chemical admixtures are used to compensate for the higher absorption of some pozzolanic materials, which leads to variable water/binder ratios during the test.

• Testing age is typically at 28 days, which tends to favour more reactive SCMs and often means that more slowly reactive natural pozzolans thatgain more long-term strength are excluded.

• Mortar cubes are cast at relatively lower consistence levels (almost dry mixes) that means that some binder combinations are difficult to compact properly and result in excess void contents in hardened mortar.

• Better classification systems for potential SCMs to complement existing methods.

• Assessing fresh properties of SCM concrete including bleed, setting and workability.

• Strength development and durability performance of SCM concrete.

• Benchmarking of typical performance using industrial SCMs such as fly ash or slag.

To undertake this experimental work the following materials were investigated and provided a wide range of reactivity and performance (see Figure 3): • Two sources of GP cement for standard concrete mixes.

• Two sources of HE cement for higher strength mixes.

• Two types of fly ash (ASTM Class F and Class C) • Blast-furnace slag from Australia.

• Perlite and natural pozzolana from New Zealand.

• Calcined clay using moderate grade kaolinite (55 percent) from New Zealand.

Research was started on this experimental programme at the University of Canterbury in June 2020 and the results of this testing will be discussed in the next issue of Concrete magazine. This follow up article will focus on how best to characterise and classify SCMs so that their performance in concrete can be accurately predicted.

Portland GP Cement

Huntly fly ash (S2)

Adani fly ash (S3)

NZ Pozzolana (S4)

Ground perlite (S5)

Calcined clay (S6)

Figure 3: Portland cement and SCMs used in research programme

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Your building could be put to the ultimate test.

So we do the same to our steel.

At Pacific Steel, we put all our products through a rigorous testing regime. Our dedicated laboratory has full IANZ certification and we’re the only local manufacturer of reinforcing steel to have third party ACRS certification. So when we say our SEISMIC® reinforcing steel is tested to meet the AS/NZS 4671 standard, you can be sure it’s been put to the ultimate test.

A steel bar about to be tested in one of five testing machines at our laboratory in Otahuhu.

PAC0015CCT

COMBATING COASTAL EROSION BLOCK BY CONCRETE BLOCK RISING SEA LEVELS CAUSED BY CLIMATE CHANGE POSE A THREAT TO COASTLINES AROUND THE WORLD. HOPE IS AT HAND HOWEVER, IN THE FORM OF AN INNOVATIVE PRECAST CONCRETE SOLUTION MADE RIGHT HERE IN NEW ZEALAND. Westlock Concrete Solutions Ltd (WCS), based in Northern Buller on the West Coast of the South Island, decided that it was time to stop retreating and start advancing!

“I was looking for a long-lasting fix,” says Martin.

“So, I began to collaborate with a group of local residents, which fortunately included several engineers.”

With the aim of protecting New Zealand’s vulnerable coastline from the rising tide, the small Kiwi company has designed and constructed a trial seawall of interlocking hexagonal concrete blocks at Hector, 30 kilometres north of Westport.

Following much discussion WCS was established, and its collective experience and expertise led to the interlocking block design.

BACKGROUND Martin Hill, WCS’s Director of Sales and Marketing has first-hand experience of the damage caused by coastal erosion. After several attempts at protecting his own property with large boulders, he realized it did not offer a long-term solution.

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As the development process reached the engineering compliance and manufacturing stages, WCS partnered Busck Prestressed Concrete Ltd, one of New Zealand’s largest and most respected manufacturers of precast concrete products.

The outcome was an engineered interlocking hexagonal block, which when combined with the

appropriate placement method creates a versatile and durable structure that offer over 50 years of protection against the unrelenting ocean.

ensure compliance with the marine requirements of class C in NZS 3101 Concrete Structures Standard for a 50-year life,” says Marshall.

Research and development undertaken by WCS paid dividend during manufacturing and installation.

The blocks also have a concrete strength of 45 MPa, a F4/U3 surface finish, a minimum reinforcing cover of 60 mm, and returns as specified in NZS 3101.

“There is a lot more to the product than meets the eye, and with the help of Busck, we have created a very high-specification marine grade concrete block,” says Martin.

“The partnership is working very well, with Busck providing the design certification and manufacturing component, and WSC the concept, installation and marketing.” says John.

Busck acknowledge that making the blocks was relatively simple, thanks to WCS’s attention to detail during pre-production trials.

INSTALLATION AND RESPONSE

MANUFACTURING CONSIDERATIONS

“WCS ironed out a lot of creases during their early development work,” says John Marshall, Busck’s National Technical & Design Manager. “This combined with their willingness to share information about the challenges they had overcome meant we didn’t have to reinvent the wheel.”

The trial seawall, located near the tiny West Coast town of Hector, was built in a week using a single 12-tonne excavator.

The seawall consists of three different block types (base, standard and top), is five blocks high and 40 blocks long, totalling around 200, 2-tonne concrete blocks.

Busck conducted its own trials at its Ashburton factory, which used in-house draughting and 3D modelling capability to experiment with reinforcing content and with different ways of connecting the blocks to maximize resilience.

There were no issues in terms of gaining consent, with the West Coast Regional Council, along with the Department of Conservation, seeing tremendous potential in the system’s ability to combat coastal erosion.

“The concrete used in the blocks themselves has a low water/cement ratio and contains micro-silica to

Of particular appeal to the Council is that the system requires minimal maintenance, unlike

Westlock Concrete Solutions Ltd (WCS) and Busck Prestressed Concrete Ltd are rightfully proud of their interlocking concrete seawall system.

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the current practice of arranging large boulders to form temporary barriers, which in storm conditions can pose a danger to homes.

The community response to the trial wall has been very positive, with plenty of offers to assist during installation, as well as many admiring glances now that it is complete.

NEXT STEPS The local community’s interest has been matched from further afield, with inquiries received from along the West Coast and around New Zealand, a response helped by 1 News filming a story on the ‘clever concrete invention’.

WCS hope that the success of the trial seawall will prompt regional, district and city councils to seriously consider the system in plans to address coastal erosion.

The return on investment from the WCS system is clear, with the value of properties in areas

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prone to the loss or displacement of land always under threat.

Furthermore, the peace-of-mind offered through a permanent solution to coastal erosion also encourages the development of surrounding areas, making for a win-win situation.

The economics are bolstered by the fact that Busck can manufacture the blocks at any of its seven facilities across New Zealand, from which transport to site can either be by truck or rail.

“Climate change will inevitably accelerate the rate of coastal erosion across New Zealand, creating a lot of stress for property owners and councils alike,” says Martin.

“WSC will look to raise awareness of the interlocking block system with territorial authorities and central government as well as amongst civil engineers, to ensure every erosion affected New Zealander has the option of a longterm solution.”

Images: Stephen Goodenough Photographer

PRECAST DELIVERS STYLE, FUNCTIONALITY AND AFFORDABILITY TO NEWBUILD TOWNHOUSES AN ARCHITECTURAL AWARD-WINNING PROJECT IN PETONE (WELLINGTON) HAS EMPHASISED THE VERSATILITY AND SUITABILITY OF PRECAST CONCRETE FOR MULTI-UNIT, MEDIUM-DENSITY RESIDENTIAL NEWBUILDS. Located on a 7,851 m2 site at the eastern end of Jackson Street, the 56-dwelling Paetutu townhouse project was constructed for client Taranaki Whanui and developer The Wellington Company by Homestead Construction via plans drafted by CoLab Architecture.

Homestead Construction project manager Zane Bull says precast concrete was the “perfect fit” for the development, which features units ranging from 72 m2/two-bedroom to 78 m2/threebedroom dwellings.

“It allowed for speed of construction – the precast structural components were manufactured offsite, and could be installed onsite in just a few days,” he says.

“The concrete has also helped with passive fire protection, as well as being an effective sound barrier for intertenancy walls.”

Furthermore, Zane says the precast proved capable of serving as an attractive design element both internally and externally on a number of the units.

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“It was used as a feature wall inside some of the homes, while others showcased a plain off-theform finish or an imprinted timber grain finish on the exterior.

“Ensuring the units that presented concrete externally had a consistent look across the 12 different blocks meant pouring them all within a few weeks of each other.”

Zane says this development aligned seamlessly with Homestead Construction’s experience and expertise, and further enhanced the working relationship established with the developer and its team over previous projects.

“Homestead prides itself on rapid construction, which when applied to multi-unit developments really benefits the client.”

Having “cut its teeth” on townhouse developments in Christchurch, CoLab Architecture was introduced to the project after a representative of the client, The Wellington Company, sighted some of the firm’s previous work.

“The Wellington Company reached out to us for the Erskine Development in Island Bay, where we

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worked with Homestead Construction for the first time, which then led to the Paetutu opportunity,” recalls Tobin Smith co-director of CoLab. The Paetutu project is one his firm is “very proud of,” says Tobin.

“Architecturally it’s clearly a success, while from a ‘social’ perspective it puts people into home ownership, and ‘morally’ it reunites whānau of the Taranaki Whanui with their historic land.

“The biggest challenge with any project is the fine balance between the desired yield, architectural and build quality, and of course the budget.

“Fortunately, in this instance, we were able to work with Homestead Construction very early in the piece to ensure variation and movement in the building forms and use of precast concrete, while at the same time guaranteeing that the outcome was truly affordable to iwi and ultimately the wider market.”

Tobin says developments such as Paetutu are “absolutely critical” to tackling New Zealand’s housing shortage and affordability issues.

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“Land is our most valuable natural asset, and as construction will most likely continue to get more expensive, building a new house will become moreand-more unaffordable for the majority of people.

“A project like this creates efficiency in land use as well as construction, which makes the outcome affordable without compromising quality.

“The model of Paetutu is particularly good in my eyes, as it still gives each occupant a house with land connection, meaning that every house has a private courtyard garden – as opposed to a vertically-stacked apartment model.”

Zane adds that multi-unit, residential developments are becoming increasingly commonplace in

Homestead Construction’s work programme.

“We have a number of exciting projects in the pipeline, all of which showcase the benefits of precast concrete construction.”

The Paetutu project earned CoLab one of only two Wellington Architecture Awards bestowed in the Housing – Multi Unit category by the New Zealand Institute of Architects (NZIA) in 2020.

“The feedback we’ve received from the client, occupants and the wider community has been incredibly positive,” continues Tobin.

“In fact, so has the feedback we’ve received from the architectural community, so we’re very happy.”

ARCHITECTURAL RECOGNITION CoLab Architecture’s work on the Paetutu development was acknowledged in 2020 by the New Zealand Institute of Architects (NZIA).

The official awards site provides the following statement on the project: A long history led to the recent opportunity for an iwi/development company community housing development on the historic site of Paetutu Kainga. Successful site planning balances the public realm with the private facilities for each townhouse. Textured and robust materials – timber and concrete – are used with highly-controlled detailing. Cultural placemaking is a wellintegrated design feature; the path through the community of two- and three-storey dwellings to the river’s edge is lined with artworks that tell the story of Rona and te Mārama (the moon).

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Images: Andre Vroon Photography

SUCCESSFUL PARTNERSHIP BUILT AROUND PRECAST CONCRETE HOMESTEAD CONSTRUCTION PARTNERED WITH KĀINGA ORA – HOMES AND COMMUNITIES TO DELIVER A MULTI-UNIT RESIDENTIAL DEVELOPMENT IN CANNONS CREEK (PORIRUA) AND PROVIDE TENANTS A GREAT PLACE TO CALL HOME. Utilising precast concrete, the development incorporates 14 one-bedroom units in two double-storey blocks built on vacant land at 178180 Champion Street.

“This was our first project with Kāinga Ora and, after early discussions, they approached us to manage both the design and build,” says Homestead Construction project manager Zane Bull.

“Construction commenced in early 2020 and was completed in nine months – one month ahead of programme.

“The use of precast concrete was hugely important to the speed of the build as well as providing both inherent fire resistance and a sound barrier between units.

“Furthermore, we turned the precast concrete into a feature on the exterior of the units – the walls have vertical grooves instead of a flat finish.

“Homestead Construction is always delighted to be involved with projects that assist in providing low-maintenance, affordable, healthy and durable homes for residents in Porirua.”

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Kāinga Ora project manager Matthew Serle says a standard procurement process was followed ahead of the development, with Homestead Construction selected “based on these practices”.

“Providing warm, dry, and healthy homes is incredibly important to Kāinga Ora as well as ensuring they meet our sustainability outcomes,” he says.

“The units are all built to a 6 Homestar rating, meaning they are comfortable, weathertight and energy efficient.

“The comments received have been very encouraging. Our tenants have noted just how warm and cosy their new homes are. Location and accessibility to public transport is another feature to receive praise.”

Matthew says the topography of the site needed to be accommodated in the design process.

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“Significant retaining was required to form building platforms for the rear portion of the site.

“The project made use of valuable public land to provide housing supply in a high-demand onebedroom configuration that meets the wider community’s needs.”

Matthew adds that precast concrete proved an ideal material for the development, for which Designgroup Stapleton Elliott served as architect.

“It is generally accepted as a cost and timeeffective method of construction, being very strong and durable with minimal maintenance.

“The availability of new housing is a key issue for both Wellington and New Zealand at present, and well-designed and high-quality, multi-unit developments are a hugely important way of achieving this increase in housing supply.”

STEP CHANGE FOR HOUSING AND URBAN DEVELOPMENT Established in October 2019, Kāinga Ora – Homes and Communities is regarded as marking a step change in housing and urban development in New Zealand.

Bringing together the people, capabilities and resources of the KiwiBuild Unit, Housing New Zealand and its development subsidiary HLC, Kāinga Ora has two key roles: • Being a world-class public housing landlord; and • partnering with the development community, Māori, local and central government, and others on urban development projects of all sizes.

Kāinga Ora has been set-up to enable a more cohesive, joined-up approach to delivering the Government’s priorities for housing and urban development in New Zealand. These priorities include addressing homelessness and making homes more affordable for New Zealanders.

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DECORATIVE PROJECTS REALISED THROUGH GRC THE ARTISTIC VISION FOR TWO RECENTLY COMPLETED SCULPTURES IN AUCKLAND WAS REALISED THROUGH THE UNIQUE PROPERTIES OF GLASS FIBRE REINFORCED CONCRETE (GRC).

THE MATERIAL’S DURABILITY, LIGHT WEIGHT AND ABILITY TO PRESENT INTRICATE DETAIL HAS COME TO THE FORE IN THE WOMEN’S SUFFRAGE-THEMED ‘SOAPBOX’ IN TAKAPUNA’S KILLARNEY PARK, AS WELL AS AUCKLAND ZOO’S ‘ORANGUTAN NEST’ AND ‘FIG POD’ PUZZLES. The interactive Fig Pod puzzles are a key part of the immersive experience at Auckland Zoo. Image: GRC New Zealand Ltd.

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The Soapbox offers a platform for all voices. Image. Auckland Council, by Serena Stevenson.

KIRK RICKETTS, PROJECT MANAGER AT JACKSON INDUSTRIES, WHICH PLAYED A PIVOTAL ROLE IN BOTH PROJECTS, RECALLS BEING APPROACHED BY ARCHITECTS JASMAX TO BUILD THE “HIGHLYINTRICATE” MOULDS THAT WOULD FORM THE CONCRETE STRUCTURE OF THE SOAPBOX. “After initial discussions it was clear that site restrictions meant standard concrete could not be used due to weight restrictions on loading and placement, so Jackson Industries proposed the use of GRC instead,” says Kirk.

“The mould making process was very time consuming and consisted of crafting two primary components to form the sculpture’s base and the lid.

“Jackson Industries’ in-house moulding material, Caro-C, was used to create the seven separate pieces required for the two mould components, which were then computer numerical controlmachined to the desired pattern layout.

“The mould components were assembled and transported as two complete parts to GRC New Zealand’s Henderson facility to manufacture the final sculptural elements.”

Kirk says Soapbox, which recognises the work of Kate Sheppard and other suffragettes in achieving women’s right to vote in 1893, a world-first, is

positioned to take in the “stunning” view of Lake Pupuke.

“Michael Ross and the team at concrete colour specialists Peter Fell Ltd produced the rustic red tone of the platform, which acknowledges the neighbouring Pumphouse Theatre and the volcanic origins of the lake,” says Kirk.

Situated in the heart of the northern suburbs’ creative arts hub, Soapbox offers the opportunity for people to interact with the platform in whatever way they are inspired to do so.

GRC New Zealand director Dan Carpenter notes that a “number of iterative loops” were run through to ultimately determine the project’s design and approach.

“One of the key challenges was dealing with the shape of Soapbox and how a steel frame could be incorporated to give the structure the strength and durability required,” he says.

“We knew that using GRC for this project would deliver on the key requirements of providing a

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robust and lightweight platform. The lightweight benefits include reduced costs for transport and installation, along with some key environmental considerations regarding the minimal energy needed to produce the platform in GRC compared to alternative solutions. Another key benefit of using GRC is a reduced maintenance cost over time.

“Initially, the team thought they could solve the problem in one go, by using a single mould and frame, but it became apparent early on that two moulds and associated steel frames would be required.”

Praising the quality of the mould provided by Jackson Industries, Dan says his team ran through a series of “dry runs” to ensure it was possible to complete the spraying in one go as well as later perform demoulding “without a hitch”.

“There were a number of tests we completed, which included the form liner release agent, the oxide mix to achieve the required colour, ensuring we could get the consistent thickness needed across the mould, and dry fitting the frame to ensure we could easily complete the end-to-end GRC production activity.

“We also went through meticulous planning and walk throughs for the day of production to ensure there would be no hiccups. I’m glad to say that everything went smoothly.

“One of those unknowns with GRC is the demoulding activity, and we were somewhat nervous even with the level of planning and testing we did. However, to great relief across the team, it was surprisingly straight forward to demould and the sculpture looked amazing.

“The last step was to assemble the sculpture on site at GRC New Zealand’s facility to ensure it was a perfect fit, which it was. This meant transportation and installation went without incident.”

Soapbox was designed by a team of architects and designers including Olivia Collinson, Vanessa Coxhead, Stephanie Darlington, Prue Fea, Jayne Kersten and Madeleine Racz, in collaboration with Jasmax. They were commissioned by Auckland Council to create the sculpture in celebration of the 125th anniversary of women’s suffrage in Aotearoa/New Zealand.

The sculpture was designed to be enjoyed and to be used; to be observed, stood on or sat upon by the public. For more information visit www.aucklandpublicart.com.

Image. Auckland Council, by Serena Stevenson.

Image: GRC New Zealand Ltd.

Image: GRC New Zealand Ltd.

Image. Auckland Council, by Serena Stevenson.

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Image: Auckland Zoo

WHEN DISCUSSING THE AUCKLAND ZOO’S SOUTH EAST ASIA JUNGLE TRACK PROJECT, KIRK RICKETTS FROM JACKSON INDUSTRIES POINTS OUT THAT THE JOB DEMANDED INTENSIVE SURFACE DETAILING. “From a mould-fabrication perspective, the detail of each piece required several days of fine machining due to the intricacy of the designs,” says Kirk.

“Flexible mould material was vital to achieve a high spec result and safe demoulding of the completed parts.”

Jon Parlby, senior designer at Formworks Ltd, which provided the project’s sculptural elements, describes a collaborative venture involving Auckland Zoo, architects Studio Hanson Roberts, Jackson Industries and GRC New Zealand.

“The design brief was challenging,” says Jon. “It required ornate sculptural elements that needed

to be interactive, extremely durable and in keeping with the architects’ vision for the zoo.

“As designers we wanted to push the boundaries of the material capabilities yet maintain an authentic and durable product.

“The expertise and willingness to explore material opportunities of both manufacturing parties enabled us to design and deliver a truly unique set of objects that will stand in place for years to come.”

Jon highlights the in-house machinery capabilities of Jackson Industries as being “extraordinary”.

“Their engagement with us enabled smooth development and subsequent delivery. For Jackson

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Industries, the design detail was shallow but extremely intense, which posed some challenges.

“Due to the elaborate perimeter shapes and intricacy level, rubber moulds were required.

The seat in particular required a complex methodology and material skill level to achieve the mould at a thin enough layer to make demoulding achievable.”

Dan Carpenter highlights the sense of excitement felt around the GRC New Zealand facility when the rubber moulds for the special project were delivered.

“The Jacksons Industries moulds were an absolute work of art, and the team at GRC New Zealand stepped up to the task of ensuring they delivered some beautiful GRC pieces to match.

“The Peter Fell colours specified for the project were very different to what we had used previously, and so several test panels were completed to ensure we could produce the final look that the project required.

“When it came to the day of spraying the moulds, great care was taken to ensure everything was

Auckland Zoo’s Primate team leader, Amy Robbins in the orangutan nest.

Image: Auckland Zoo

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right. Although each piece was quite small, we really took our time to ensure the end product was perfect.

“The quality of the moulds made the demoulding activity straight forward, and for multiple GRC pieces to be cast using the same mould without it degrading.

“The next phase required collaboration with the steel fabricators to connect the intricate GRC pieces to the frames that housed them. With no room for error, the installation was seamless - ultimately bringing the project to life,” says Dan proudly.

As part of the South East Asia Jungle Track visitor experience, the Orangutan Nest and interactive Fig Pod puzzles showcase how the properties of GRC can, in the hands of a dedicated and expert project team, help bring to life an intricate artistic vision as a durable hard-wearing object.

NEW FROM MAX® – THE RB611T TWINTIER™ REBAR TYING TOOL The MAX® TwinTier™ RB611T is reportedly the first battery powered tool in its class with the ability to tie D29 x D32 rebar. TwinTier™ technology’s special attributes include faster tying speed, which further increases productivity; reduced wire consumption, increasing cost savings; and, for end-users, a wire tie that is shorter in height, requiring less concrete to fully cover it.

The MAX® TwinTier™ simultaneously shoots two x 1.0 mm wires around rebar intersections, wrapping once to form a tie equivalent to the strength of a hand snap tie. The TwinTier™ uses TW1061T series tie wire, available in black, poly coated, and stainless steel options. The tool’s 4.0 Ah lithium ion battery will complete approximately

4,000 ties before needing to be recharged.

The MAX® TwinTier™ RB611T’s large jaw allows users to tie D16 x D16 up to D29 x D32 rebar (varying by manufacturer). Its enclosed design offers greater protection against debris and moisture entering the tool. Like other MAX® rebar tying tools, the simple operation of the MAX® TwinTier™ helps reduce muscular skeletal injuries when compared to manual alternatives - a position supported by NIOSH in USA. Overall, no matter the application, the MAX® TwinTier™ reduces the time it takes to complete a job, saves businesses money by cutting man hours needed for each project and increases the productivity of its workers.

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Non-recyclable, landfill-bound plastic waste can now be converted into a hybrid material that improves the properties of concrete.

NEW ZEALAND EYES RESIN8™ AS A CONCRETE SOLUTION TO PLASTIC WASTE AS THE DRIVE TO SECURE A CLEANER AND MORE SUSTAINABLE FUTURE ACCELERATES, SEVERAL COMPANIES IN NEW ZEALAND HAVE BEEN INTRIGUED BY RESIN8™.

This globally patented product is founded on an innovative new technology that converts nonrecyclable, landfill-bound plastic waste into a hybrid mineral-polymer material which actually improves the structural and environmental properties of concrete products.

“RESIN8™ is a working example of the Circular Economy with the potential to scale globally,” says Donald Thomson, the Founder and Chairman of CRDC (The Center for Regenerative Design and Collaboration). “We are successfully transitioning the plastic waste stream into an appreciating value stream for the concrete, construction, and housing industries. We take a zero-waste approach to resource management, which fosters a co-existence with our natural environment and provides measurable societal and financial yields.”

Founded in Costa Rica, CRDC developed RESIN8™ in conjunction with Pedregal, one of Central America’s largest concrete product and construction players. After 18 months of proofof-concept testing with Pedregal, Habitat for Humanity became the first builder in the world to use concrete masonry units made with RESIN8™ in the construction of their low-income housing.

Since then, they have used RESIN8™ blocks in more than 500 homes.

RESIN8™ is made by extruding the mixed plastics (All types 1-7) with Ca(OH)2 and waste ash pozzolans, and then granulating the bulk material into the size, shape and gradation required by 36 concrete

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standard concrete mix designs. The addition of these non-plastic minerals is called “dry cleaning” according to the patent claim filed by CRDC, as no water is required. The dirty plastic is shredded and coated with the Ca(OH)2 and ash, which act as both a desiccant and a disinfectant, thereby making the preconditioned plastic waste pathogen free, odour free and no longer hazardous for handling or transportation.

The preconditioned waste plastic becomes a valuable feed-stock for the direct conversion into a synthetic resin concrete modifier. During a secondary heat extrusion phase, the pretreated resin–mineral melts, mixes and becomes a completely sanitized, inert construction material. The rough surface of the resulting RESIN8™, combined with exposed Ca(OH)2 and pozzolan ash particles, create improved adhesion (both mechanical and chemical) for the important cement aggregate bond. It is virtually indistinguishable in appearance from natural sand aggregate.

Following their successful launch in Costa Rica, CRDC expanded its reach into the U.S. market.

With a small-scale RESIN8™ production facility in New Jersey, CRDC partnered with Fizzano Brothers Concrete Products in Philadelphia and began testing with the National Concrete Masonry Association (NCMA).

CRDC is in the process of developing its first commercial-scale production facility in the U.S.,

but that didn’t stop one multi-national brand from becoming an enthusiastic advocate. “We are proud to be the first to use RESIN8™ block in North America,” said Braskem America CEO Mark Nikolich.

A similar story has unfolded in South Africa, where CRDC has set up a third small-scale RESIN8™ production facility in order to test the market and develop partnerships there.

Test results on blocks made with RESIN8™ meet or exceed ASTM standards for compression strength, water absorption (less), and fire resistance. Loose RESIN8™ material has an R-value 2.8x higher than the sand aggregate that it replaces and 5 percent RESIN8™ concrete block mix has an R-value 25 percent higher than standard block mix. As such, the substitution of natural sand with RESIN8™ provides better thermal resistance and insulation properties, which in turn translates into improved energy efficiency and reduced long term operational energy.

A reduction in ongoing operational energy is important to climate mitigation and emission reduction as energy loads are reduced in comparison to standard concrete elements utilizing natural aggregate. This cumulative ongoing energy reduction is unique to insulation products and is known as the Greenhouse Warming Payback Period. Therefore, concrete

structures utilizing RESIN8™ will eventually outperform the embedded energy natural to sand and will eventually become Net-Zero.

Over the past two years CRDC has diverted more than 750 tonnes of plastic waste from landfill and incineration (approximately 1 tonne per day). For each tonne diverted from incineration, approximately 460 kg of CO2 emissions is kept from entering the atmosphere. This positive impact is just the beginning with several commercial-scale RESIN8™ plants planned for Q4 2021. Each will have a capacity of 3-5 tonnes per hour.

Expansion of this promising new technology into New Zealand is imminent as CRDC is in talks with waste management and concrete manufacturing companies here. This will allow CRDC to formally introduce RESIN8™ to the New Zealand market while producing material from the local waste streams for testing and certification. “’Collaboration’ is in our name”, says Donald Thomson, “we’re looking for strong strategic partnerships to help us scale quickly and effectively. Plastic use is still increasing every year. Now that we have a zero-waste solution to our unmanaged plastic waste problem in the world, we have a massive responsibility – and opportunity - to make it happen at scale.”

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CONCRETE NZ LIBRARY LISTED BELOW IS A SELECTION OF RECENTLY ACQUIRED MATERIAL BY THE CONCRETE NZ LIBRARY. MEMBERS CAN EMAIL LIBRARY@CONCRETENZ.ORG.NZ TO BORROW. CONCRETE HOUSES BY JOE ROLLO Concrete Houses explores the sculptural possibilities of concrete as the material of choice in landmark contemporary houses across the world, as envisioned by major international architects including Sou Fujimoto, Tom Kundig, Valerio Olgiati and Marcio Kogan, and Australians such as Peter Stutchbury, Alex Popov, Ian McDougall and Neil Durbach.

Illustrated throughout with exceptional colour photography, and selected plans and drawings, Concrete Houses celebrates the incontrovertible fusion of concrete’s versatility and brute force to make timeless architecture of lyric beauty.

PRACTICAL CONCRETE MIX DESIGN BY AVIJIT CHAUBEY Practical Concrete Mix Design has been compiled to help readers understand concrete mix design methodology, including formulas and tables involved in the pertinent steps.

This book assists engineers to understand mix design procedures by illuminating every possible explanation for each step, as well as offering practical guidance on tailor-making concrete to meet specific requirements.

The author shows effective methods for optimizing concrete and simultaneously achieving the desired properties of concrete. It covers why, how, and when with respect to concrete proportioning and optimisation.

DURABILITY OF CONCRETE STRUCTURES BY J.M.P.Q. DELGADO (EDITOR) This book provides a collection of recent research works, related to structural stability and durability, service life, reinforced concrete structures, recycled materials, and sustainability with endogenic materials.

Intended as an overview of the current state of knowledge, the book will benefit scientists, students, practitioners, lecturers and other interested parties.

At the same time, the topics covered are relevant to a variety of scientific and engineering disciplines, including civil, materials and mechanical engineering.

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CONTACTS

Concrete NZ Readymix Sector Group Ph (04) 499 0041 Convenor: Rob Gaimster Chair: Richard Sands

Concrete NZ Masonry Sector Group Ph (04) 499 8820 Chair: Dene Cook

FLYING PANELS: HOW CONCRETE PANELS CHANGED THE WORLD BY PEDRO IGNACIO ALONSO AND HUGO PALMAROLA Can concrete panels fly? Though at first it sounds improbable, the answer to this question is “Yes”, and they did so around the world, supported by other structures, both physical and mental. During the second half of the twentieth century, concrete panels were seen soaring across the skies. The book tells the story of concrete panels at the centre of debates in modernizing and industrializing architecture. When manual labour moved to automated mass-production, new concrete element techniques rapidly spread, producing billions of square meters of housing across the globe.

Concrete NZ Precast Sector Group Ph (04) 499 8820 Convenor: Dave McGuigan Chair: John Marshall

Concrete NZ Learned Society Ph (09) 536 5410 Convenor: Adam Leach Events Manager: Allan Bluett President: Dr Nicholas Brooke

LIBRARY QUIZ To go in the draw to win a copy of Flying Panels: How Concrete Panels Changed the World by Pedro Ignacio Alonso and Hugo Palmarola answer the following question: When did New Zealand establish universal suffrage / extend the right to vote to women?

Email your answer to library@concretenz.org.nz. Entries close Friday 21 May 2021.

Concrete NZ Reinforcing Stakeholder Group Ph (04) 499 8820 Convenor: Dave McGuigan Chair: Rakesh Nauhria

Congratulations to Peter McDermott of Allied Concrete, who correctly answered the Vol. 61 Iss. 01 Library Quiz to receive a copy of California Concrete: A Landscape of Skateparks by Amir Zaki and Tony Hawk.

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