Concrete Magazine - Volume 55. Issue 02.

concrete VOLUME 55 ISSUE 2 JUNE/JULY 2011

2011 Concrete3 Sustainability Awards recognisiNG excellence in sustainable concrete construction

Weathertight Concrete Construction CCANZ CODE OF PRACTICE NOW AN ACCEPTABLE SOLUTION FOR NZ BUILDING CODE

Hobsonville Motorway Extension LATEST AUCKLAND ROADING PROJECT UNDERPINNED BY CONCRETE

THE MAGAZINE OF THE CEMENT AND CONCRETE ASSOCIATION OF NEW ZEALAND

UPFRONT The building and construction landscape is presently undergoing change at such a pace that remaining up-to-date with the numerous consultations, policy announcements and regulatory amendments has become a time consuming task.

The primary driver is of course the Christchurch, and greater Canterbury rebuild effort. Having presented the concrete industry’s views in relation to the Christchurch City Council’s draft Central City Plan, CCANZ is currently working on a response to CERA’s draft Recovery Strategy for Greater Christchurch.

concrete MAGAZINE

Editor/Advertising: Adam Leach +64 4 915 0383 adam@ccanz.org.nz Subscriptions: Kylie Henderson +64 4 499 8820 admin@ccanz.org.nz

Putting questions to one side about the draft Central City Plan’s restriction of building heights to 7-storeys, which many believe will send capital investment elsewhere, the Plan is to be applauded for its ambitious vision, and contains some unique opportunities for innovative concrete based technologies to enhance the urban landscape of a rebuilt Christchurch.

concrete is published quarterly

For instance, in the Plan’s theme of a Green City, the utilization of pervious concrete, concrete ¯ takaro corridor block permeable paving and concrete grid blocks will improve the Avon River/ O and water / environmental quality of the Central City, and help realise the “eco-street” concept.

Similarly, concrete’s durability, structural qualities and design flexibility in the creation of green roofs and walls has the potential to become the rebuilt City’s most visual commitment to environmental sensibility.

PO Box 448

The Plan’s Distinctive City theme calls for strong and resilient buildings that exceed the NZ Building Code’s seismic requirements, and in turn help produce a high quality built environment.

Recent advances in damage avoidance design systems using concrete systems, specifically PREcast Seismic Structural Systems (PRESSS) and Base Isolation, will play an important role in making this possible.

Fax: +64 4 499 7760.

One area of the plan where CCANZ urges explicit change are the noise provisions, which do not go far enough. Crucial to an inner city environment conducive to residential inhabitants is the capacity to safeguard people from distress as a result of undue noise being transmitted between abutting occupancies. While a minimum external sound insulation level is cited, there is no provision for internal sound insulation between tenancies. This is particularly important in mixed use multi-tenancy situations where ‘bass beat’’ can be a significant cause of distress between adjacent tenancies In addition to Canterbury focused activity, changes to the Building Code in the areas of practitioner licensing and weathertightness, along with mounting concerns over the nation’s skills and housing shortages, have also contributed to an extraordinary period of challenge and opportunity for our wider industry.

Key developments that relate specifically to the concrete industry are that Acceptable Solution B1/AS1 now references the updated NZ3604:2011, that all concrete slabs must now be reinforced and tied to perimeter foundations (unreinforced concrete slabs are not an option), and the definition of ‘good ground’ in the Canterbury earthquake region excludes ground subject to liquefaction or lateral spread. See page 4 for more details.

by CCANZ (Cement & Concrete Association of New Zealand)

Level 6, 142 Featherston St Wellington NEW ZEALAND Tel: +64 4 499 8820 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 2011 CCANZ (Cement & Concrete Association of New Zealand)

Finally, the CCANZ sponsored 2011 Concrete3 Sustainability Awards were presented in Rotorua recently in front of an audience of international and New Zealand based conference delegates.

Established in 2007 to raise awareness of concrete’s contribution to New Zealand’s sustainable development, the Concrete3 initiative has grown in strength.

The 2011 Supreme Award was presented to Peddle Thorp Architects for the adaptive reuse of a concrete frame building at 21 Queen Street in Auckland. Demonstrating the sustainability credentials of concrete on many levels, the outstanding feature of this project in my opinion was that it represents a different approach to problem solving, an unconventional way of overcoming a challenge. Such alternative methods will serve New Zealand well as we look to move forward and emerge more resilient and prosperous from our current set of circumstances.

Rob Gaimster CCANZ, CEO

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Cover photo: 21 Queen Street, Auckland.

2011 Supreme Concrete3 Sustainability Awards winner

NEWS Changes at the top FOR Golden Bay Cement & Firth Industries Fletcher Building has announced the appointment of Andrew Moss as Firth Industries’ new General Manager.

As the successful General Manager of Golden Bay Cement over the past four years Andrew has forged strong links across the cement and concrete industry. His already established relationships with Firth’s customer base and his exposure to the demands of the market mean he will be quickly able to grasp the challenges that currently face Firth.

Andrew Moss

David Peterson

Andrew took up the role on 1 October, at which point Fletcher Building began recruiting for his successor into the Golden Bay Cement General Manager position.

Andrew replaces David Peterson, who has taken up the position of General Manager with Fletcher Building’s EQR (Earthquake Recovery).

EQR was formed following the Canterbury September earthquake and took on a greater role following the February event in Christchurch.

EQR is charged with the rebuilding of residential properties damaged in Canterbury, on behalf of the Earthquake Commission. The role is Christchurch focussed, where David will now be based.

After almost 17 years with Firth, David leaves the company in good shape, ready to capitalise on new opportunities under the leadership of Andrew as the economy rebounds.

FIRE PERFORMANCE AND MASONRY STARTER BARS INFORMATION BULLETINS Concrete’s inherent properties, combined with the appropriate design of structural elements, ensure it performs well in a fire.

To assist with gaining an appreciation of concrete’s fire resistance IB 93 Fire Performance of Concrete and Concrete Masonry provides general guidance to designers and specifiers on the design of concrete structures against fire.

Along with the New Zealand Concrete Masonry Association (NZCMA) CCANZ has updated IB 47 Starter Bars – Concrete Masonry as part of a wider programme to bring the New Zealand Masonry Manual compilation in line with a range of recently revised standards – see page 39. IB 47 provides guidance for the correct positioning of starter bars for concrete masonry, and is applicable to 100, 150, 200 and 250 series walls built to a modular pattern.

Energy Efficient Our Insulated Masonry System incorporates 40/60 or 80mm insulation board to concrete structures providing a complete thermal envelope.

This System provides for the premium Rockcote flashing suite, and plaster coatings to provide a durable, low maintenance, and most importantly energy efficient structure now and into the future.

Both these IBs can be downloaded from the CCANZ website – www.ccanz.org.nz.

www.rockcote.co.nz 0800 50 70 40

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BUZZ from the Beehive Changes to the Building Code’s Supporting Documents for Structure From 1 August the Department of Building and Housing made changes to the NZ Building Code’s supporting documents for Structure. In short, Acceptable Solution B1/ AS1 now references the updated NZ3604:2011. There are also modifications such as, all concrete slabs must now be reinforced and tied to perimeter foundations, and the definition of ‘good ground’ in the Canterbury earthquake region excludes ground subject to liquefaction or lateral spread. See below for further details current at time of writing.

GUIDANCE ON REINFORCEMENT FOR CONCRETE SLABSON-GROUND Background The recent changes to the B1 Compliance Document require that concrete slabs-on-ground constructed in accordance with NZS 3604:2011 on good ground be reinforced with a minimum of 2.27 kg/m2 of Grade 500E reinforcing mesh fabric which conforms with AS/NZS 4671.

Issue Currently Grade 500E reinforcing mesh fabric of this specification is not available from any of the suppliers in New Zealand.

Interim Solution The Department has considered wire mesh product currently available in New Zealand. Grade 500E mesh fully complying with AS/ NZS 4671 is not yet available. Yield strengths are lower than 500 MPa and elongations are less than the 15% required for Grade 300E bar.

Therefore, to comply with the Building Code using an alternative solution as the means of compliance, reinforcing bars would need to be used (refer to Satisfactory Alternative Solutions using reinforcing bars).

However, the Department is issuing guidance under section 175 of the Building Act, advising that the option which follows provides an alternative solution using an equivalent capacity mesh as an interim measure.

It is the Department’s understanding that manufacturers will have Grade 500E reinforcing mesh fully compliant with AS/NZS 4671 available from October 2011.

Satisfactory Alternative Solution: Equivalent Capacity Mesh The steel properties of the mesh need to comply with the requirements of AS/NZS 4671, except that lower yield strength steel than that required for Grade 500E can be used, provided that an equivalent capacity in the slab can be achieved.

• The amount of steel (kg/m2) necessary to achieve the equivalent capacity is determined as: 2.27 x 500 divided by the Strength Grade of steel (where the strength grade of the steel is the verified lower characteristic yield strength of the steel bar in MPa).

• The uniform elongation Agt (refer Table 2 of AS/NZS 4671) must equal or exceed 10%.

• Properties are to be determined in accordance with Appendix C of AS/NZS 4671. Testing shall be carried out by independent

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qualified testing organisations and evidence shall be presented to Building Consent Authorities and to others on request.

Extensometer measurement taken across the necked portion of the test specimen shall be ignored.

• Reinforcing mesh fabric laps need to be a minimum of one grid wire spacing plus 50mm but not less than 150mm. Where deformed mesh wire with no cross wires is lapped with another sheet also with no cross wires, or where reinforcing bars are used, a lap length of 40 wire diameters or reinforcing bar diameters will be required.

• Reinforcement must be supported on chairs to ensure reinforcement position and 30mm top cover is maintained.

• Mesh shall be suitably identified to confirm conformance with these requirements.

Satisfactory Alternative Solutions Using Reinforcing Bars Reinforce the slab using either: • Grade 300E - DI0 reinforcing steel bars (conforming with AS/ NZS 4671) at 300mm centres each way with 30mm top cover, or • Grade 300E - D12 reinforcing steel bars (conforming to AS/NZS 4671) at 450mm centres each way with 30mm top cover.

GUIDANCE ON USING NZS3604 CONSTRUCTION ON GROUND WITH POTENTIAL FOR LIQUEFACTION Background The latest version, NZS 3604:2011, was published in February 2011, and is now referenced, with some modifications about reinforcing concrete slabs on ground and foundations, as an Acceptable Solution (B1/AS1) in the B1 Structure Compliance Document. With the modifications, the construction details in NZS 3604:2011, are suitable where there is “good ground” as defined in that Standard.

The referencing of NZS 3604:2011 with modifications as an Acceptable Solution applies to all regions in New Zealand. The modification to the definition of good ground made for the Canterbury Earthquake Region (to exclude ground subject to liquefaction or lateral spread) still applies, but only to that region.

It is clear that the issue of amending the definition of good ground to include consideration of potential loss of structural support due to liquefaction or lateral spread is both complex and not sufficiently well defined to incorporate in the B1 Compliance Document for the whole country at this point in time.

The Department is researching all the lessons learnt from the recent earthquakes, and will develop proposals that would provide robust and effective support for an amended definition of good ground in locations other than the Canterbury Earthquake region and will consult on these proposals.

In the interim, the Department has issued guidance available at: www.dbh.govt.nz/liquefaction-construction-on-ground-guidance For further information on changes in these areas regularly visit the DBH website – www.dbh.govt.nz.

CCANZ RESIDENTIAL CONCRETE CAMPAIGN COMING SOON Designed to raise awareness of the advantages of residential concrete construction, from floor slabs through to fully concrete houses, CCANZ will soon launch the Coming Home to Concrete initiative.

CCANZ chief executive Rob Gaimster believes that New Zealand currently has a unique chance to fully explore the possibilities that can be achieved through the use of concrete and concrete products in our homes.

Look out for the next issue of Concrete magazine or visit the CCANZ website (www.ccanz.org.nz) towards the end of October to find out more about the benefits of Coming Home to Concrete.

“As we move forward to tackle the challenges posed by the Canterbury rebuild as well as the predicted housing shortage in Auckland, the significant role concrete can play in providing comfortable, stylish and strong homes at affordable prices must be part of everyone’s thinking.

“The Coming Home to Concrete initiative will illustrate how we have the opportunity to enhance our residential building stock by utilising the many benefits of concrete, and in turn ensure resilient and healthy homes for all New Zealanders.”

Central to the Coming Home to Concrete initiative is a short film fronted by Kevin Milne (to be made available on DVD and online) that highlights the candid views of homeowners, architects and builders on the many positive attributes of concrete.

Along with the short-film, the initiative will provide a range of reader-friendly print and web-based resources to help all those involved with residential construction make informed choices and optimise the potential of concrete and concrete products.

Image: North Face Construction

When it comes to specifying concrete durability, waterproofing, and protection products, Xypex crystalline technology has no equivalent.

Xypex Admix C Series is accepted by Auckland City Environments as compliant with NZ Building Code Clauses B2 and E2, and by Good Environmental Choice Australia as compliant with GECA 08-2007 Environmentally Innovative Products Standard.

Call 07 575 5410 or visit: www.demden.co.nz

Concrete solutions

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Acceptable Solution for Weathertight Concrete Construction Added to NZ Building Code Documents Building a home to take advantage of concrete’s excellent weathertight credentials has become even simpler with a new Acceptable Solution that references CCANZ Code of Practice CCANZ CP 01:2011.

E2/AS3

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From August 2011 Clause E2 (External Moisture) of the New Zealand Building Code has an Acceptable Solution (E2/AS3) for weathertight concrete and concrete masonry construction that referenced CCANZ’s Code of Practice for Weathertight Concrete and Concrete Masonry Construction.

The Code of Practice covers the weathertightness of the building envelope for concrete slabs on the ground, concrete walls and associated methods of insulation, concrete flat roofs and decks, and concrete to timber construction junctions.

To aid planners and builders, the Code of Practice follows the same format as existing weathertightness solutions, but offers larger detail drawings following the text.

CCANZ developed the Code of Practice in partnership with building and construction industry representatives, and its acceptance into the New Zealand Building Code followed wider consultation by the Department of Building and Housing (DBH).

Image: Mercer and Mercer

CCANZ Chief Executive Rob Gaimster is delighted with the Code of Practice and believes it will bring real benefits to builders and home owners.

“The development of this document and its inclusion as an Acceptable Solution in the New Zealand Building Code will alleviate the current uncertainty amongst consent authorities in the area of weathertight concrete and concrete masonry design and construction.

To download [pdf 2.80 MB] or purchase a hardcopy of Code of Practice for Weathertight Concrete and Concrete Masonry Construction (CP 01:2011), go to the CCANZ website www.ccanz.org.nz

“It will also allow builders, designers and their clients to choose from a wider range of building materials, and in turn enable the weathertight advantages of concrete and concrete masonry systems to enhance New Zealand’s building stock.”

For further information about this key change to the NZBC External Moisture documents, go to the DBH website www.dbh.govt.nz

Weathertight Concrete and Concrete Masonry Construction

CCANZ CP 01:2011 Code of Practice for Weathertight Concrete and Concrete Masonry Construction

Cement & Concrete Association of New Zealand

June 2011

Cement & Concrete Association of New Zealand ◦ 2011

Image: Firth Industries

www.ccanz.org.nz

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CONCRETE INDUSTRY DEVELOPS SET OF STANDARDISED SAFETY HAND SIGNALS The New Zealand Ready Mixed Concrete Association (NZRMCA) has developed a set of standardised hand signals to assist clear communication with concrete truck drivers while on-site. incoming NZRMCA President, JEFF BURGESS, believes that the development of a universally recognised set of hand signals will contribute greatly to lessening the potential for incidents involving ready mixed concrete delivery.

“The NZRMCA Council takes matters of health and safety extremely seriously, and is committed to advancing the nationwide adoption of the new hand signals as a means to ensure the welfare of those who work alongside concrete truck operators.”

With close to 50 member companies, and nearly 180 plants across the country, it is more than likely that the majority of construction jobs involving ready mixed concrete delivery will be serviced by an NZRMCA member. For this reason, the NZRMCA recommends that along with its members, all those who work in the wider building industry adopt the set of hand signals.

The set of hand signals have been arranged in a poster format (similar to page 9) which is available for download from the NZRMCA website – www.nzrmca.org.nz The NZRMCA urge the distribution of the poster to all concrete truck drivers, plant staff, contractors, concrete placers, concrete pumpers, construction site workers, and ask that this one set of hand signals be used when working with concrete truck drivers.

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New Zealand Ready Mixed Concrete Association Inc.

Concrete Truck Driver Hand Signals Back up

Shift truck over

Stop truck, bowl

Arm bent at elbow, hand cupped.

Move arm back and forth towards the body.

Outstretched arms with open hands apart, clearly indicating where the truck is to be moved.

Arm bent at elbow, fist with knuckles facing outwards.

Move truck forward

Mix

Discharge bowl

Outstretched arm with hand out-stretched and thumb pointing upward.

Left hand palm facing up.

Right hand closed, fist rotating above left.

Arm bent at elbow, rotating clockwise.

Speed up bowl

Slow down bowl

Load finished, spin out bowl

Speed up, Lift outstretched arm, palm up.

Slow down. Lower outstretched arm, palm down.

Arm bent at elbow and quickly rotating in a clockwise (discharge) direction.

No response should be made to unclear signals Download the official Concrete Truck Driver Hand Signal poster from the NZRMCA website – www.nzrmca.org.nz

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2011 Concrete3 Sustainability Awards – Safeguarding Today’s Resources for Tomorrow CCANZ RECENTLY ANNOUNCED THE WINNERS OF THE 2011 CONCRETE3 SUSTAINABILITY AWARDS AT THE 9TH INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE CONCRETE IN ROTORUA.

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It is estimated that the 21 Queen Street project has made an embodied energy saving of around 29 percent by preserving the concrete structural frame. In operational terms, the energy saved when compared to an equivalent new build project would be enough to power the building for 14 years.

Stripping the site’s 14 level concrete frame of its cladding and fit-out, to form the heart of a refurbished and modern building, now teaming with over 300 office workers, also underpinned the project’s commercial viability, as well as breathing new life into the urban environment around Queen Elizabeth Square.

CCANZ chief executive, Rob Gaimster, said that through the reuse of a concrete frame building the project addressed all the economic, social and environmental imperatives of sustainable development, elevating it above a host of outstanding entries in 2011.

“This example of adaptive reuse will quickly become the New Zealand benchmark for what can be achieved in terms of optimum resource management, (embodied) energy efficiency and design potential, through the imaginative redevelopment of our concrete structures.”

On their way to the top prize, the team behind 21 Queen Street also received the Excellence in Commercial Concrete Construction award.

PROJECT PRINCIPALS

2011 SUPREME AWARD & EXCELLENCE IN COMMERCIAL CONCRETE CONSTRUCTION

Client: AMP New Zealand Office Trust Architect: Peddle Thorp Architects Consultant: Murray Jacobs Ltd + Norman Disney & Young Contractor: Fletcher Construction Company

Peddle Thorp Architects – 21 Queen Street, Auckland The transformation of an Auckland building from 1970s throwback to contemporary downtown landmark earned Peddle Thorp Architects the 2011 Supreme Concrete³ Sustainability Award. The team revitalised the multi-storey office building at 21 Queen Street, preserving its concrete frame and core while creating vibrant and thoroughly modern spaces inside and out.

The ‘reuse – reduce’ strategies adopted by the project principals, enabled the building’s life cycle to be significantly increased, the embodied energy of its concrete elements to be saved, and the emissions associated with alternative demolition and new build scenarios prevented – all key components to achieving environmental sustainability in construction.

Wade Jennings of Peddle Thorp Architects accepts the 2011 Supreme Concrete3 Sustainability Award from CCANZ CEO Rob Gaimster

“A really good way to reduce environmental impact is to build less. Our existing commercial structures present us with a tremendous opportunity to reinvigorate urban environments and target reduced energy consumption during construction, as well as improve energy efficiency during occupation. Winning the Concrete3 Sustainability Award is a fine endorsement of the collaborative approach and dedication of a talented design team and the vision of a forward thinking client.”

Wade Jennings, Associate Director, Peddle Thorp Architects

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EXCELLENCE IN CIVIL CONCRETE CONSTRUCTION Downer New Zealand- Dart 9 Manukau Rail Link Station The first new rail route to be built in Auckland since the Eastern Line in 1930, the 1.8km Manukau Rail Link connects the Manukau central business district to the North Island main trunk line, as well as the rest of the Auckland rail network. At the heart of the development is a 300m long, 18m wide, up to 7m deep trench near Haymen Park, which will house two platforms and the Auckland Regional Transport Authority’s rail link station.

Mark Hedley of Downer New Zealand accepts the Excellence in Civil Concrete Construction Award from CCANZ CEO Rob Gaimster

The wholly concrete station made significant use of secant pile technology, with over 600 piles, up to 1050mm in diameter, installed in the two parallel walls, with depths and diameters varying with the retained height. An important environmental attribute of this method of construction was that it required less earthwork disturbance around the structure compared to open-cut construction.

The project also illustrates how the properties of concrete can

is non-abrasive to skin and clothing, and greatly simplifies the removal of graffiti should this ever occur.

secant drilling to be carried out.

In the Manukau rail link station, the sustainable attributes of concrete have combined with quality workmanship, excellence in planning, design and attention to detail, to provide a cost effective, low maintenance structure well suited to serve the community and accommodate the resurgence of rail patronage in Auckland for many years to come.

The precast concrete panels used extensively throughout the

PROJECT PRINCIPALS

station were honed to a 5000+ grade reflective shine using Monarc

Clients: New Zealand Transport Agency (NZTA) and KiwiRail

technology. Besides the pleasing architectural finish, the intense

Consultant: Opus

colour contrast of the polished aggregate creates ‘visual noise’ to

Contractor: Downer New Zealand

deter tagging. In addition, the hard, smooth surface of the panels

Precast Concrete: Nauhria Precast

be varied to meet the demands of particular applications. For instance, a 40MPa 19mm aggregate mix with fly ash enabled a 100-year design life for the main structure and tension piles, while a 6MPa self-compacting concrete for the “soft” secant piles provided sufficient strength and water-tightness while allowing

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EXCELLENCE IN CONCRETE INNOVATION Structex Ltd - Southern Cross Hospital Endoscopy Building, Christchurch The vision for the Endoscopy Building was to house basement level and first floor level car parks, three operating theatres, a floor of consulting suites and a roof level plant room. The tight constraints of the site, coupled with a sophisticated set of requirements, dictated the need for an innovative approach.

The resultant PRESSS-based design utilised precast walls, beams and columns, joined in a ductile manner, combined with unbonded post-tensioned cables within the concrete members. The design provides sufficient strength and elasticity in the structure to resist large earthquake forces with minimal or no damage.

The post-tensioning restores the structure to its original vertical position after an earthquake event, allowing occupants to re-enter the building and continue with business as usual.

The largely theoretical seismic design performance goals of the project were put to the test during the February 22 earthquake, and proved so effective the Endoscopy Building was quickly called into service as a supplementary facility to the overloaded Christchurch Hospital.

PROJECT PRINCIPALS Client: Southern Cross Hospitals Consultant: Structex Contractor: Fletcher Construction Company

Structex proposed a PRESSS-based solution consisting of unbonded post-tensioned rocking/dissipative coupled walls and frame system, as it enabled speedy and more economical construction, while also delivering optimal seismic performance that would minimise business interruptions in the event of an earthquake.

The build included complex design analysis which allowed for a highly refined engineering solution and identified opportunities to further boost earthquake performance. These included the use of U-Shape Flexural Plates as coupling systems between adjacent post-tensioned walls to reduce the impact of an earthquake on the structure and contents of the building.

Stefano Pampanin, on behalf of Structex, accepts the Excellence in Concrete Innovation Award from CCANZ CEO Rob Gaimster

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EXCELLENCE IN CONCRETE FOR THE COMMUNITY Golden Bay Cement (GBC) Replacement of Fossil Fuels with Renewable Biofuel The use of wood as a sustainable biofuel is common overseas, but relatively new to New Zealand. It was selected by GBC as a substitute for fossil fuels in its cement kiln because its source is renewable, local, readily available and widely accepted by the community as a fuel. In addition, the wood

harvested forests. When left to decompose in forests and landfills, this material releases 2.7 tonnes of CO2e per tonne of material.

This is due to the more potent greenhouse gas (methane) that is released during decomposition. In this way, GBC’s use of wood as biofuel during 2009-10 has saved well over 100,000 tonnes of CO2e gases from being emitted.

GBC has plans to increase wood biofuel substitution beyond current levels. A recent trial of construction and demolition timber as a kiln fuel proved that the GBC Portland cement process is a very efficient and safe form of wood waste disposal, one which has received endorsement from the Northland Regional Council.

The wood biofuel initiative’s contribution to a sustainable built environment for New Zealand is no more succinctly conveyed than through a single figure - 25 percent - that being the approximate reduction of cement related CO2 emissions (from fuel) per cubic metre of concrete produced.

being burned is an industrial by-product that

PROJECT PRINCIPALS

would have otherwise ended up in a landfill.

Client: Golden Bay Cement

As the wood biofuel is sourced from commercially grown forests, and is therefore carbon neutral, its use by GBC contributes to a reduction in greenhouse gas emissions, and helps New Zealand to meet its Kyoto Protocol obligations.

In 2009 GBC had a 16.3 percent wood biofuel substitution rate.

The move to an average 25.2 percent in 2010 was the largest increase since the biofuel initiative was commissioned. Over the past 12-months the average substitution rate has increased to over 28 percent. GBC’s biofuel initiative is now one of the most significant contributors to Fletcher Building Limited achieving its target of a 5 percent reduction in 2007 Carbon Dioxide Equivalent (CO2e) levels by 2012.

Using wood as a biofuel has greatly reduced waste which would have otherwise gone to landfill or been dumped back into

Raki Harding of Golden Bay Cement accepts the Excellence in Concrete for the Community Award from CCANZ CEO Rob Gaimster

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EXCELLENCE IN RESIDENTIAL CONCRETE CONSTRUCTION Daniel Marshall Architects Elmstone House, Auckland The architect’s brief was to provide a family home on a suburban site that splays out from the end of a quiet Auckland cul-de-sac and slopes steeply away towards the North.

A heavy emphasis was placed on maximising open outdoor areas.

The strategy adopted was to build a house which took up the smallest possible space on the steep section ensuring ample ground was left for the young children to play on. To achieve this, while still allowing a sense of spaciousness, living areas are arranged vertically over three levels, each with its own distinct outlook toward a garden and pool. The home is enclosed beneath a single sloped roof, which allows variation of floor and ceiling levels to individualise the spatial experience throughout.

Precast concrete walls and simple concrete floors play against the sophisticated yet subtle detailing of more traditional residential finishes. The placement of exposed concrete elements within the home contributes to a thermal mass that absorbs the heat from plentiful northern and eastern sun. The combination of glazing and concrete mass regulates internal temperature fluctuations, to provide a healthy, comfortable and energy efficient internal living environment.

Social and economic efficiency are achieved through the use of precast concrete elements, which allowed for rapid construction on-site, and a durable family home such as this through being a robust, low maintenance material. The natural textures of concrete allow an open interior configuration with unique light qualities for the family’s enjoyment.

PROJECT PRINCIPALS Client: Ricketts Family Architect: Daniel Marshall Architects

Daniel Marshall of Daniel Marshall Architects accepts the Excellence in Residential Concrete Construction Award from CCANZ CEO Rob Gaimster

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Images: Emily Andrews

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The Pride, 2008 Supreme Concrete3 Sustainability Award winner

BACKGROUND TO CONCRETE3 Launched in 2007 by CCANZ, the Concrete3 programme of education, information and research seeks to raise awareness of concrete’s contribution to New Zealand’s sustainable development across all areas of economic, social and environmental endeavour.

Key to Concrete3 supporting innovative and sustainable concrete solutions for the built environment are the Sustainability Awards.

Presented annually, the awards provide architects, designers, engineers and/or industry with the opportunity to submit a concrete based product, project or initiative, substantially completed within the past three years, that demonstrates sustainability in either the production or use of concrete.

Each concrete based product, project or initiative entered may relate to any of the following areas: • Lean production less waste

• Respect for people

• Managing natural resources

• Minimising energy use

• Protecting against pollution

• Setting performance targets

The 2011 Concrete3 Sustainability Awards were selected from the following categories: • Excellence in Civil Concrete Construction

• Excellence in Concrete Innovation

• Excellence in Commercial Concrete Construction

• Excellence in Residential Concrete Construction

• Excellence in Concrete for the Community

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The Northern Gateway Toll Road, 2009 Supreme Concrete3 Sustainability Award winner

“Mix M” for the Tauranga harbour Crossing Stage 2, 2010 Supreme Concrete3 Sustainability Award winner

Within each category entries were judged by a panel of New Zealand and international industry experts, using an environmental, economic and social sustainability set of criteria. From the category winners, the Supreme Winner was selected.

When the awards began in 2008 the inaugural winner was The Pride, Lion Nathan’s integrated manufacturing and warehousing facility in East Tamaki, which incorporated recycled glass as aggregate in concrete.

The Northern Gateway Toll Road took home the Supreme Award in 2009 for the concrete lining in the road’s twin tunnels, which made extensive use of polypropylene fibres for fire resistance, and its bridge structures which used timesaving match-cast technology for the first time in New Zealand.

In 2010 Fletcher Construction’s concrete “Mix M” for Stage 2 of the Tauranga Harbour Link project received the highest accolade for being a significant step forward in mix design and durability modelling, one which combined enhanced environmental credentials with superior performance.

This year, the revitalisation of a multi-storey office building at 21 Queen Street, Auckland, which involved preserving its concrete frame and core while creating vibrant and thoroughly modern spaces inside and out, saw Peddle Thorp Architects rise above the competition.

For more information on the Concrete3 initiative and the Sustainability Awards visit www.sustainableconcrete.org.nz

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N Z I N FR A STR U C T U R E

HOBSONVILLE MOTORWAY On 6 August, six months ahead of schedule, the Hobsonville Motorway section of Auckland’s Western Ring Route was officially opened by the Prime Minister and celebrated by 10,000 sightseers at an open day. Besides 9KM of FOUR-lane deep-lift asphalt highway carrying 49,000 cars a day, the $220 million MOTORWAY includes two major concrete structures – the SH18/ SH16 flyover, and the Hobsonville Road Overbridge. Both structures involved innovations managed as a robust design-and-construct project which allowed construction to begin early and run in parallel with design. The innovations include a 4-lane bridge built entirely in-situ, and a “Green Wall” in which a 340m section of concrete fascia panels is broken up with live native plantings.

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N Z I N FR A STR U C T U R E

EXTENSION Overview The two main components of the project are (i) a 6km, four-lane motorway connecting the Upper Harbour Bridge and Greenhithe/SH18 in the east, to the Northwestern Motorway (SH16) in the west, and (ii) a 3km, four-lane extension of the Northwestern Motorway (SH16) from Westgate to a new roundabout at Brigham Creek Road.

Together these components form a key section of the planned 48km Western Ring Route motorway system linking South Auckland to the west and north, and will soon carry some 49,000

Graeme Cummings, HEB Structures, Project Manager

vehicles every day. Planners expect Auckland’s Northwest region alone to accommodate 330,000 new dwellings by 2040.

As the NZ Transport Agency’s (NZTA) main contractor, HEB Construction worked with up to 350 staff and subcontractors on site to deliver savings on time and cost, as well as environmental enhancements and minimised long-term maintenance. From sodturning to official opening took less than three-years.

Planning Intricate planning and attention to detail, combined with sufficient flexibility to adapt as required, was crucial to the project’s success.

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concrete 23

N Z I N FR A STR U C T U R E

For instance, initial design work called for the SH18/16 Flyover to contain trapezoidal fabricated steel box girders weighing an estimated 395 tonnes. However, the rapidly rising cost of steel encouraged a radical redesign to twin post-tensioned concrete box girders made fully in-situ, leading to a saving of about $500,000.

HEB Structures, Project Manager, Graeme Cummings, is of the opinion that the familiarity of working with concrete also offered advantages.

“An innovative planning feature of all five bridges except for the east-bound flyover”, says Cummings, “was the use of a portal frame design with sleeved piles instead of bridge bearings that would require periodic replacement. This feature gives the bridges an expected life of over 100-years with extended maintenance intervals”.

Another critical planning element was to resource and build a temporary roundabout and new bridge for Hobsonville Road traffic before commencing the major earthworks beneath the overbridge and the SH18/16 flyover. The project was the largest to date for HEB, who managed it alone without a joint-venture partnership, and completed the earthworks in three seasons instead of a typical four.

Perhaps the most innovative planning feature on the entire Hobsonville Deviation is the so-called environmental green wall which extends for 116m where the new SH16 passes beneath Hobsonville Road. A full scale trial wall was set up back in 2009 to test how concrete panels could provide shelter for small native plants while keeping their roots cool and moist.

SH18/16 Flyover The largest structure in the Hobsonville Deviation project is the flyover bridge where the two-lane east-bound SH18 from Waitakere to the North Shore crosses four-lane SH16 heading for Helensville.

Built fully in-situ, the flyover has two continuous 45m spans of trapezoidal post-tensioned concrete box beams with an insitu deck cast integrally at the centre piers. At the abutments and piers, the flyover stands on 22 bored pile foundations.

The flyover carries the Western Ring Route motorway with a height clearance of 6m for traffic on SH16. Some 20,000 precast concrete

An aerial view of the Hobsonville Road Interchange at Westgate.

Hobsonville Road Bridge carries local traffic over the 3km SH16 Brigham Creek Extension that continues beneath.

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keystone facing blocks form the wavy retaining walls that support the embankments to the flyover.

The facing blocks slope at 1:70 behind which retaining walls are built of mechanically stabilised earth (MSE). Placement of the blocks proved critical up to the full height to allow for construction of the abutments which were up to 50m long and contained 260m3 of concrete.

With its base slab, two external walls, two internal walls and deck slab, each of the two deck girders contained 175 tonnes of steel reinforcing.

The skew on the abutments was a massive 60 degrees, presenting a challenge to the team fitting the reinforcing into the girders and the diaphragms at each abutment. The girders required 2,000m2 of wall and diaphragm formwork, 1,500m of post-tensioning duct and 28,000m of stressing strand.

In all, the eastbound flyover contained 3,000m3 of in-situ and precast concrete.

Hobsonville Road Overbridge Carrying six-lane Hobsonville Road over seven lanes of SH16 and feeders, this intersection will cater for over 40,000 vehicles a day.

Some 200,000m3 of earth were excavated beneath the overbridge to enable construction of the Brigham Creek Extension to SH16.

The two span overbridge contains 24 1500mm deep reinforced Super Tee beams with a concrete deck resting on 18 piles sunk 8m into the rock. The Super Tee design involved fully integrated construction with no articulation or movement joints at either piers or abutments. The bridge retaining walls contain more than 1,000 “soil nails”.

Concrete parapets for the Underpass extend 134m and required 50m3 of concrete. The 14m deep cut under the bridge is faced each side with large soil nailed walls with precast facing panels.

Green Wall Along a 116m section of the west-facing retaining wall of the Hobsonville Road Overbridge, large vertical concrete facing panels up to 16m high are cast in patterns containing a grid of

The flyover provides a seamless connection between SH16 and SH18 as part of the northern section of the Western Ring Route.

N Z I N FR A STR U C T U R E

To North Shore

Whenuapai

2011

Whenuapai Airbase Helensville-North Shore: Join the new SH18 at Brigham Creek Road and cross the Upper Harbour Bridge

ron

ad Squ

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n Roa

Ro a

d

Sinto

vil le

E ILL NV N SO TIO B HO EVIA D

ve

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Hobsonville Point: Going to the new development at Hobsonville Point? Exit SH18 at Squadron Drive (going west) or Brigham Creek Road (going east)

North Shore-Westgate/Massey: Visiting friends in Hobsonville from the Shore? Exit the motorway at Squadron Drive or Brigham Creek Road and turn onto Hobsonville Road

Ho

Trig R oad

Brigham Creek Extension: Travelling to the city? Join the Northwestern at Brigham Creek Road roundabout and keep going past Westgate.

The first exit is at Lincoln Road

ve yA kle

Buc

e Lan e rks idg Claootbr f

bs on

oad Creek R ham Brig

K EE CR M ION HA S IG EN BR EXT

ive Fred Taylor Dr

To Helensville

Upper Harbour Bridge

Monterey Park

SH18/16 Flyover

Westpark Marina

Helensville-Westgate: Going shopping at Westgate? Take Fred Taylor Drive to Don Buck Road.

Top Tip: Use local roads for local trips – it will save you time

Westgate Shopping Centre

Don Buck

Road

West Harbour

SH16

To Auckland City

circular holes for live vegetation arranged in rising curves to represent “lines of the land”.

Known as the Green Wall, this section has a truly innovative design specifically developed for the project. Space restrictions required the wall to be vertical, and as it faces the live motorway, long-term maintenance also had to be minimal.

The full-scale trial wall built in 2009 tested the concept using various plant species, soil/fertiliser blends and reinforced mesh bags stacked against a reinforced shotcrete face supported by soil nails, in turn protected by a long-life epoxy to resist corrosion.

Trial precast facing panels were installed against the reinforced mesh bags. It was discovered that only west-facing panels would provide protection for the vegetation from the full glare of the sun. The 9-month trial provided other design parameters to allow maximum survival for the various plants species, which are now left alone and watered only by natural rain.

Concrete Stats The concrete volumes for the Hobsonville Motorway Extension project were significant, as indicated by the facts and figures below: • In total the project consumed some 15,300m3 of concrete • 15km of concrete pipe were used to divert streams.

SH18

New bridge

• Retaining walls were stabilised with soil nails and shotcrete • Decorative finishes were pre-cast into all facing panels and blocks • Most of the precast concrete was manufactured locally and transported a short distance Enjoy the Benefits By providing a motorway alternative to SH1, the new Hobsonville motorway improves transport links between the north, west and south of Auckland, including Auckland International Airport.

The NZTA Regional Director for Auckland and Northland, Stephen Town, believes the project provides a transport backbone for the developing areas of north-west Auckland, and improves safety by taking thousands of vehicles off the old congested State Highway along Hobsonville Road.

“It will reduce travel times by up to six minutes and make journey times more reliable for commercial drivers choosing to bypass the Auckland Harbour Bridge”.

The project’s innovative use of concrete will be seen by fans travelling the new shorter route between Albany Stadium on the North Shore and Eden Park.

• Parapets running for 724m required 284m3 of concrete

Design & Construct Contractor: HEB Construction

• Concrete panels covering 5,467m required 1,142m of concrete

Designers: Aurecon

2

3

• The 34 No 1500 Super Tee Beams for Honsonville Road and Totara Creek Bridge required 667m3 of concrete • The bridges at Buckley Road, Brigham Creek Road and Trig Road required 34 No 1200 Super Tee Beams, totaling 668m3 of concrete

Consultants: Opus and AECOM Concrete supplier: Allied Concrete Concrete pre-caster: HEB Structures Text by: Tom Evison, Technical Press Service

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concrete 25

N Z I N FR A STR U C T U R E

THE PERFECT SOLUTION

CEMENT TREATED SUB-BASE FOR THE MANUKAU HARBOUR CROSSING SINCE ITS EARLY COMPLETION IN AUGUST 2010 THOSE WHO HAVE BENEFITTED FROM THE COMPONENTS THAT MAKE-UP THE MANUKAU HARBOUR CROSSING MAY NOT HAVE BEEN AWARE OF THE INNOVATIVE ROADING TECHNOLOGY BENEATH THEIR WHEELS. HOWEVER, THE SUCCESS OF THIS KEY LINK IN THE WESTERN RING ROUTE CHAIN OWES A LOT TO CEMENT TREATED SUB-BASE (CTB).

At its initial stage, the Manukau Harbour Crossing was a competitive alliance contract where two teams were selected by the client organisation (Transit New Zealand – now New Zealand Transport Agency - NZTA) to progress design and pricing of the $230 million project. From this the NZTA selected their preferred team based on cost and non cost attributes, to form an alliance.

The non owner participants comprising of consortia made up from Fletcher Construction, Beca and Higgins won the right to the design and deliver the project with NZTA. These three companies formed an alliance team with NZTA referred to as the Manukau Harbour Crossing Alliance (MHX).

The Manukau Harbour Crossing project involved: • Widening the existing SH20 motorway between Walmsley Road and Queenstown Road • Duplication of the existing Mangere Bridge • Modification or replacement of five existing bridges • Median divided carriageway with four lanes in each direction between Rimu Road and the Gloucester Park interchange and a minimum of three lanes in each direction in other areas • A bus shoulder in both directions 26 concrete

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Early in design and pricing, the MHX team considered six pavement options. The consumer price indices in 2007/2008 were starting to increase significantly so it was imperative that the team delivered a pavement design that was less sensitive to rising material costs using bituminous products; a design that delivered whole of life benefits, and a design that was competitive in the market.

The answer arrived at by the MHX team was to go with a cement treated sub-base layer (CTB) that was overlayed by asphalt base and wearing course layers. A lot of work went into understanding the differences in thermal behaviour and potential risks/effects between cemented and asphalt layers. Various ways to mitigate thermal cracking were discussed, with asphalt that was rich in polymer modified bitumen being the eventual solution.

Such a cutting edge design posed many challenges for the construction team charged with delivering the final product. As quality was critical, aggregate selection, binder supplier, moisture content assessment, mixing process, delivery process, laying and compaction process, curing and post construction process were all thoroughly reviewed and revised during construction. The MHX team had to achieve tight tolerances on depth, moisture and cement contents, as well as density and deflection criteria. Such specific needs could only be met using state of the art equipment.

• Wirtgen KMA 200 pugmill mixer for on site mixing • Vogele 1603 tracked paver (which has a TP1 screed and pressure bar system) equipped with Topcon mmGPS machine control.

• On site laboratory • Pneumatic Sakai vibrating PTR roller • A dedicated crew that would start and finish the job The pavement itself was designed for a 25-year design life. The design consisted of a stabilised subgrade, four percent CTB and two overlaying structural asphalt layers followed by a final wearing course.

N Z I N FR A STR U C T U R E

Grant Higgins, Alliance Project Manager, Manukau Harbour Crossing Alliance The production of 90,000 tonnes of CTB over a 12-month period was carried out on site using the Wirtgen KMA 200 pugmill plant.

KMA pugmill accuracy in dispensing water and cement, the mixing process, and the use of aggregate from Brookby Quarry resulted in a design resilient modulus better than anticipated, which in turn allowed for a reduction in cement content.

Before each production shift the moisture content of the stockpiled Manarc MR9 40 basecourse was checked. Once the moisture content of the stockpiled material was established the KMA operator would add the additional water required during the mixing process to achieve the optimum moisture content for compaction. The KMA operator could adjust the water and / or cement quantity in the control cabin. There were a few checks and balances to ensure material weigh-out corresponded with the metering. Other procedures, such as double checking cement dispensing against each production shift, were also instituted.

A real benefit of the KMA pugmill was its closeness to site, which allowed for better control of moisture content from load-out to discharge into the paver. The aggregate was fed into the KMA by loader. Water and cement were added to the aggregate as it entered the mixing bowl of the KMA. After mixing, the CTB travelled up the conveyor where the material was loaded into six or eight wheeler trucks. Due to the large amount of aggregate, rehandling and stockpile management are essential during the operation. Procedures to minimise possible segregation were also introduced. Once on site the CTB material was tipped into the hopper of the paver. Again, segregation was important, in particular, ensuring the hopper did not run low and accurate timing of the tripping tailgates and hopper wings on the paver.

A millimetre global positioning system (mmGPS) unit was set up on the paver to control the paved levels, in what was possibly the first example of its type in the world. Although this was successful,

it became apparent to the MHX team that the level control system on the graders did not adequately address the relationship between paved mat bulking factors and variation in the underlying surface. For instance, significant variance in the underlying surface was reflected through to the paved surface. To resolve this issue the MHX team quickly adapted the grader to run with the same mmGPS system.

Due to the overall thickness of the CTB layer (generally 300mm) it was paved in two layers. Initial rolling was performed using a 10 tonne vibrating roller, followed by a vibrating PTR roller, with final compaction performed using an 11 tonne static roller. The majority of the CTB was paver laid, with a small percentage being grader laid where areas were restricted in size or access.

Curing of CTB was carried out over a 2-3 day period, and a water cart was continually used to moisten the surface to prevent it from drying out. After the curing period, the CTB was pre-cracked using a vibrating steel roller, and then an emulsion prime coat was applied.

There were huge time savings through paver laying the CTB as compared to traditional grader laying. However, strong subgrades, along with levels within tight tolerances, had to be ensured.

Careful planning was also required to ensure productivity and efficiency were maximised. Processes and checking regimes were also in place to deliver quality outcomes (productivities and achieved level thicknesses were constantly reported) as the underlaying cement layer needed to be carefully looked after through the cracking and curing process.

The construction of Manukau Harbour Crossing’s CTB layer was a significant and invaluable learning experience for all involved.

The efficient delivery of a quality product, at a demanding site, using advanced pavement technology, was testament to the MHX team’s dedication and commitment to delivering what has already become a vital component of Auckland’s infrastructure. volume 55 issue 2 JUNE/JULY 2011

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concrete 27

N Z I N FR A STR U C T U R E

Highway E17, Belgium

COMBI

SLAB ROADS ALAN ROSS

BUSINESS DEVELOPMENT MANAGER BOSFA NEW ZEALAND

Raupuha Road tunnel in Taranaki 28 concrete

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N Z I N FR A STR U C T U R E

AN IMPORTANT DESIGN CONSIDERATION FOR ANY CONCRETE STRUCTURE IS THE LOCATION AND DETAILING OF JOINTS. THIS CAN BECOME PARAMOUNT FOR CONCRETE ROADS WHERE JOINTS HAVE TRADITIONALLY BEEN THE ACHILLESâ&#x20AC;&#x2122; HEEL OF THIS FORM OF CONSTRUCTION. BEING ABLE TO MINIMISE OR ELIMINATE JOINTS IS AN ATTRACTIVE PROPOSITION IN TERMS OF ONGOING MAINTENANCE COSTS. This is one of the main reasons Continuously Reinforced Concrete Pavements (CRCP), which are designed to eliminate the need for joints, are often preferred over jointed pavements with large numbers of closely centred crack control joints. CRCP are designed with enough steel reinforcing to keep the inevitable cracking within acceptable parameters. By typically utilising 16mm or 20mm reinforcing bars at close (<200mm) centres, the requirement for crack control jointing, such as saw cut joints, is removed.

Innovation in this field of concrete design has led to the development of designs rules that make it possible to use steel fibre reinforced concrete (SFRC) in combination with conventional reinforcing.

Providing New Zealandâ&#x20AC;&#x2122;s

concrete answers

When concrete cracks steel fibres have the ability to provide tension across the full crack depth, absorbing some of the energy released and effectively reducing the tension in the main steel reinforcement crossing the crack. The result is smaller crack widths and tighter crack control or less main reinforcement for the same crack width. To illustrate this point; assume a concrete tensile strength of 3MPa and a post crack tensile strength, provided by fibre reinforcement, of 1MPa. Only 2/3 of the cracking load has to be considered for the design of the main crack control reinforcement when taking into account the contribution from the steel fibres. In addition to this, and often not utilised in design of pavements, is the increase fatigue resistance and load carrying capacity provided by the SFRC. The Raupuha Road tunnel located on a back road deep in Taranaki, was required to be designed with no joints along the length of the tunnel. This meant there is 110m between joints and the CombiSlab jointless panel has a remarkable length to breadth ratio greater than 30:1. Dramix SFRC Grade 35MPa FL 3.0 / 3.5 (NZS3101:2006) was used in combination with one layer of mesh (A = 314mm2/m). Being able to use one layer of mesh instead of potentially two layers or reinforcing bars, simplified construction, improved crack control and reduced cost.

The E17, a major Belgian highway was recently constructed with a lane using a Dramix SFRC in combination with 20mm reinforcing bars.

Crack width is an important parameter for the long term performance of CRCP, particularly the development of punch outs (pavement failure). Using CombiSlab enabled a reduction in calculated crack width and allowed a reduction in longitudinal reinforcing.

NZS3106:2009 Design of Concrete Structure for the Storage of Liquids provides recommendations on how to calculate crack widths in reinforced concrete, taking into account expected stress distribution and the age of concrete when this cracking may occur. This is state-of-the-art. These procedures can easily be modified to take into account the positive effective of SFRC. The combination of using SFRC and conventional reinforcing can significantly reduce the expected crack width and has a strong effect on the amount of bar or mesh required when designing for crack control.

Enjoy the benefits of membership www.ccanz.org

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concrete 29

N Z I N FR A STR U C T U R E

INTER-ISLAND LINK POLE 3

Transpower is carrying out a project to replace Pole 1 of the inter-island HVDC link with a new pole by 2012. Mainzeal is the civil subcontractor for this project, and is contracted to Siemens, who in turn is working for Transpower.

The project has an element of dĂŠjĂ vu to it because 20 years ago Mainzeal was on site at Haywards and Benmore building the converter stations for Pole 2.

The Benmore and Haywards converter stations form the end points of the main power transmission lines from the South Island hydro to the lower North Island. High voltage power is converted from AC to DC at the Benmore end for transmission purposes and then reconverted at the Haywards end for distribution to the network.

The new pole (to be known as Pole 3) will be a state of the art thyristor valve unit and together with the existing Pole 2 will increase the capacity of the overall HVDC inter-island link to 1000 MW from 2012, and 1200 MW from 2014. Once Pole 3 is built, the old Pole 1 will be fully decommissioned and removed.

Mainzeal is constructing a control building of approximately 1,400m2 in footprint at both the Haywards and Benmore sites.

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Central to the building is the valve hall and along its side are the three transformer rooms. At one end are the support spaces including areas for the safety systems and the control room.

The buildings have been designed for a 100-year life span and to also withstand a 2,500-year earthquake event. The floating slab sits on base isolators and sliders sourced from America. The building is designed to move 750mm in all directions on the horizontal plan and return to its original position after the event.

A substantial amount of the project scope involves the belowground works. For the Haywards building, the foundations consist of 83 piles with depths ranging from just 2.5m through to over 25m. The raft slab is 500mm thick and carries the 83 bearer plinths

N Z I N FR A STR U C T U R E

DEJA VU FOR MAINZEAL

END CLIENT: Transpower MZ CLIENT: Siemens ARCHITECT: CCM Architects

and inverted slider plinths. Above the raft slab is the base isolated floating slab and remaining structure to house the sensitive equipment required to convert DC-AC or AC-DC. The Benmore building is similar but it does not require the piles.

Due to the nature of the site, earthing is a significant feature of the project. Under the whole switch yard site is a copper earthing grid and all buildings and major plant are connected to it to ensure there is no difference in potential across the site. As well as there being many connections from the building structure and reinforcing within the concrete back to the earthing grid, large items of construction plant such as cranes are required to be connected to the copper earthing grid with what could be described as large jumper leads.

Understandably on the Benmore site, the cold weather and remote location have posed challenges. The issue of cold temperatures has been overcome by tenting the concrete pours with a large heated marquee. The remoteness of the site has required the establishment of a mobile concrete batching plant in nearby Otematata and the setting up of a mobile crushing/

STRUCTURE: Aurecon SERVICES: Aurecon

screening plant just down the road. All the excavated material has been recycled back to the site as hard fill.

Technical design challenges associated with achieving the seismic stability of the buildings and the three 20 tonne thyrester valves housed within the valve halls put significant pressure on the construction programme so Mainzeal re-planned the build phase to recover time.

Months were taken off the original build programme by changing the major spine walls and buttress walls from in-situ concrete to 50 tonne precast wall sections. The main spine wall on each site is 40m long by 20m high and 300mm thick. The tower cranes were replaced with 200 tonne mobile crawler cranes to handle the heavy panels.

Prefabricated roof sections which were fully clad, lined and fitted out were another time saving construction feature Mainzeal employed to assist the programme. The roof sections were built on the ground and lifted into position when the main valve hall foundations and wall structures were complete. Using prefabricated roofs meant there was minimal time needed to complete the internal fitout once they were in place.

Article reproduced with kind permission from Mainzeal Property and Construction â&#x20AC;&#x201C; www.mainzeal.co.nz

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concrete 31

U K I N FR A STR U C T U R E

ROADS GET GRINDING

& GROOVING

AS BUDGETS GET SQUEEZED, DIFFERENT APPROACHES TO COST that can EFFECTIVELY EXTEND THE LIFE OF ROADS ARE BEING EXAMINED. ONE OF THESE CURRENTLY BEING EXAMINED BY THE HIGHWAYS AGENCY [IN THE UK] IS DIAMOND GRINDING AND GROOVING. SUCCESSFULLY USED FOR MANY YEARS IN THE UNITED STATES, THE PROCESS RESTORES THE SURFACE PERFORMANCE OF A CONCRETE ROAD AT LESS THAN HALF THE COST OF OVERLAYING THE CONCRETE WITH ASPHALT. In addition to cost savings, the process is fast, is environmentally friendly (as it has a lower carbon footprint than asphalt overlay) and provides a road surface that is noticeably quieter than untreated concrete, as traffic driving over a textured surface emits less noise than when driving over a smooth surface.

Grinding and grooving involves plant equipped with closelyspaced diamond-tipped saw blades that cut drainage and traction grooves into the tired road surface. With grinding, 3mm to 10mm of the concrete pavement is treated to leave a level, high performance riding surface. The closely spaced grooves left after 32 concrete

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volume 55 issue 2 JUNE/JULY 2011

grinding provide a high level of texture and friction. The same technique and plant is used for diamond grooving. Whereas the purpose of grinding is to restore ride quality and texture, grooving is generally used to reduce hydroplaning by providing channels for water drainage. In terms of design, the main difference between grinding and grooving is in the distance between the grooves â&#x20AC;&#x201C; about 6 times greater for grooving. Introduced into the UK by Concrete Cutters (Sarum) Ltd, in partnership with UK abrasives company, Tyrolit, the diamond grinding technique is half the cost of overlaying concrete with asphalt, is much faster and requires considerably less investment in capital plant.

U K I N FR A STR U C T U R E

Last year, the Highways Agency has carried out a series of grind and groove trials in East Anglia at Alconbury Airfield, in Cambridgeshire, between the A318 and A1114 junctions on the A13 Chelmsford Bypass, and in Essex on the A12 Chelmsford Bypass. Further trials have been carried out on the 1.61km of the A12 Kelvedon, in both directions, 745m of the A12 Chelmsford Northbound, 1km of the A11 Ketteringham Northbound and a major maintenance project on the A14 near Ipswich has used the technique. Early indications from accelerated wear tests are that the surface is durable and will retain its skid resistance and noise attenuation characteristics for many years. There has been a significant improvement in skid resistance of 54 percent. Reductions in noise levels compared with a smooth concrete surface with traffic flowing at 30 to 50mph range from 4 – 6dBA. Transport Research and Development (TRL) is monitoring all the sites and at higher vehicle speeds the noise reduction is even more apparent. It is anticipated that the results of the TRL study will be published later this year.

The first major project on the A14 involving four 6km land with a total area of 125,000m2 was successfully completed in May. The main contractor was VolkerFitzpatrick and the scheme was carried out within Highways Area 6 and was supervised by W.S.Atkins.

Experience in California, a pioneer of the grind and groove technique, has found that whilst asphalt overlays typically last 8 to 12 years, the average life span of a diamond ground concrete surface is up to 17 years and a pavement can be diamond ground up to three times without significantly affecting its structural performance. Other benefits include that the process can be carried out during off-peak hours with short lane closures and without encroaching into adjacent lanes. Grinding one lane does not require grinding of the adjacent lane which may still have acceptable surface friction and drainage, and the clearances underneath bridges are not affected.

It is estimated that there are nearly 1,350 lane kilometres of concrete roads in the UK that need attention. With its considerable potential cost savings and long term performance benefits grinding and grooving offers the enticing possibility of its being used on new build and major reconstruction road projects. This has successfully been done in the USA and, in a time of cut backs and slashed budgets, could result in concrete roads making a comeback in the UK. Article reproduced with kind permission of Britpave - www.britpave.org.uk

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Resene X-200 uniquely combines low viscosity with high build ensuring excellent penetration into cracks and pores and superb adhesion. It develops into a tough, durable and continuous membrane, while its fibre reinforcement increases tensile strength. Resene X-200 is a popular choice for refurbishments in areas prone to earthquakes and for concrete buildings nationwide.

And it’s available in an extensive range of Resene colours including the heat reflective Resene CoolColour technology.

Protect your concrete projects with Resene X-200 and keep them looking good long into the future. Available from Resene ColorShops and Resellers.

See the Resene Paint systems for earthquake affected buildings booklet available online at www.resene.com/ aftertheearthquake for recommended paint systems for restoring homes and buildings after an earthquake.

0800 RESENE (737 363) • www.resene.co.nz

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concrete 33

U K I N FR A STR U C T U R E

Fig 1. Tievenameena Bridge, UK

A Flexible Concrete Arch System Dr Su TAYLOR, Reader in Structural Engineering, Queenâ&#x20AC;&#x2122;s University Belfast, s.e.taylor@qub.ac.uk Abhey GUPTA, Production Manager, Macrete Ltd, Toomebridge, Northern Ireland, abhey@macrete.com MASONRY ARCH BRIDGES ARE ONE OF THE OLDEST FORMS OF BRIDGE CONSTRUCTION AND HAVE BEEN AROUND FOR THOUSANDS OF YEARS. THEY WERE ORIGINALLY BUILT OF STONE OR BRICK BUT ARE NOW BUILT OF REINFORCED CONCRETE OR STEEL. THE INTRODUCTION OF THESE NEW MATERIALS ALLOW ARCH BRIDGES TO BE LONGER, LOWER IN HEIGHT AND EITHER CAST ON SITE OR MANUFACTURED AS PRECAST.

Fig 4. Arch Unit before Lifting

Fig 5. Arch Unit during Lifting

Fig 6. Arch Unit after the lifting

Fig 10. Positioning of the first arch ring

Fig 11. Positioning of the subsequent arch rings

Fig 12. Installation of spandrels

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U K I N FR A STR U C T U R E

However, a common problem with such bridges is corrosion to reinforcement, which can lead to high repair and maintenance costs. Therefore a bridge with no or low amounts of reinforcement is a significant step change and should provide improved durability and whole life performance.

In recent years a novel flexible concrete arch system, FlexiArchTM which requires no steel reinforcement has been developed under a Knowledge Transfer Partnership (KTP) between Queen’s University Belfast (UK) and Macrete ltd (UK) . The arch is constructed from a ‘flat-pack’ system which uses a polymer reinforcement for carrying the dead load during construction, but behaves as a masonry arch bridge once in the arch form.

THE SYSTEM FlexiArch is a modular, precast, concrete arch bridge system. The FlexiArch system is based on the same principles as traditional stone masonry arch bridges dating from Roman times – but without the stone mason and without the need for labour intensive centering. Individually cast concrete voussoirs (tapered blocks) – precast with the correct taper for a given span and rise – are connected by a polymeric flexible membrane, which allows the arch to fall into form as it is lifted from flat pack into position.

FlexiArch can be used for any kind of crossing, underpass or highway bridge replacement for up to a 10m span (a 15m span is under development) and up to a 4m rise. FlexiArch flexible arch rings are made in 1m widths. As such a FlexiArch bridge can be installed using any number of 1m wide units. The maximum width currently is 80m, equating to 80 arch rings connected side by side.

Fig 2. Polymeric Reinforcement Fig 3. Construction of arch unit using pre-cast individual voussoir concrete blocks

per metre, equating to a peak strip capacity of 6kN. Concrete for casting the voussoirs is standard structural 50MPa typical in precast concrete elements. a. Production The voussoirs are precast individually, laid contiguously horizontally with a layer of polymer grid material placed on top.

The individual voussoirs are then interconnected by an in-situ layer of concrete which is placed on top (Fig. 3). The arch unit is generally cast in 1m widths which is the a balance between lifting capacity and lateral stability. b. Lifting

DETAILS OF ARCH SYSTEM The advancements in composite material technology and the ability of the polymer in this system to be sufficiently strong yet flexible is one of the keys to the success of the arch. This reinforcement is a geogrid (Fig. 2) with a manufacturer’s specified strength in the longitudinal direction of 80kN/m. Polyester is used as the reinforcement material, encased in a plastic outer sheath for protection to the fibres. There are thirteen longitudinal strips

When lifted off-site for demonstration purposes, the wedge shaped gaps close, hinges form in the top layer of concrete and the unit is supported by tension in the polymeric reinforcement grid (Fig 4-6). The arch shaped unit is then placed on a precast footings or anchor blocks. When in the final arch position, the self-weight is carried by compression in the arch ring and the arch behaves similarly to an un-reinforced masonry arch.

Fig 7. Arch Unit transportation

Fig 8. Seating units in place above the foundation

Fig 9. Lifting sequence

Fig 13. Backfill is in place

Fig 14. Stone facing to the bridge

Fig 15. Finished bridge volume 55 issue 2 JUNE/JULY 2011

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- transducers

centre of axle load moved to critical locations

- vibrating wire gauges - fibre optic sensors to measure strains between joints

Stability test: front deflections

+1m 0m -1m

2500 0.5m fill

2000

VW4 VW3

VW5

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1500

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clear span = 5.00m

transducer position arch Load 17: deflection x 10 Load after 17 hours: deflection x 10

500

H7

H1 V1

V7

0 0

Fig 16. Monitoring of the arch during backfill operations.

c. Transportation A FlexiArch bridge is transported on site completely flat – on a number of flatbed transporters (Fig. 7). The components include the correct number of flexible arch rings for the width of the crossing, together with precast spandrels walls which can be supplied with a decorative finish or stone work finish. The spandrels form the outside finish to the bridge and do not carry any traffic loads. However, they do act as permanent shuttering for the poured concrete infill, and transfer the load to the arch and the foundations from the road pavement. d. Construction When lifted on-site, the wedge shaped gaps close, hinges are formed in the top screed layer and the units are supported by tension in the polymer reinforcement. The arch ring is then placed on precast seating units or anchor blocks and when in the final position, the self-weight and vehicle loading is carried by compression in the arch ring, that is, the FlexiArch behaves similarly to an unreinforced masonry arch.

When all the arch rings for the required bridge width are in place, the spandrels are installed into position and secured with a push-pull rod fixed to the arch rings. The time for this installation is between 4 and 8 hours. The bridge is then ready for granular backfill or concrete infill, covered by the roadway finish and levelling, and any parapets required for the category of bridge.

STRUCTURAL TESTING AND ANALYSIS OF ARCH SYSTEM Stability and loading testing Substantial testing and monitoring of the FlexiArch system has been carried out by Queen’s University Belfast (QUB).

The most significant tests were: • Arch ring stability testing during backfilling operations • Loading test of the arch ring and the full bridge system During the stability test, the arch was monitored for horizontal and vertical deflections (to give overall vectored deflection) and to measure the strain at the voussoirs joints, i.e. the opening in the tension face. Fig. 16 shows the instrumentation set-up. The backfilling operation was carried out by placing 250mm deep layers of concrete to each side of the arch to minimise asymmetric loading. The results of the monitoring showed very little movement in the arch ring and it was concluded that the arch was highly stable under the backfill operations (Fig. 17).

Following successful analysis and testing of the prototype 1m-wide arch ring, a 5m-wide arch bridge was constructed at Macrete Ltd. The bridge was load tested with the aim of proving the strength of the arch bridge under a critical third-span loading condition and to beyond the current EU axle loading. The second and fourth arch rings, immediately below the simulated wheel load positions, were monitored throughout the duration of the test. The arch bridge system with concrete backfill was capable of supporting at least a third-span load of 74.3 tonnes. There was no visible cracking in 36 concrete

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1000

2000

3000

4000

5000

Fig 17. Arch after completion of the backfill operation.

the arch bridge and no detectable movement at the abutments.

The maximum test load was over six times the current wheel load. The maximum deflection was 0.48mm, which was equivalent to (effective span/12476). The maximum deflection occurred under the load (at third span) and there was over 50% recovery in deflection after removal of all load. This is a good recovery for an applied load which was over six times the current wheel load. The strain values were also very low, indicating low levels of stress in the arch intrados.

Analysis of arch unit An analysis of the arch unit was conducted using ARCHIE M (5), a mechanism analysis package, which allows for interaction with the arch backfill. It is important to note that this software is also used by the DRD Road Service in Northern Ireland for load assessment analysis of their arch bridges. Therefore, validation of the manufactured arch unit using ARCHIE was an important task in the development of the arch system. A typical case of arch unit analysis is shown under design loading; with the position of the thrust line in the arch unit giving information about the stability of the unit. Analysis has also been carried out using non-linear finite element analysis.

SUSTAINABILITY FlexiArch requires no internal steel reinforcement. As a compression structure, it is self-supporting by virtue of its own weight without the aid of mortar. Without a steel rebar content, the possibilities for internal corrosion, rebar expansion, and resultant concrete cracking or spalling, are eliminated. This increases the whole life performance of the bridge compared to other steel reinforced systems used for this span of bridge.

CONCLUSION AND FURTHER RESEARCH The collaboration between QUB and Macrete under a Knowledge Transfer Partnership has enabled the transfer of research to a practical and more durable bridge structure. Current developments have been limited to a square bridge system but many bridges do not cross perpendicular to the obstacle below.

Hence a skew FlexiArch bridge system is needed to further enhance the uptake of this system.

REFERENCES • T aylor S E, Gupta A, Kirkpatrick J, Long A E, Rankin G I B and Hogg I, ‘Development of a novel flexible concrete arch system’, 11th International Conference on Structural Faults and Repairs, Edinburgh, June 2006.

• T aylor S E, Gupta A, Kirkpatrick J and Long A E, ‘Testing of a flexible concrete arch system’, Proceedings of the seventh New York Bridge Conference, August 2007.

• G rattan S K T, Taylor S E, Basheer PAM, Grattan K T V, Sun T and Gebremichael Y M, ‘Novel Fibre Optic Sensors for Monitoring of Bridges’, Proceedings of Bridge Engineering in Ireland Conference BEI06, December 2006.

• O BVIS Ltd. ARCHIE-M: Masonry Arch Bridges and Viaduct Assessment Software, Version 2.0.8, UK, 2006.

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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. DISPLACEMENT BASED SEISMIC DESIGN OF STRUCTURES BY M.J.N. PRIESTLEY, G.M. CALVI AND M.J. KOWALSKY Displacement-Based Seismic Design of Structures is a book primarily directed towards practicing structural designers who are interested in applying performance-based concepts to seismic design. Since much of the material presented in the book has not been published elsewhere, it will also be of considerable interest to researchers, and to graduate and upper-level undergraduate students of earthquake engineering who wish to develop a deeper understanding of how design can be used to control seismic response.

SOIL LIQUEFACTION DURING EARTHQUAKES BY I. M. IDRISS AND R. W. BOULANGER This text updates a subject area covered in the 1982 classic text used around the world, Ground Motions and Soil Liquefaction During Earthquakes,

by H. Bolton Seed and I.M. Idriss.

The following areas are covered: â&#x20AC;˘ Fundamentals of liquefaction behavior: a framework for a common understanding of the development and limitations of various engineering analytical procedures. â&#x20AC;˘ Liquefaction triggering analysis: methods for evaluating the potential for liquefaction triggering. â&#x20AC;˘ Consequences and mitigation of liquefaction: examples of lateral spreading and post-liquefaction settlement analyses, the use of factors of safety in engineering practice, mitigation strategies, and methods for ground improvement. â&#x20AC;˘ Cyclic softening of saturated clays: engineering procedures for evaluating the potential performance of cohesive fine-grained soils.

Library Quiz To go in the draw to win a copy of Displacement Based Seismic Design of Structures by M.J.N. Priestley, G.M. Calvi and M.J. Kowalsky answer the following simple question: The Southern Cross Hospitalâ&#x20AC;&#x2122;s Endoscopy Building in Christchurch emerged unscathed from the February 22 earthquake. What advanced, concrete based, structural system did the designers employ?

Email your answer to library@ccanz.org.nz. Entries close Friday 4 November 2011.

Congratulations to Vanessa Beavon of Selwyn District Council, who correctly answered the March / April 2011 Library Quiz to receive a copy of Solid States: Concrete in Transition edited by Michael Bell and Craig Buckley.

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CONTACTS New Zealand Ready Mixed Concrete Association Ph (04) 499 0041 Fax (04) 499 7760 Executive Officer: Rob Gaimster President: Jon Hambling www.nzrmca.org.nz New Zealand Concrete Masonry Association Ph (04) 499 8820 Fax (04) 499 7760 Executive Officer: David Barnard President: Jason Savage 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: Andrew Sinclair 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 (06) 873 4428 Fax (06) 873 4429 Email: office@mcpa.org.nz www.mcpa.org.nz

News from the Associations NEW ZEALAND CONCRETE MASONRY ASSOCIATION INC. (NZCMA) CONCRETE MASONRY MANUAL UNDERGOING REVISION The manual was created in the late 1970s and periodically reviewed as Standards change. The last major review was in 1999 although the Design Section was up-graded in 1999 and 2004 to match the issues of NZS 4229 and NZS 4230.

A decision has been made to completely update the technical contents of the manual, and to make it available on the NZCMA website (www.nzcma.org.nz) where it can be viewed and downloaded in sections as required.

The process is on-going, with Parts and Sections uploaded to the website as they become available. Work has seen Part 1 General Sections 1.1 – 1.7 completed and on the website with Parts 3, 4, 5 and 6 currently under various stages of review.

The full project is expected to be complete by mid 2012.

NEW ZEALAND CONCRETE SOCIETY (NZCS) HPC Symposium and Concrete Conference Report Around 350 people from 40 countries attended either or both the 2011 Concrete Conference and the International Symposium on High Performance Concrete (HPC) held in Rotorua during August.

Michael Khrapko, Symposium Chairman, said the event was very successful and the quality of papers exceptionally high. A highlight was a dinner in honour of Professor Pierre-Claude Aïtcin of Sherbrooke University, Canada, whose lecture was titled ‘Improving the Sustainability of HPC’.

NZ Concrete Industry Conference Organising Chairman Jason Ingham acknowledged Michael Khrapko for making the Symposium such a success, and commented that the one-day NZ Concrete Industry Conference enjoyed strong attendance despite the economic climate, shortened format and relocation from Christchurch.

The NZ Concrete Industry Conference keynote speaker, Adjunct Professor Des Bull from the University of Canterbury and a member of the Urban Search and Rescue team involved immediately after the Christchurch earthquake, presented insights associated with the performance of concrete structures during the earthquake.

The conference closed with a presentation on the Victoria Park tunnel.

Technical Information

NEW ONLINE RESOURCE

Your one-stop, online resource that has everything you need to know about Pipeline, Watermain, Drainage and Environmental products

www.humes.co.nz/technical

Check it out now! volume 55 issue 2 JUNE/JULY 2011

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concrete 39

application innovation.

Duomix Fire anD Dramix, the right Fibre For each application. www.bosfa.com

Duomix Fire and Dramix breaking new ground – Victoria Park tunnel.

Duomix Fire m6 – passive fire resistance, precast panels Duomix Fire M6 are 18 μm diameter, 6mm long synthetic fibres and were used as passive fire protection in the precast wall panels, an effective and reliable measure against explosive spalling. Research has shown that the fineness of the fibre and ultimately the number of fibres per cubic meter of concrete is a dominant factor controlling their effectiveness.

Dramix – crack control, primary shotcrete lining Dramix steel fibre reinforced concrete (Grade 30MPa FL 3.0/2.5; nZS3101:2006) was used in combination with traditional reinforcing in the watertight shotcrete layer; this can significantly reduce crack width and or the required amount of reinforcement.

other suitable applications For Dramix combineD with traDitional reinForcing:

REALISE GREATER EnGInEERInG EFFICIEnCY WITHOUT COMPROMISInG QUALITY On YOUR nEXT PROJECT. TALk TO THE LEADER IN FIBRE REINFORCED CONCRETE ENGINEERING CALL 1300 665 755 (AUS), 0800 665 755 (nZ) OR vISIT bOSFA.COM

LL_BOS3814_0111

– Liquid tight structures; basement slabs, industrial slabs with hygiene requirements or subjected to hazardous liquids – To limit the number of joints in roads and in commercial slabs – Where SLS crack control is critical and governs over ULS design