concrete VOLUME 56 ISSUE 2
readinG concrete can contribute to your skills maintenance
525 Golden Gate THE NEXT GENERATION OF CONCRETE BUILDINGS
Apartments of the Future ccanz vision for meDium density living in christchurch
Concrete for the Community MORE EXAMPLES OF outstanding facilities for greatEr wellbeing
THE MAGAZINE OF THE CEMENT AND CONCRETE ASSOCIATION OF NEW ZEALAND
UPFRONT
concrete MAGAZINE
In late November 2012 Cabinet approved New Zealand Transport Agency’s (NZTA) application to pursue a Public-Private Partnership (PPP) for Transmission Gully – the much anticipated 27-km leg of the 110-km Wellington Northern Corridor.
Editor/Advertising: Adam Leach +64 4 915 0383 adam@ccanz.org.nz
PPP’s are a long-term contract between the public and private sectors covering the financing, design, building, maintenance and operation of public infrastructure or services.
Subscriptions: Kylie Henderson +64 4 499 8820
They are increasingly commonplace in large construction projects overseas and are seen as a way to use private sector innovation and funding sources, as well as increase certainty of delivery by transferring risk to the private sector.
admin@ccanz.org.nz
The NZTA predict that a PPP for Transmission Gully will drive greater value for money in dealing with the project’s size and complexity, as well as allowing for construction to begin in 2014, with an anticipated completion date of 2020.
Association of New Zealand)
Since the NZTA announced its intention to proceed with a PPP it has received strong support from those who see it as more effective than traditional procurement methods. Similarly, CCANZ believes the PPP is an opportunity for innovation, and to build a new era of roads made from concrete. The economic, environmental and safety benefits of concrete roads are well documented. Concrete’s long-term durability offers significant potential returns on investment. A concrete road’s extended service life, low maintenance, and reduced fuel consumption benefits for motorists are compelling economic factors. Concrete roads can also be good for the environment. They require minimal maintenance, which in turn reduces congestion and exhaust emissions. They also enhance the fuel efficiency of heavy vehicles by reducing rolling resistance. Concrete roads could also slow the process of global warming. The albedo of concrete - the ratio of the reflected solar energy to the total solar energy received – is high. This means the light coloured surface of a concrete road translates to greater radiation reflectivity. The light coloured surface of concrete roads can also enhance roadway lighting systems, improving safety for motorists. Noise factors can also be mitigated. Grind-and-groove surface technology to reduce surface noise from concrete roads is now commonplace in Australia and North America. While these benefits are generally recognised, New Zealand has been slow to take advantage of them. NZTA’s high discount rate is a factor in this. This rate determines the cost and benefits of infrastructure projects over time, and relates to the evaluation period for infrastructure. Although both have been adjusted recently, from a discount rate of 10% to 8% and an evaluation period of 25 years to 30-years, a lower discount rate and longer evaluation period would most likely favour infrastructure projects that reduce the total cost of maintenance and operation overtime–such as projects with a long service-life achieved through concrete.
concrete is published quarterly by CCANZ (Cement & Concrete
PO Box 448 Level 6, 142 Featherston St Wellington NEW ZEALAND Tel: +64 4 499 8820 Fax: +64 4 499 7760. Email: admin@ccanz.org.nz Website: www.ccanz.org.nz ISSN: 1174-8540 ISSN: 1179-9374 (online) Disclaimer: The views expressed in concrete are not necessarily those of the Cement & Concrete Association of New Zealand. 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 2013 CCANZ (Cement & Concrete Association of New Zealand)
It must also be considered that global oil prices are trending upwards, meaning that traditional road technologies are becoming more and more costly to install and maintain. The NZTA has a good reputation for prudent asset management. This could be enhanced further with the selection of concrete as the roading material of choice, particularly for high traffic density sections of the Roads of National Significance. Rob Gaimster CCANZ, CEO
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Cover photo: San Francisco Public Utilities Commission HQ, 525 Golden Gate Avenue, San Fransciso Image: © San Francisco Public Utilities Commission; Carmen Magana
NEWS
NEWS CCANZ WELCOMES ALISTAIR RUSSELL
Alistair Russell
ROC
KCOTE
Dr Alistair Russell recently joined CCANZ as Manager - Structural Performance & Engineering Systems. Immediately prior to starting with CCANZ Alistair was based in Vancouver, Canada, where he worked as a Structural Engineering Graduate at Ausenco Sandwell.
During 2010 Alistair was a Post-doctoral Fellow at the University of British Columbia where he was involved in preparing a critical review of unreinforced masonry assessment guidelines. Before leaving New Zealand, Alistair was a Lecturer in Civil and Environmental Engineering at the University of Auckland and taught concrete related courses. Alistair was awarded his PhD in Structural Engineering from the University of Auckland in 2010, the focus of which was the characterisation and seismic assessment of unreinforced masonry buildings. In his new role at CCANZ Alistair will endeavour to provide effective technical management on all structural and civil engineering matters.
THE BENDOMETER IS BACK CCANZ and the Pacific Steel Group have reissued the Bendometer to assist best practice in the bending of steel reinforcing. The Bendometer is endorsed by building and housing of the Ministry of Business, Innovation and Employment (MBIE). During use the appropriate disc should be selected by matching the width of one of the notches to the diameter of the bar to be checked. The inside diameter of each bend in the bar should be equal to or greater than the diameter of the selected disc. Any bend with an inside diameter less than the diameter of the selected disc, does not comply with New Zealand Standards. Note: The Bendometer is intended for use on main bars only, not for stirrups and ties. The Bendometer is freely available by contacting CCANZ on 04 499 8820 or by emailing admin@ccanz.org.nz
Proven technology. Lightweight AAC masonry flooring systems are a tried and tested method of construction around the world. The Integra Flooring System offers a durable and cost effective solution in both light commerical and residential flooring with many benefits associated with masonry floors; Energy efficiency, thermal mass, sound absorbing qualities and speed of installation to create a solid, lightweight masonry floor. Integra - lightweight concrete systems for all your building projects.
www.reseneconstruction.co.nz 0800 50 70 40
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NEWS
CONCRETE PUMPING HEALTH AND SAFETY GUIDELINES Pumping concrete is an efficient method of moving and placing concrete. This process is used in the manufacture of pre-cast and tilt-up panels, concrete formwork, slab construction, concrete paving and concrete spraying.
Concrete Pumping Health and Safety Guidelines
These guidelines provide practical advice about the safe operation and maintenance of concrete pumping equipment and the environment this equipment is used in.
FEBRUARY 2013
They are based on the current knowledge of construction methods within the industry and were prepared by a committee of representatives from the Concrete Pumping Association of New Zealand (CPANZ) and the Ministry of Business, Innovation and Employment (MBIE) with input from a public consultation process. The guidelines include the following topics: • managing site hazards such as noise, wet cement, manual handling, carbon monoxide and electricity • safe work planning and preparation, including principalcontractor liaison DOL 12274 FEB 13
• concrete pumping equipment set-up • concrete pumping operation • maintenance and inspection The guidelines can be downloaded from the MBIE Labour Information website – www.dol.govt.nz
LEADERS IN CONCRETE TECHNOLOGY
JOINT-FREE FLOOR SLABS
Concrete solutions
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NON-HAZARDOUS PRODUCTS TO SAFELY REPLACE HARSH ACIDS, SOLVENTS, AND CAUSTICS
INTEGRAL WATERPROOFING OF CONCRETE SLABS AND STRUCTURES
Call the sole agent on 07 575 5410 or visit: www.demden.co.nz
products & PRACTICE
The Products and Practice page provides manufacturers, agents and consultants with an alternative option to showcase the features and benefits of their goods and services. Visit the CCANZ website (www.ccanz.org.nz) to download the magazine ratecard, and discover how to take advantage of the cost competitive opportunities offered through advertising in Concrete.
DRAMIX STEEL FIBRES - CREATING NEW LEVELS OF CONCRETE REINFORCEMENT With the brand new range of Dramix, steel fibre reinforcement is being taken to a whole new level. An updated and expanded range The existing range of Dramix steel fibres has been rebranded as the 3D series. It remains widely recognized as the best solution currently on the market when it comes to performance and cost-efficiency. However, the introduction of two brand new fibre series in the Dramix range opens up a world of possibilities to create with concrete. Unique shapes, unique capabilities The unique shape of the new Dramix 5D and 4D fibres offer previously unavailable levels of anchorage, tensile strength and ductility, guaranteeing maximum performance. At the same time, they enable the building industry to use steel fibre reinforcement in a wide range of new applications. Dramix 5D – previously unseen levels of performance The Dramix 5D series provides you with the ultimate in performance, thanks to a unique combination of a perfectly shaped hook, ductile and high tensile strength wire. The improved hook of the 5D fibres is non-deformable, providing perfect anchorage. The ductile wire of the 5D series elongates while the hook remains firmly in place, enhancing both the strength and the ductility of the concrete. The 5D is the perfect solution for strength requirements in structural applications either on its own or in combination with conventional reinforcing, including: Foundation slabs, rafts, pile supported slabs, pad foundations and some suspended structures. Dramix 4D – designed with serviceability in mind The Dramix 4D series is designed with optimal serviceability in mind. Tensile strength and anchorage are engineered specifically to affect cracks between 0.1 and 0.3 mm, enabling you to create durable and liquid-tight structures. At the same time, the 4D series is also the ideal solution for applications where steel fibres are combined with conventional reinforcement. Typical 4D applications include: Joint free floors (Seamless floors), restrained slabs, liquid tight slabs/structures, CRCP motorways, and harbour pavements.
Dramix 3D – often imitated, never equalled Dramix 3D is the new name for the existing range of Dramix steel fibres, which throughout the years has become the reference in steel fibre reinforcement. Combining high performance, durability and ease-of-use, 3D provides you with a time-saving and cost-efficient alternative to traditional concrete reinforcement solutions: Jointed floors, jointed yard slabs, shotcrete and precast.
For further information call 0800 665 755 or visit www.bosfa.com – The leader in fibre reinforced concrete solutions.
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concrete 5
Concrete truck
photo competition
The New Zealand Ready Mixed Concrete Association (NZRMCA) recently held a competition amongst its memberS to see who could supply the most impressive photograph of a concrete truck in a spectacular and/or challenging environment. Amongst numerous entries Higgins Concrete and Allied Concrete supplied outstanding examples that captured just how challenging the delivery of ready mixed concrete can be, and just how committed NZRMCA members are to exceeding the customer’s expectationS – literally going the extra distance.
WINNER
HIGHLY COMMENDED
HIGGINS CONCRETE – WELLINGTON HARBOUR
ALLIED CONCRETE – MOUNT HUTT
In May 2012 Higgins Concrete Wellington supplied 18m³ of concrete to Utility Construction for a wind turbine foundation located on Somes/Matiu Island in Wellington Harbour. On a picture perfect day, four 4.5m³ concrete trucks, loaded at Higgins’ Glover Street plant, boarded the barge at Eastbourne. Upon arrival at Somes/Matiu Island, the trucks travelled up from the beach to the island’s highest point, discharged into the foundation block, then made their way back down to the barge. The job complete - all trucks were delivered home safe and sound, much to the relief of Higgins Manager, Scott Ferguson.
In 2006 Allied Concrete supplied 600m3 of concrete for the pylons of the Summit Six Chair Lift on Mt Hutt (2080m above sea level). Due to the steepness of the terrain only 6 wheeled Sterling trucks were used, each carrying a maximum of 3m3 - anymore and the concrete poured out the back. Larger trucks from the Ashburton fleet hauled their loads to the ski area base at 1620m where the concrete was transferred to the shuttle trucks. The Sterling trucks’ low down torque helped attack the 460m climb, which took 40 minutes to negotiate and included several three point turns.
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W IN N
ER
CO H M IG M H EN LY D ED
Image: HELiPRO
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GUIDING HOUSE REPAIRS AND REBUILDS GUIDANCE FOR REBUILDING AND REPAIRING HOUSES IN THE CANTERBURY GREEN ZONE HAS BEEN UPDATED AND BROUGHT TOGETHER IN ONE FOLDER, MAKING IT EASIER TO USE. Published by the Ministry of Business, Innovation & Employment (MBIE), the guidance will assist in the repair and rebuild of homes affected by the earthquakes in flat areas of the Canterbury green zone. In 2011 flat areas of the green zone were divided into three foundation technical categories – TC1, TC2 and TC3. These were developed as a guide to the level of site investigation required and the appropriate foundations for new and rebuilt homes. GUIDELINES IN ONE DOCUMENT The new document brings together Revised guidance on repairing and rebuilding houses affected by the Canterbury earthquake sequence, published in November 2011, Appendix C, published in May 2012, which focuses on repairs and rebuilds in technical category 3, and Guidelines for subdivisions, released in September 2012. The technical changes, which are not major, are clearly marked. It is structured in four parts designed to be filed together in one folder. The November 2011 guidance, which focuses on TC1 and TC2, is now Part A and Part B, the TC3 guidance is Part C, and the subdivision guidelines are Part D. EASILY UPDATABLE Research into the impacts of the Canterbury earthquakes is ongoing, and new foundation options are being investigated and developed in partnership with the sector. The new format can be updated to include additional information as released. The updated guidance emphasises that foundation technical categories are only the starting point for assessing sites that may be prone to liquefaction in major earthquakes. Engineering advice is generally required to decide the appropriate foundations. The engineer may advise deep geotechnical investigations of a site where foundation rebuilds are needed or may decide to use areawide data.
If the slope of the floor between two points more than 2 m apart is more than 0.5% and the variation in level over the floor plan is more than 50 mm, the floor or foundation probably needs to be relevelled or possibly rebuilt depending on the degree of tilt. Cracks in ceramic floor tiles and distress in vinyl floor coverings and carpet are other indicators, particularly in framed houses on concrete floors. Even if these indicative limits are not exceeded, floor and superstructure repairs may be required. There is new information on how timber and concrete piles should be packed to relevel floors.
CRACKS IN SLAB AND FOUNDATION WALLS
FOUNDATION OPTIONS AND REPAIRS
The updated guidance makes it clear that some cracks in concrete slabs and foundation walls can be repaired without input from a professional engineer.
The updated guidance specifies that all new slab-on-grade floors must be reinforced with grade 500E mesh or equivalent reinforcing steel and tied to the edge foundation. This reflects Acceptable Solution B1/AS1.
Cracks can be caused by factors other than earthquakes, for example, shrinkage or foundation settlement over time. The guidance advocates that any cracks caused or exacerbated by earthquakes should be repaired – it distinguishes between cracks requiring structural repair and cracks that can be repaired quite simply. It also includes updated advice on sealing cracks in perimeter foundation walls. TO RELEVEL OR REBUILD FOUNDATIONS? The guidance clarifies indicator criteria for deciding if a foundation needs to be relevelled or rebuilt. The criteria have been extended to include advice on partial rebuilds. Relevels or rebuilds are triggered by excessive differential settlements or floor stretches.
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There are minor updates to foundation options. Ground improvement options are available in a wider range of circumstances. New information and updated details have been provided for deep pile options. Clarity is provided on the use of options where there is low soil-bearing capacity. The updated guidance also covers repairs to bracing, linings and chimneys, as well as guidelines for subdivisions. Download the full updated guidance document from www.dbh. govt.nz/guidance-on-repairs-after-earthquake A series of Canterbury rebuild information sheets are also available from www.dbh.govt.nz/canterbury-rebuild-info-sheets
FIRTH’S WORLD-LEADING FLOORING SYSTEM RECEIVES PRAISE FROM MINISTER FIRTH’S REVISIONARY FLOORING SYSTEM RIBRAFT® TC3, WHICH ALLOWS FOR CONSTRUCTION TO SIT ON THE GROUND NOT IN IT, WAS UNVEILED RECENTLY IN CHRISTCHURCH BY CANTERBURY EARTHQUAKE RECOVERY MINISTER GERRY BROWNLEE. Mr Brownlee spoke at the pouring of a new concrete foundation solution on a TC3 property in the Christchurch suburb of Hoon Hay with TV crews from TV3, TVNZ, CTV and Mainland TV present. He thanked all those that had worked so hard to create viable options to speed up the delivery of solutions for Christchurch residents. There are around 28,000 properties in TC3 areas. Around 12,500 of these homes have major foundation and pile damage requiring further investigation of the ground around them. Engineers must look at TC3 land in more detail when deciding what foundations are required so the property will perform well and be safe in future earthquakes. “After eight months in development we have now created a viable, cost effective TC3 foundation option which will help give home owners and builders more peace of mind,” says Andrew Moss, General Manager of Firth. RibRaft TC3 comprises of upper and lower slabs that can be jacked apart following an earthquake that causes settlement, allowing the house to be re-levelled quickly and easily with reoccupation inside four weeks. It is seismically strong, energy efficient and cost effective due to reduced time and labour required. It is also less disruptive on the land as it lessens excavation. ®
“There’s been extraordinary demand for the Ribraft® EQ (TC2) version which now accounts for a third of all new building foundations in Christchurch. We now expect strong demand for RibRaft® TC3 which may well be the answer to the prayers of many,” adds Moss.
Andrew Moss, General Manager for Firth and Jon Hambling, Technical Manager at the unveiling
WHAT EXACTLY IS TC3? Technical Categories (TC1, 2 and 3) are a classification developed by the former Department of Building & Housing (DBH) to describe how the land is expected to perform in future earthquakes. They are part of the guidance provided by DBH regarding engineering options for new or repaired residential foundations in Canterbury. See the Canterbury Earthquake Recovery Authority website (www.cera.govt.nz) for detailed information about technical categories and what they mean.
INDUSTRIAL FLOOR DESIGN Join the next Maccaferri workshop to enhance your skills designing Wirand® steel fibre reinforced floor slabs.
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Learn to use Maccaferri’s PAVE software – an effective tool to design industrial floors. To attend our workshops or find out more about PAVE software call
0800 60 60 20
www.maccaferri.co.nz | sales@maccaferri.co.nz
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THE CCANZ VISION FOR A NEW URBAN VILLAGE The finalists of Breathe (New Urban Village), an international competition to design and build a medium density apartment complex for Christchurch, were announced in late February by Building and Construction Minister Maurice Williamson. Four designs - two from New Zealand, one from Australia and an Italian group – were selected by the judges from a total of 58 entries from around the world.
To further support the competition’s vision of offering Christchurch residents exceptional quality of life, CCANZ developed its own preliminary design – see adjacent.
• Walker Architecture and Design and Ceres NZ
Although the CCANZ entry did not feature amongst the shortlist it is being used as the basis for The Apartment Design Guide. This CCANZ publication will offer general advice to those wishing to undertake new building development.
• Jasmax, Viva Project, Evergreen Realty and Latitude Group • Ganellen, the University of Technology Sydney and Design King Company Architects • Anselmi Attiani Associated Architects, Cresco Group and Holloway Builders The finalists have three months (and $20,000) to take their initial concepts through to a more developed design. The winning concept, to be announced in August, will be built adjacent to Latimer Square. CCANZ identified the competition as an ideal opportunity to promote the advantages of residential concrete construction, choosing to become a sponsor along with EECA and BRANZ.
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The flexible framework provided by the Guide will also help designers and developers understand the benefits that can be achieved through concrete construction, while also providing insights into optimum urban planning. For further information on the CCANZ Apartment Design Guide contact CCANZ architect (EU) Ralf Kessel on 04 499 8820 or ralf@ccanz.org.nz For more information on the Breathe (New Urban Village) competition visit www.futurechristchurch.co.nz/breathe
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525 GOLDEN GATE PUSHING STRUCTURAL AND MATERIAL BOUNDARIES WITH CONCRETE
Image: © San Francisco Public Utilities Commission; Katherine Du Tiel-Photographer
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Sub-floor of one of the building’s two shear concrete cores.
BY COMBINING LOW DAMAGE STRUCTURAL DESIGN TECHNOLOGIES WITH A RIGOROUS RE-INTERPRETATION OF CONCRETE MIXED DESIGN, ALONG WITH A HOST OF OTHER ‘GREEN’ FEATURES, 525 GOLDEN GATE AVENUE IN SAN FRANCISCO HAS SET THE CURRENT BENCHMARK IN SUSTAINABLE BUILDINGS. Opened in 2012, the new US$190 million headquarters of the San Francisco Public Utilities Commission (PUC) houses over 900 employees within its 13-storeys / 25,781m2 office space. Designed by KMD Architects & Stevens Architects the structure embodies a commitment to sustainability in office building design that aligns seamlessly the PUC’s undertakings as San Francisco’s energy and water services provider. The accomplishments of 525 Golden Gate, in comparison to similarsized office buildings, are succinctly expressed in three metrics:
internal accelerations, all while retaining the same column grid and core locations from the original steel frame design. The concrete frame also allowed for a reduction in the floor-tofloor height by approximately 300mm, creating enough space within the existing building envelope for an extra storey. Another benefit of a concrete frame was that once the client had accepted an exposed concrete aesthetic, the need for US$10 million worth of fireproofing and finishes (e.g. suspended ceiling) was eliminated.
• 50% reduced carbon footprint • 32% less energy consumed • 60% less water consumed The innovative use of concrete has been key to elevating 525 Golden Gate to the position of the ‘greenest’ office building in North America. CONCRETE FRAME Within the context of a seismically active region, and despite the US Green Building Council’s LEED rating system offering no credits for seismic design, the premium placed on a resilient frame was a major part of the designers’ thinking in terms of sustainable construction. Structural engineers Tipping Mar Associates, in partnership with main contractor Webcor, adopted a self-centering (aka “selfhealing”) structural frame that makes use of post-tensioned cables within in-situ concrete elements, most notably the building’s two vertically tensioned concrete cores. During a significant seismic event the system allows the building to rock, with the tensioned cable, unbonded in ducts running through structural components (slabs and shear walls), restoring the frame to its original position once shaking has finished. Initially conceived as a steel frame building, by switching to concrete the designers were able to enhance performance during an “extreme” earthquake, particularly in terms of handling higher Images: © San Francisco Public Utilities Commission; Carmen Magana volume 56 issue 2
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concrete 13
While the frame’s exposed finish contributed to the building’s energy efficiency in terms of passive solar design, its minimum reflectivity had to be clearly specified so as to be compatible with the building’s illumination strategy that automatically dims fixtures when daylight levels are sufficient. CONCRETE MIX DESIGN While working on the design of the concrete structure, the project team also strove to reduce the embodied energy of the concrete itself. To minimize its carbon footprint, about 70% of the Portland cement in a standard concrete mix was substituted with supplementary cementitious materials (SCMs), including slag (a byproduct of steelmaking) and fly ash (a byproduct of coal-fired power plants).
hydration, in particular strength gain, are slowed. This was crucial, as it has a huge impact on the quality of the finished product and the construction schedule. To help determine when formwork could be stripped and when post-tensioning could be applied, Webcor and its subcontractor, Central Concrete Supply, used maturity testing. This method involves monitoring the heat generated as a result of hydration, and then correlating the results to laboratory tests for the same mix. Relying on this test method, formwork was removed from the columns about 24 hours after concrete placement, and the horizontal tendons tensioned around three days after each slab pour. ENERGY EFFICIENCY
By replacing a material that is relatively energy-intensive to manufacture with waste products that might otherwise have be sent to landfills, carbon emissions from the production of the concrete were halved.
A wind turbine tower on the north façade, solar panels on sunny exteriors, sun-shading and other techniques combine to make the building one of the most power-efficient anywhere, using 32% less energy than similar sized buildings.
The unusual mix however, was not without its challenges. The structure called for much higher levels of SCMs than is the norm, creating difficulties around understanding how the dynamics of
A state-of-the-art raised flooring system incorporates the building’s data and ventilation infrastructure and reduces heating, cooling and ventilation energy costs by around 51%.
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WATER CONSERVATION At the heart of the PUC building’s water saving features is the Worrell Water Technologies “Living Machine”, a cutting-edge grey and black-water management system. The Living Machine, along with faucet sensors and on-demand water heaters help reduce the daily water consumption from 45 to 19 litres per occupant. Stormwater is also collected and treated for use in on-site irrigation. ADVANCING THE CONCEPT OF SUSTAINABLE DESIGN Described by its designers as the “poster-child” for environmentally sustainable office buildings, the PUC building clearly articulates its owner’s resource management objectives, while at the same time providing a sleek, modern architectural statement that enhances its urban surroundings. However, it is the building’s assimilation of resilient low damage design (using concrete systems) with the more conventional metrics of sustainability, such as resource conservation, that underpins its true significance for office buildings in seismically prone regions.
Concrete Solutions Our Rockcote MultiStop range of premium construction mortars are designed for ease of use as sandable or non sandable patch, repair, & finishing plasters to achieve the best result over masonry substrates.
sources Gonchar, J. (2011). Green at its core. McGraw-Hill construction: Continuing education. Retrieved from http://continuingeducation.construction.com Henderson, Nam. (2012). 525 Golden Gate seismically and systematically sustainable. Architect features. Retrieved from http://www.archinect.com
www.reseneconstruction.co.nz 0800 50 70 40
KMD Architects. (2012). San Francisco Public Utilities Commission headquarters designed by KMD Architects & Stevens Associates opens as poster-child for innovation in energy, water conservation. Media release. Retrieved from http://www.kmdarchitects.com
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CONCRETE CRACK
INJECTION WORTH DOING WORTH DOING RIGHT FOLLOWING THE CANTERBURY EARTHQUAKES MANY OWNERS OF CONCRETE STRUCTURES HAVE OR ARE UNDERTAKING PROGRAMMES OF REMEDIATION. WITH RESILIENCE A KEY OBJECTIVE IN REBUILD PLANS ACROSS THE REGION, IT
THE CAUSES OF CRACKING Concrete is a metaphor for strength and durability. However, there are many factors which by themselves or in combination, can undermine reinforced concrete’s service life performance. The properties of concrete’s constituent materials (i.e. coarse aggregate, fine aggregate, cement and water) play a substantial role in terms of concrete quality, as does their interaction within the mix design to create properties such as strength and permeability. Similarly, the handling of concrete during placing, compaction and curing can also dramatically influence performance, as can decisions made during design and detailing, such as joint configuration and concrete cover over steel reinforcement. Other factors that can impact on the performance of reinforced concrete are natural and artificial agents in the form of acid attack, bacterial growth, freeze-thaw action and fire damage. Finally, loadings, whether wind, snow, abrasion, vibration or (as in Christchurch’s case) seismic, are also potential causes of compromised concrete performance.
IS IMPORTANT THAT CONCRETE REPAIR, IN
CRACK TYPES AND TREATMENT
PARTICULAR CRACK INJECTION, IS CARRIED OUT TO
There are many different types of cracks, ranging from plastic and constructional through to thermal and structural. In a domestic setting for instance, cracks may appear in new concrete driveways due to early age problems.
THE HIGHEST POSSIBLE STANDARDS.
Of more immediate concern are cracks that appear in existing concrete buildings as a result movement during an earthquake. In this instance, crack classification takes place following a comprehensive inspection as part of a structural integrity survey.
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Core sample showing successful full penetration injection
Assessment techniques can include a visual inspection, along with any number of non-destructive sampling and testing procedures such as lump and core samples, rebound hammer tests, crack width measurement, pull-out tests and ground-penetrating radar (GPR). Once the cracking has been classified, then the appropriate protective / remedial system can be applied, whether it is a patch repair, moisture barrier, steel reinforcement coating, cathodic system or crack repair. Along with classifying the cracking, determining its extent and formulating a repair strategy and method, performing the repair itself requires a significant level of expertise. CANTERBURY REBUILD Christchurch based company Concrete Connect, who have specialised in concrete adhesion, protection and repair services since 2004, predominantly for the commercial and industrial building industry, have experienced high levels of activity over the past few years. George Roberts, director of Concrete Connect, comments that demand for concrete repair has increased as the Canterbury rebuild gathers momentum, “We are definitely seeing property owners, their insurance company and technical consultants, placing a greater emphasis on concrete repair.” George is quick to point out however, that the entire concrete repair process must be extremely thorough, accounting for technical and economic considerations, as well as material quality, workmanship, quality assurance and on-going maintenance. “I cannot emphasise enough that training, experience and competency are crucial to a successful outcome,” says George. “Yet there are currently no New Zealand Standards in place in this
Core sample of failed injection
area, and no training or specific qualifications available to indicate a certain level of know-how.” “Due to the poor governance and a lack of Standards, along with the availability of product and equipment to purchase from local hardware stores,” George adds “we are often called into repair failed injection projects, which adds thousands of dollars to the overall repair bill.” As with all procurement decisions in the construction industry, price will inevitably be a major consideration, but it should not be the sole determining factor in choosing a repair specialist. “Property owners need to weigh-up the value they will ultimately receive from their decisions,” says George. “A dollar saved today, may mean additional costs and lead to a structural safety hazard further down the track if the initial repair is sub-standard. Contractors who can demonstrate proven results should definitely be preferred during the selection process.” “Ultimately, a crack injection repair carried out by an experienced specialist should achieve 80-100% penetration, following European Standards. For the owner to gain peace-of-mind that the structural integrity of the building is restored, penetration results should be verified through core testing, followed by a visual and destructive test on the core,” concludes George. RESOURCES HB 84-1996 Guide to Concrete Repair and Protection*. Australian Concrete Repair Association, Standards Australia, CSIRO and Standards New Zealand (1996). HB 84-2006 Guide to Concrete Repair and Protection. Australian Concrete Repair Association, Standards Australia and CSIRO (2006). Information Bulletin 08 Repairs to Concrete. Cement & Concrete Association of New Zealand (2005). * Current in New Zealand
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conc r e t e f o r t h e commun i t y – PA RT 2
CONCRETE FOR THE COMMUNITY IN THE PREVIOUS ISSUE OF CONCRETE WE TOOK A TOUR OF TWO OUTSTANDING PROJECTS THAT ILLUSTRATED HOW THE PROPERTIES OF CONCRETE ARE HELPING TO CREATE SECURE, COMFORTABLE AND VIBRANT FACILITIES THAT ENSURE THE HEALTH AND WELL-BEING OF YOUNG AND OLD ALIKE. OVER THE FOLLOWING PAGES WE FEATURE TWO MORE RECENTLY COMPLETED PROJECTS THAT SHOWCASE THE VERY BEST OF CONCRETE FOR THE COMMUNITY
St Peter’s College Sports Complex ENCIRCLED BY A RAILWAY LINE, MOTORWAY AND BUSY ARTERIAL ROAD ST PETER’S COLLEGE IS EXPOSED TO HIGH LEVELS OF NOISE. CONCRETE OFFERED THE NEW SPORTS COMPLEX AN EFFECTIVE SOLUTION TO THE ACOUSTIC ISSUES OF THE SITE, AS WELL AS PROVIDING A LEVEL OF ROBUSTNESS SUITED FOR A BOYS’ SCHOOL. 18 concrete
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Simon DeVitt Photography
conc r e t e f o r t h e commun i t y – PA RT 2
The only available space for the Complex was the Catholic Netball Courts, separated from the rest of the school by an 11 metre cliff and fronting the noisy road and railway. This however, gave an opportunity for the school to establish an imposing presence on Khyber Pass and contribute to the urban context. Particularly striking is the façade which proclaims the motto “to love & to serve”. In diagrammatic form the Complex simply created a large barrel vaulted roof over the existing playing surface, formed an access way down from the road and established pedestrian connections to the main school from Khyber Pass via a corridor-viewing gallery that bisects the building. There is an accommodation wing on the west side of the corridor, while the remainder of the site has been converted to an artificial training turf and acts as a counterpoint to the mass of the hall. Solid concrete precast walls on concrete columns are used as the flanks of the building and support the lightweight steel roofed vault while providing acoustic protection from the adjacent road. The upper parts are exposed basalt aggregate reflecting the underlying volcanic rock of the site. At street level a stretched tensile steel mesh covered in climbing plants forms a green wall that softens the interaction with the footpath and pedestrians. The accommodation wing is solidly constructed from double skinned concrete masonry to provide acoustic protection from the railway. The vaulted ends are, in contrast, as transparent as possible. At one end they open to the adjacent training field while at the other a glazed wall to the upper level corridor allows a full view of the playing area. The straightforward construction and exposed finishes provide a suitably robust environment. The classrooms and main hall have mechanically assisted ventilation to allow them to operate with the windows closed due to the excessive noise of the road and diesel powered trains, they can also operate in a naturally ventilated mode when conditions allow. Roof and walls are heavily insulated to both reduce energy usage and contribute to the acoustic performance of the building shell. St Peter’s College Sports Complex Client Catholic Diocese of Auckland Consultants Architectus Auckland, Structure Design Contractor Aspec Construction volume 56 issue 2
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Ormiston Activity Centre LOCATED IN THE NEW RESIDENTIAL DEVELOPMENT OF FLAT BUSH IN MANUKAU, THE CONCRETE ELEMENTS OF THE ORMISTON ACTIVITY CENTRE AND SURROUNDING SKATE PARK ENSURE THIS VIBRANT FACILITY, AN INCREASINGLY POPULAR GATHERING POINT FOR THE AREA’S GROWING YOUTH POPULATION, IS ROBUST ENOUGH TO ACCOMMODATE THE ENERGY AND ENTHUSIASIM OF ITS PATRONS. 20 concrete
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In addition to the skate park quadrant, the Centre is an assemblage of four distinct parts – a precast concrete stair tower block, an amenities/viewing platform block, a multi-use meeting room block, and a canopy – each designed with unique shape and material qualities that combine to create the dynamic and durable built form. The precast concrete stair tower block signals an entry point and corner marker assisting with orientation within Barry Curtis Park. It also acts as a spatial reference within the landscape, with vertical lines helping to create a powerful visual presence. An extrovert, the smaller amenities/viewing platform block’s character is defined by colourful steel cladding that signals the building’s playful character. Interest in this block is increased further by the viewing platform, which provides an elevated vantage point to view skate park activities, as well as to be seen from. An enclosed, more introverted block, the multi-use meeting space is clearly contrasted with the vibrant amenities block. Constructed of concrete masonry, the modular surface is animated by sliding shutters to create three operable facades. This allows the requirements of security, privacy, ventilation, lighting and acoustic issues to be balanced. At night, large shutters completely enclose the box to ensure security. Providing an element of shelter against sun and rain, the canopy is a strong horizontal element that helps define the intermediate outdoor space. From a concrete perspective the Centre makes use of the locally produced material’s durable long life properties that reduce ongoing management and maintenance costs. The hard floor finishes act as a heat sink. This deployment of thermal mass, in combination with glazing and insulation, helps to control heat loss in winter and over-heating in summer. Also contributing to the Centre’s passive solar design is its sculptural vertical and horizontal external shades, and manually controlled natural ventilation. Ormiston Activity Centre Client Manukau City Council Consultants Archoffice, Brown & Thomson Contractor Watts & Hughes Construction
Projects featured in Concrete for the Community Part 1 & 2 were entries in the 2012 Concrete3 Sustainability Awards.
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CCANZ Library Listed below is a small selection of recently acquired material by the CCANZ library. email library@ccanz.org.nz TO BORROW. EARTHQUAKE ENGINEERING FOR STRUCTURAL DESIGN BY VICTOR GIONCU AND FEDERICO MAZZOLANI Seismic design is the bringing together of Earthquake Engineering and Engineering Seismology. It focuses on the seismological aspects of design - analysing various types of earthquake and how they affect structures differently. Understanding the distinction between these earthquake types and their impacts on buildings can influence whether a building stands or falls, or how much it costs to repair.
CONCRETE
FUTURES DAMAGE RESISTANT DESIGN USING CONCRETE SYSTEMS
This is an essential guide for professionals working on structures in earthquake zones around the world. SEISMIC DESIGN AIDS FOR NONLINEAR PUSHOVER ANALYSIS OF REINFORCED CONCRETE AND STEEL BRIDGES BY JEFFREY GER AND FRANKLIN CHENG Nonlinear static monotonic (pushover) analysis has become a common practice in performance-based bridge seismic design. Its popularity is due to its ability to identify failure modes and design limit states and to provide the progressive collapse sequence of earthquake damaged structures. This is a complete reference on pushover analysis for practicing engineers, covering pushover analysis of reinforced concrete and steel bridges.
Library Quiz
Advances in structural design and earthquake engineering, such as PRESSS, base isolation and slotted beams, are being developed for a safer and more secure New Zealand.
To go in the draw to win a copy of Earthquake Engineering for Structural Design by Victor Gioncu and Federico Mazzolani answer the following simple question: Name the architects of the Public Utilities Commission’s (PUC) HQ at 525 Golden Gate Avenue in San Francisco?
To request your free copy of the Concrete Futures DVD email admin@ccanz.org.nz
Email your answer to library@ccanz.org.nz. Entries close Friday 31 May 2013. Congratulations to Pip Bolton of Fraser Thomas Ltd, who correctly answered the December 2012 Library Quiz to receive a copy of Detail in Contemporary Concrete Architecture by David Phillips and Megumi Yamashita.
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News from the Associations CONTACTS New Zealand Ready Mixed Concrete Association Ph (04) 499 0041 Fax (04) 499 7760 Executive Officer: Adam Leach President: Jeff Burgess www.nzrmca.org.nz New Zealand Concrete Masonry Association Ph (04) 499 8820 Fax (04) 499 7760 Executive Officer: David Barnard President: Mario Fontinha www.nzcma.org.nz Precast NZ Inc. Ph (09) 638 9416 Fax (09) 638 9407 Email: ross.cato_precastnz@xtra.co.nz Executive Officer: Ross Cato President: Paul Cane www.precastnz.org.nz New Zealand Concrete Society Ph (09) 536 5410 Fax (09) 536 5442 Email: concrete@bluepacificevents.com Secretary/Manager: Allan Bluett President: Jason Ingham www.concretesociety.org.nz New Zealand Master Concrete Placers Association Ph (07) 575 3214 Fax (07) 575 3618 Email: office@mcpa.org.nz www.mcpa.org.nz
NEW ZEALAND CONCRETE SOCIETY (NZCS) BASE ISOLATION 101 SEMINAR During late March engineers and other building professionals across New Zealand were fortunate to be addressed by two world leading experts in the field of base isolation as part of the NZCS and CCANZ’s Base Isolation 101 seminar. Ian Buckle, a Foundation Professor at the University of Nevada, Reno, and Ronald Mayes, Simpson Gumpertz & Heger’s base isolation project engineer, spoke on a range of topics related to the design and construction of base isolated structures. New Zealand was one of the first countries to implement base isolation with the construction of the South Rangitikei Rail Bridge in the central North Island (1976), followed soon afterwards by the William Clayton Building in Wellington (1981).
Ronald Mayes, Jason Ingham (NZCS President) and Ian Buckle
However, applications have not grown as rapidly as in other countries (especially Japan) for reasons that include a lack of understanding of the principles and benefits, a lack of analytical modelling skills, and a lack of confidence in the hardware. The seminar addressed all three of these concerns. Attendees left the seminar being able to determine the properties of a base isolation system to meet a required level of seismic performance, as well as make a first cut at the design of corresponding isolation hardware. Feedback has been so encouraging that a Base Isolation 201 seminar is being developed for possible scheduling in late 2013.
NEW ZEALAND ready mixed concrete association (NZRMCA) NZRMCA UPGRADES WEBSITE At the beginning of 2013 the NZRMCA launched its new website. Still found at www.nzrmca.org.nz, this online repository of all things ready mixed concrete in New Zealand is key to the Association’s communication strategy. The design of the website now complements the revised newsletter, as well as having a more efficient structure and an increased amount of New Zealand and overseas content. NZRMCA Executive Officer Adam Leach outlines the background to the project. “During 2012 the Council decided that a more proactive approach to member communications was required to raise awareness of the valuable initiatives the Association was under taking on behalf of the industry,” says Adam. “Along with the NZRMCA newsletter and better representation at regional meetings, the website forms the axis of information sharing tools used by the Association to alert members of new industry developments, best practice and regulatory responsibilities.” NZRMCA President Jeff Burgess is extremely pleased with the outcome. “Not only have we refreshed the look and feel of our website, but the ease with which it can now be updated will ensure more timely and relevant information is shared with industry,” comments Jeff. “Council is very aware of the need to demonstrate value to members, as well as meeting the Association’s core objectives of facilitating quality assurance / control, standards development, training, education and research, along with the general promotion of concrete. The new website will make these tasks much simpler.”
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