Concrete VOLUME 61 ISSUE 1 - CONCRETE INDUSTRY ON TRACK TO MEET 2030 EMISSIONS REDUCTION TARGET
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concrete VOLUME 61 ISSUE 1 CONCRETE INDUSTRY ON CONCRETE ROAD PAVEMENTS TRACK TO MEET 2030 EMISSIONS COULD HOLD THE KEY TO NZ’S REDUCTION TARGET DURABILITY ISSUES
THE MAGAZINE OF CONCRETE NZ
concrete
UPFRONT MAGAZINE
Editor/Advertising:
ACCOUNT FOR Adam Leach
CARBON OVER +64 4 915 0383
adam@concretenz.org.nz
A BUILDING’S Subscriptions:
WHOLE-OF-LIFE Angelique Van Schaik
+64 4 499 8820
admin@concretenz.org.nz
While New Zealand looks to recover from the effects of COVID-19,
it must also remain focussed on emissions reduction, a key aspect concrete is published quarterly
of which will be adopting a whole-of-life approach to determining by Concrete NZ
the environmental impact of construction.
PO Box 448
Recovery from the pandemic is the absolute priority, not just for the Level 4, 70 The Terrace
building and construction sector, but for all New Zealand. Wellington
NEW ZEALAND
Government stimulus through fast-tracked, large-scale projects,
and plans to address deferred maintenance in schools, hospitals, Tel: +64 4 499 8820
is required to create jobs and help New Zealand emerge Email: admin@concretenz.org.nz
Website: www.concretenz.org.nz
from recession.
At the same time however, another national priority is to remain ISSN: 1174-8540
on-track to meet our part in reducing emissions under the
ISSN: 1174-9374 (online)
Paris Agreement.
Disclaimer: The views expressed in concrete
A crucial mechanism to ensure net zero carbon is achieved by are not necessarily those of the Concrete NZ.
2050 will be climate change regulations across all sectors, including While the information contained in the
magazine is printed in good faith, its contents
building and construction.
are not intended to replace the services
of professional consultants on particular
While the Climate Change Response (Zero Carbon) Amendment Act
projects. The Association accepts no legal
offers a defined, long-term, emissions target, with an assured responsibility of any kind for the correctness
framework for managing the transition to a low-emissions future, of the contents of this magazine, including
advertisements.
decisions must be evidence-based and deliver pragmatic results.
© Copyright 2020 Concrete NZ
It was therefore, concerning to hear Urban Development Minister,
Phil Twyford, announce that Government procurement rules now Advertorial
require departments constructing new buildings to select materials
(and processes) with the lowest ‘upfront’ carbon emissions.
While the concrete industry acknowledges that the built
environment, including infrastructure, is a significant contributor to
New Zealand’s emissions, the most appropriate way to compare the
environmental impact of buildings is a ‘cradle-to-cradle’ (not ‘cradle-
to-gate’) Life-Cycle Assessment (LCA).
An LCA from a recognised provider uses robust science and
independent data to assess a building’s impact across its entire life
cycle. Such a methodology considers the product, construction, use,
end-of-life and recycling / recovery / reuse stages.
As with the new Government procurement rules, the Ministry of
Business, Innovation and Employment’s (MBIE) Building for Climate
Cover images: The sustainability properties of concrete in use.
2 concrete VOLUME 61 ISSUE 1
Change programme appears to have adopted an failures on the Kapiti and Waikato Expressways
upfront approach to assessing embodied carbon. emphasised the need for procurement and
construction to provide quality and productive
MBIE’s Whole-of-life embodied carbon emissions
outputs.
reduction framework, which seeks to improve the
operational efficiency of buildings by reducing In targeting net zero carbon by 2050 New Zealand
emissions, reducing water use and improving must learn the lessons of recent decades when
occupant health and wellbeing, is proposing rapid reform led to unintended consequences
an LCA approach that stops at the gate not such as the weathertightness debacle, the costs
the grave. of which will have to be met by generations
to come.
We acknowledge that extensive consultation,
including with industry, is being undertaken by Rob Gaimster
MBIE, and look forward to collaborating in the Concrete NZ, Chief Executive
development of a sustainable final framework.
At the same time, Concrete NZ will continue to
advocate for a whole-of-life approach with Waka
Kotahi NZ Transport Agency (NZTA), which has
just formed a partnership with the Infrastructure
Sustainability Council of Australia (ISCA) to deliver
sustainable outcomes.
We encourage the partnership to consider the
whole-of-life, cost effective case for concrete road
pavements, particularly as a review of pavement
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and future maintenance costs. Protecting reinforcing
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Make the best long-term sustainable investment for your concrete assets.
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VOLUME 61 ISSUE 1 concrete 3
FEEDBACK SOUGHT ON
TECHNICAL SPECIFICATION FOR
CONCRETE FLOOR SURFACE
REGULARITY
CONCRETE NZ IS SEEKING FEEDBACK ON ITS DRAFT TECHNICAL SPECIFICATION 01:2020 SURFACE
REGULARITY REQUIREMENTS FOR CONCRETE FLOORS.
The technical specification provides surface requirements currently provided in NZS 3109
regularity requirements for internal concrete Concrete construction and NZS 3114 Specification
floors that are either supported by the ground or for concrete surface finishes.
are suspended.
Copies of the draft Technical specification 01:2020
The technical specification’s provisions can apply Surface regularity requirements for concrete floors
to a range of building uses including industrial, can be downloaded from the Concrete NZ
warehousing, institutional, retail, commercial, website - www.concretenz.org.nz
office and accommodation, where different
You can submit your feedback by e-mailing
tolerances are required for the specific use (e.g.
admin@concretenz.org.nz
high reach forklifts) and/or take account of final
floor finishes that may be applied (e.g. tiles). The closing date for providing feedback is
30 October 2020.
Guidance on methods for measuring surface
regularity is also provided.
The requirements in the technical specification
modify and/or supersede surface regularity
4 concrete VOLUME 61 ISSUE 1
PRECAST CONCRETE Justin Bragg
Concrete NZ Precast
PANEL LIFTING ANCHORS -
Sector Group
DO NOT TAKE SHORTCUTS
THOSE WHO WORK WITH PRECAST PANELS ARE BEING WARNED BY CONCRETE NZ AND WORKSAFE
TO ENSURE THEY MEET INDUSTRY STANDARDS FOLLOWING A SERIOUS NEAR-MISS INCIDENT.
In December 2019, a precast concrete panel “It is critical that the material of the installed
which weighed 20 tonnes was being lifted at an anchors meet the requirements of specified
Auckland construction site when the cast-in lifting industry Standards. Anchors and the lifting
anchor failed and the panel fell. While no one was clutches should both be made of an appropriate
injured the risk of serious injury was high. ductile material to avoid brittle failure.”
Following the incident WorkSafe carried out Justin is confident that Precast Sector Group
testing which confirmed the failed lifting anchor members are well aware of the risks and source
was made from a brittle material and therefore lifting anchors from reputable suppliers, but is
should not have been used. The lifting anchors reminding non-members of the risks around
had been self-imported by the manufacturer. purchasing a non-compliant product.
WorkSafe’s Principal Engineer, Stuart Wright said “The risks of this are potentially increased when
WorkSafe engaged with the manufacturer of the sourcing offshore products where the quality
precast panels to determine if any other panels and testing regimes may not meet the specified
existed with the same brittle lifting anchor. requirements. We are reminding everyone to
“WorkSafe is satisfied all panels containing keep in mind that when self-importing products
anchors from the same batch as the failed anchor additional testing may be required to ensure the
have already been erected or positioned without product conforms to New Zealand requirements.”
further incident. The manufacturer of the precast Further guidance on the roles and responsibilities
panels has voluntarily surrendered to WorkSafe, for the safe handling, transportation and erection
all of the unused lifting anchors that were of precast concrete elements can be found in the
supplied in the same batch.” WorkSafe document Safe work with
Justin Bragg, of the Concrete NZ Precast Sector precast concrete: Handling, transportation and
Group, said the design and installation of lifting erection of precast
anchors should only be carried out by those concrete elements -
with experience. www.worksafe.govt.nz
VOLUME 61 ISSUE 1 concrete 5
CONCRETE PUMPING Richard Sands
Concrete NZ Readymix
HEALTH & SAFETY
Sector Group Chair
GUIDANCE UPDATED
THE CONCRETE NZ READYMIX SECTOR GROUP HAS ISSUED AN UPDATED SAFETY ALERT: BLOW-BACK
& PUMP-BACK1 DOCUMENT, THAT URGES ITS READY MIXED CONCRETE PRODUCER MEMBERS TO NO
LONGER ACCEPT BLOW AND PUMP BACK FROM CONCRETE PUMPS.
Richard Sands, Chair of the Readymix Sector pumping equipment and the environment this
Group, believes the procedure poses significant equipment is used in.”
health & safety hazards for all those involved and “Health & safety vigilance needs to be
should not be undertaken. maintained across the supply, acquisition,
“Blow and pump back entails moving residual disposal, inspection,
concrete from the line or boom pump back into maintenance,
registration and safe
the truck mixer bowl under pressure, and can be
operation of all types
very dangerous.”
of concrete pumps
Concrete NZ is advising against the practice of and associated
accepting blow and pump-back from all line and placing equipment
boom concrete pumps due to the potential risks used in pumping or
involved,” says Richard. spraying concrete.”
1. The Safety Alert - Blow-
The Readymix Sector Group also strongly Back & Pump-Back can
encourages those involved in concrete pumping be downloaded from the
Concrete NZ website –
to adhere to the Ministry of Business, Innovation www.concretenz.org.nz
and Employment’s (MBIE) Concrete Pumping Health
2. The Concrete Pumping
and Safety Guidelines2. Health and Safety Guidelines
can be downloaded from the
“This Guide provides practical advice about the WorkSafe NZ website –
safe operation and maintenance of concrete www.worksafe.govt.nz
6 concrete VOLUME 61 ISSUE 1
We produce and supply consistent quality cement that
you can rely on. We call it NZ grade - you know where it’s
made, what it’s made of, who made it and that it’s made
for the NZ market. It’s Genuine so you can trust it.
Being Genuine is part of our fundamental
approach to do business.
Our
NZ made
cement is
genuine
NZ grade
cement
CONCRETE MASONRY
SITE PRACTICE AND
WORKMANSHIP GUIDE
PUBLISHED
THE MASONRY SECTOR GROUP HAS PUBLISHED A CONCRETE MASONRY -
SITE PRACTICE AND WORKMANSHIP GUIDE TO HELP DEVELOP COMPETENCY Ralf Kessel
Concrete NZ Masonry
LEVELS ACROSS THE MASONRY TRADES. Sector Group Convenor
“This Guide is intended for use by all members of has a consistent appearance and
the building team, including site supervisors and needs little or no maintenance during its design
brick and block layers,” says Concrete NZ architect life,” says Ralf.
and Masonry Sector Group convenor Ralf Kessel.
“Units, mortar, grout, rebar and other ancillary
The Concrete masonry - Site practice and components such as beams and columns must
workmanship guide: also be designed and specified in accordance
with the New Zealand Building Code and relevant
• covers the key points for preparing and
Standards.”
carrying out masonry work onsite,
• includes extracts from relevant Standards and The Concrete masonry - Site practice and
Codes of Practice for easy reference; and workmanship guide can be downloaded from the
Concrete NZ website –
• provides a handy action checklist.
www.concretenz.org.nz
“High levels of workmanship and site practice
should result in durable brick and blockwork that
MISSED THE SEMINARS?
TRY WEBINARS
THE WRECKAGE FROM COVID-19’S SLIPSTREAM INCLUDES THE DISRUPTION OF THE SOCIETY’S
SEMINAR PROGRAMME – THE FIRST EVENT WON’T TAKE PLACE UNTIL LATER THIS YEAR.
But members may be interested in the pair of
webinars we have created from two seminars
SEM
held last year – particularly if you were not able INAR
SERI
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019
to make those events. If we can take anything
ASSESS
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BUILDI ENT OF EXIST
‘positive’ from the virus, it is the proof that
NGS US I
ING TH NG CONCRET
webinars are an effective way of reaching people
C5 GUI E REVIS
– even in extraordinary circumstances. DELINE E
S ED
The two webinars are Strut & Tie (held in Presen
ted by
Concret
e NZ –
September last year), and Assessment of existing Learned
Society
concrete buildings using the revised C5 guidelines, WHY Y
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within NZS 3101 Concrete structures standard, it has Brooke, Principal at Compusoft Engineering and
not (until recently) been widely covered during Learned Society President.
structural engineering courses.
SEMINAR COSTS
The seminar (webinar) was (is) presented by Des
Bull (a Technical Director of Holmes Consulting The Strut & Tie webinar comprises four sessions
Group LP), and Rick Henry (senior lecturer in priced at $160+GST. The C5 webinar comprises
the Department of Civil and Environmental six sessions priced at $240+GST. Once
Engineering at the University of Auckland). purchased, they are available to view for seven
days (Note: the webinars must be viewed on-line
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– they cannot be downloaded – and they must be
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viewers’ schedules) within
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BCITO CEO WARWICK QUINN
APPOINTED NZ INSTITUTE OF
SKILLS & TECHNOLOGY (NZIST)
DEPUTY CHIEF EXECUTIVE
BCITO CHAIR, MIKE KING, RECENTLY ANNOUNCED THAT CEO WARWICK QUINN HAS BEEN
APPOINTED NZIST DEPUTY CHIEF EXECUTIVE, EMPLOYER JOURNEY AND EXPERIENCE. QUINN WILL
TAKE UP THE NEW ROLE IN NOVEMBER 2020.
In announcing Mr Quinn’s departure, Mr King
said, “While we are disappointed that Warwick
is moving on from BCITO, we look forward to
continuing to work closely with him in his new
capacity. Warwick’s deep knowledge of vocational
education and on-job learning along with his
energy and huge drive to make it the best it
can be, have contributed immensely to BCITO’s
success and will continue to be of enormous
value to the industry.”
In accepting the role Mr Quinn said, “Vocational
education is something I care passionately about,
so this is an opportunity I could not refuse. At
BCITO we’ve developed a robust on-job training
system that works efficiently and is tailored to the
needs of the individual industry sectors under
our coverage. I look forward to continuing to work
closely with employers across a range of sectors
to ensure we deliver great training outcomes for
New Zealand.”
Mr King commented that it has never been
more important to have a strong, unified, and
sustainable system for vocational education. He
said, “We need to do everything we can to retain
apprentices and trainees in the system, so we
don’t waste their learning and we have a capable
workforce ready to support the recovery.”
BCITO has just over 14,000 active trainees and
apprentices. Apprenticeship sign-ups reached an
all-time high in July, and this trend has continued
into August. Last year, building and construction
was New Zealand’s third largest sector, directly
contributing $19 billion to the country’s GDP.
Warwick Quinn, Chief
Mr King commented that BCITO has a strong Executive Officer, BCITO
leadership team in place, “I have complete faith
and confidence in the BCITO leadership team.
They are well-positioned to pick up from Warwick The BCITO Board has appointed Greg Durkin as
in the interim and lead BCITO forward as we move Interim Chief Executive until a permanent candidate
into the new RoVE environment,” he said. is secured.
10 concrete VOLUME 61 ISSUE 1CONFERENCE 2021
14-16 OCTOBER 2021
ENERGY EVENTS CENTRE
ROTORUAFEEDBACK RECEIVED ON
FUTURE OPTIONS FOR
CONCRETE STANDARDS
Dave McGuigan, Concrete NZ Technical Director
THE PREVIOUS ISSUE OF CONCRETE MAGAZINE OUTLINED WHY IT IS TIME TO CONSIDER A
MORE STREAMLINED FRAMEWORK FOR THE SUITE OF STRUCTURAL DESIGN STANDARDS.
In particular, the options proposed in my 2019 to around four which would cover design,
Concrete NZ conference paper - The building production, concrete materials, and construction
code system and a future direction for Standards Of the twenty plus current New Zealand
that support the NZ concrete industry, should be Standards for concrete the three considered to
considered. be most in need of updating were:
In early 2020, Concrete NZ conducted an online • NZS 3109:1997 Concrete construction
survey seeking its members’ feedback on options • NZS 3101:2006 Concrete structures
to rationalise, maintain and fund the current
• NZS 3114:1987 Specification for concrete
collection of Standards, as well as potentially surface finishes
adopt international Standards.
It must be noted that NZS 3104:2003 Specification
The survey findings provided some interesting for concrete production is currently under review,
and useful responses, the key elements of which with a 2020 version expected to be published
are outlined here. shortly.
RATIONALISE STANDARDS MAINTAINING STANDARDS
The survey indicated strong support (90 The survey also revealed overwhelming support
percent) for rationalising the current framework for the establishment of ‘Standing Committees’
of concrete Standards, reducing the number (94 percent).
12 concrete VOLUME 61 ISSUE 1This was seen as a way to provide more consistent Zealand Building Code and the wider building
monitoring of the maintenance and development regulatory system.
needs of Standards, facilitate succession planning
Survey respondents also signalled their belief that
and better inform the ongoing research needs to
secondary funding should come from industry, as
support Standards revisions.
has been the case with New Zealand ready mixed
Most survey respondents had not been on concrete producers funding – through Concrete
a Standards Committee (79 percent), with NZ - the review of NZS 3104.
some respondents expressing the view that
Other themes expressed from survey participants
the Standards development process required
included the requirement for more regular
improvement and that Standards committees
updates of Standards, and that the documents
need to be more balanced and have ‘relevant’
themselves be simplified to make them more user
representatives.
friendly and enable compliance to be more easily
The belief that committee members should be demonstrated.
compensated for their time also came through
clearly in the responses. MOVING FORWARD
Next steps may include widening the survey
INTERNATIONAL STANDARDS audience to seek feedback from other groups,
The survey asked participants if they favoured such as members of the Structural Engineering
maintaining existing New Zealand Standards Society of New Zealand (SESOC), a key user group
versus adopting international design Standards, of structural design Standards.
with opinion divided equally.
The direction of the Ministry of Business,
Of those that supported adopting international Innovation and Employment’s (MBIE) Building
Standards preference was spread between System Performance branch to implement a long-
American Concrete Institute (ACI) and Eurocode term Standards development programme will also
documents, with a lower level of support for be clarified.
developing joint AS/NZS Standards.
This will help broaden discussion, inform decision
making and ultimately set the future direction that
FUNDING STANDARDS
the construction sector, in partnership with MBIE
The survey indicated that the funding for the
as the building regulator, will take to safe guard
development of Standards should come primarily
these important documents that help achieve
from Government and/or the Building Levy,
consistent outcomes for the built environment.
respecting that Standards support the New
VOLUME 61 ISSUE 1 concrete 13The upgrade and extension of 133 Molesworth Street in Wellington showcases many of concrete’s sustainable attributes.
CONCRETE INDUSTRY
ON TRACK TO MEET
EMISSIONS REDUCTION
TARGET
Rob Gaimster, Chief Executive, Concrete NZ
THE NEW ZEALAND CONCRETE INDUSTRY IS HALFWAY TOWARDS MEETING ITS TARGET OF A 30
PERCENT REDUCTION IN CARBON DIOXIDE EMISSIONS BY 2030, AND IS FULLY COMMITTED TO
BECOMING NET CARBON NEUTRAL BY THE GOVERNMENT’S TARGET DATE OF 2050.
A recent review by independent sustainability The emissions reduction occurred against a 13
consultancy thinkstep, found the New Zealand percent increase in demand, which demonstrates
concrete industry is well placed to meet how committed we are to sustainability.
climate change commitments the New Zealand
government signed up to under the Paris We are pleased that our initiatives to reduce
Agreement. cement’s carbon footprint have avoided about
400,000 tonnes of carbon dioxide emissions in
The independent review confirmed that the
2018 alone.
New Zealand concrete industry has reduced its
emissions from cement by 15 percent between The reduction in emissions has been achieved
2005 and 2018. through a range of measures, including the use
14 concrete VOLUME 61 ISSUE 1Concrete is critical to wastewater management as demonstrated by the recent BNR upgrade of
Mangere Wastewater Treatment Plant.
Shredded vehicle tyres will soon be used at
Wood waste (biomass) at Golden Bay Cement’s Portland works is used as a partial replacement for Golden Bay Cement’s Portland works as a
coal as kiln fuel. partial replacement for coal as kiln fuel.
of waste products such as wood biomass to fuel foundations, we receive healthcare in hospitals
cement kilns. built from concrete, and many of us work in
Concrete NZ’s Sustainability Committee has concrete buildings.
met Climate Change Minister Hon James Shaw Concrete also underpins our water and sewerage
and Dr Rod Carr (Chair of the Climate Change systems and will be crucial in the development of
Commission) to share the thinkstep results and low energy infrastructure that includes electricity
discuss how concrete is part of the transition to a generation and public transport.
net zero carbon New Zealand by 2050.
As we adapt to climate change and our planet
A game-changer for the industry here in New warms, concrete will offer protection against fire
Zealand is that we have available naturally and floods, while its mass will help regulate the
occurring minerals that can be used to replace a
internal temperature of buildings to reduce our
percentage of cement clinker, which is the main
reliance on energy intensive air conditioning.
ingredient of concrete production associated with
carbon dioxide emissions. The environmental benefits of concrete are
significant. Concrete structures act as carbon
Waste from other industries are also being used
sinks, they can also be recycled, redesigned and
to lower the cement clinker content in concrete
repurposed. Concrete structures require little
and help to significantly reduce concrete’s
carbon footprint. maintenance, and don’t rot or burn.
At the same time, moving to new technologies, Our industry knows how important concrete is
such as more energy efficient equipment and to everyone’s future wellbeing. That’s why we’re
vehicles to produce and transport concrete, is working so hard to reduce our carbon footprint
part of our plan to be net carbon neutral by 2050. and maximise the benefits of concrete.
Concrete is the second most consumed
substance in the world after water and is central
to supporting communities and economies
around the world.
Our kids walk to school on concrete footpaths,
they learn in schools that rest on concrete
VOLUME 61 ISSUE 1 concrete 15FACTSHEET
NZ CONCRETE INDUSTRY
EMISSIONS REDUCTION
The New Zealand concrete industry is halfway towards meeting its
target of a 30 percent reduction in carbon dioxide emissions by 2030.
Independent sustainability consultants - thinkstep - confirm that emissions
from cement have been reduced by 15 percent between 2005 and 2018.
NATIONAL
reduction in CO2 reduction in CO2
from cement from concrete
PER CAPITA
reduction in CO2 from cement reduction in CO2 from concrete
PER UNIT (PER TONNE)
reduction in CO2 from cement reduction in CO2 from concrete
16 concrete VOLUME 61 ISSUE 1Your building
could be put to the
ultimate test.
So we do the same
to our steel.
At Pacific Steel, we put all our products through a rigorous testing
regime. Our dedicated laboratory has full IANZ certification and we’re
the only local manufacturer of reinforcing steel to have third party
ACRS certification. So when we say our SEISMIC® reinforcing steel is
tested to meet the AS/NZS 4671 standard, you can be sure it’s been
put to the ultimate test.
A steel bar about to be tested in one of five testing machines at our laboratory in Otahuhu.
PAC0015CCTHunter Expressway, NSW, Australia. Images: CCAA
A SUSTAINABLE CONCRETE
ROADMAP FOR THE FUTURE
CONCRETE ROAD PAVEMENTS ARE A COST-COMPETITIVE, DURABLE, SAFE AND
SUSTAINABLE ALTERNATIVE TO ASPHALT ROAD PAVEMENTS.
In New Zealand the case for concrete roads is As demonstrated by Infometrics in a recent
now more compelling than ever. update to The Case for Concrete Roads report,
the effect of these changes means that concrete
Waka Kotahi NZ Transport Agency (NZTA) has
roads are now potentially 29.4 percent less
adjusted its assessment criteria for future
expensive than asphalt alternatives.
roading projects to favour durable materials,
while at the same time evaluating the cause of Concrete roads typically have an extended
recent pavement failures on the Waikato and service life, during which they require minimal
Kapiti Expressways. maintenance. In contrast, asphalt roads demand
regular repairs, more so as vehicle loads and
Add to this, the fact that Government has made
volumes increase, interrupting traffic flow and
a commitment to huge infrastructure spending
compromising safety.
post-COVID-19 and to being zero carbon by
2050, and the scene is set for concrete roads to The greater price volatility of bitumen relative to
play a significant role in ensuring a resilient and cement / concrete further tilts the economics in
sustainable New Zealand. favour of concrete roads.
ECONOMIC ADVANTAGES SAFER ROADS
In early 2020 the NZTA increased the life cycle As asphalt roads require frequent maintenance,
of roading tenders to 40-years, and reduced they may exist in a sub-standard state for a
the discount rate (the time value preference of significant part of a 40-year life, which can impact
money) to 6 percent. on driver comfort and safety.
18 concrete VOLUME 61 ISSUE 1Concrete roads can be textured to provide skid carbon cement replacements such as fly ash,
resistance and quietness. They reflect high levels slag and natural pozzolans (pumice), improving
of light, especially street lighting, improving vehicle efficiency, and greater recycling and reuse
driver visibility. of concrete.
Another important safety consideration is that
CIRCULAR ECONOMY
as concrete roads require less maintenance, the
exposure of roading crews to traffic hazards At the end of their long service-life, concrete
is reduced. roads are recyclable. Once crushed, the concrete
can be re-used in a range of applications,
FUEL SAVINGS including as road base.
Concrete roads are ‘rigid’, preventing heavy This avoids having to dump end-of-life concrete
vehicles from deflecting the road surface and roading materials in landfills, meeting a
creating the ‘rolling resistance’ experienced with New Zealand government objective of waste
‘flexible’ asphalt roads. minimisation.
Research by the Massachusetts Institute of
Technology in the United States indicated that the CONCRETE ROADMAP
direct result is lower fuel costs per truck journey, As New Zealand moves forward, balancing the
which could total about 0.5 percent of transport need for economic stimulus post COVID-19 with
related emissions over 50 years - see pages 20-21. carbon zero aspirations, the benefits of concrete
will come to the fore.
LOWER CARBON FOOTPRINT
The Government’s infrastructure investment
The Cement Association of Canada1 commissioned
package is welcomed as a means to kick-start the
a study showing that the primary energy costs of
economy in the wake of the pandemic.
concrete roads over their lifetime are one-third
that of asphalt roads. It is an opportunity to future proof our bult
environment by taking advantage of concrete’s
The difference in New Zealand will be less
durability and cost-competitiveness.
pronounced with our renewable electricity.
However, this is still an important consideration, as At the same time, the concrete industry’s
is the fact that concrete absorbs atmospheric CO2 ongoing commitment to decarbonise, will play
over time, especially when crushed and recycled. an important role
There is also the albedo effect, which sees light- in ensuring New
coloured surfaces, such as concrete roads, reflect Zealand’s aim to be net
solar radiation back into space, resulting in less carbon zero by 2050
heat and in turn less global warming. remains achievable.
1. Athena Sustainable
Tenders for new roads are increasingly specifying Materials Institute for Cement
a lower carbon footprint in construction, up to 30 Association of Canada,
percent over a time period. Efforts the concrete A life cycle perspective
on concrete and asphalt
industry is making to reduce emissions will help in roadways: Embodied primary
this endeavour. energy and global warming
potential, Athena Sustainable
Measures include replacing a proportion of the Materials Institute for Cement
fossil fuels in cement kilns, introducing low- Association of Canada, 2006
VOLUME 61 ISSUE 1 concrete 19STIFFER ROADWAYS COULD
IMPROVE TRUCK FUEL EFFICIENCY
David L. Chandler | MIT News Office
STUDY FINDS SIMPLE CHANGES IN ROAD RESURFACING PRACTICES COULD IMPROVE
GAS MILEAGE FOR HEAVY VEHICLES AND REDUCE GREENHOUSE GAS EMISSIONS.
Every time you hear a deep rumble and feel your “When we as individuals walk on pavements,
house shake when a big truck roars by, that’s they seem like perfectly rigid things. They’re not
partly because the weight of heavy vehicles responding to us,” he says. “But for trucks, that
causes a slight deflection in the road surface is not the case. There is enough of a deflection
under them. It’s enough of a dip to make a in that surface that some amount of energy is
difference to the trucks’ overall fuel efficiency. expended to overcome the little divot that you
create as you drive along.” He likens it to the
Now, a theoretical study by MIT researchers
difference between walking on a hard surface
suggests that small changes in roadway
versus walking on sand, which takes more effort
paving practices could reduce that efficiency
because you sink in with each step.
loss, potentially eliminating a half-percent of
the total greenhouse gas emissions from the Looking to the future, Kirchain says that while
transportation sector, at little to no cost. projections show a slight decline in passenger
car travel over coming decades, they show an
The findings are detailed in a paper in the journal
increase in truck travel for freight delivery — the
Transportation Research Record, by MIT postdoc
kind where pavement deflection could be a factor
Hessam Azarijafari, research scientist Jeremy
in overall efficiency.
Gregory, and principal research scientist in the
Materials Research Laboratory Randolph Kirchain. There are several ways to make roadways stiffer,
The study examined state-by-state data on climate the researchers say. One way is to add a very
conditions, road lengths, materials properties, and small amount of synthetic fibers or carbon
road usage, and modeled different scenarios for nanotubes to the mix when laying asphalt. Just
pavement resurfacing practices. a tenth of a percent of the inexpensive material
could dramatically improve its stiffness, they
They found that that one key to improving
say. Another way of increasing rigidity is simply
mileage efficiency is to make pavements that are
to adjust the grading of the different sizes of
stiffer, Kirchain explains. That reduces the amount
aggregate used in the mix, to allow for a denser
of deflection, which reduces wear on the road but
overall mix with more rock and less binder.
also reduces the slightly uphill motion the vehicle
constantly has to make to rise out of its own “If there are high quality local materials available”
depression in the road. to use in the asphalt or concrete mix, “we can use
20 concrete VOLUME 61 ISSUE 1them to improve the stiffness, or we can just adjust considered the reductions that would be achieved
the grading of the aggregates that we are using by improving anywhere from 2 percent of road
for these pavements,” says Azarijafari. And adding surfaces to 10 percent each year.
different fibers is “very inexpensive compared to
the total cost of the mixture, but it can change the With a 10 percent improvement rate, they
stiffness properties of the mixture significantly.” calculated, a total of 440 megatons of carbon
dioxide-equivalent emissions would be avoided
Yet another way is to switch from asphalt
over the 50 years, which is about 0.5 percent of
pavement surfaces to concrete, which has a
total transportation-related emissions for this
higher initial cost but is more durable, leading
to equal or lower total lifecycle costs. Many road period.
surfaces in northern U.S. states already use The proposal may face some challenges, because
concrete, but asphalt is more prevalent in the changing the mix of materials in asphalt might
south. There, it makes even more of a difference, affect its workability in the field, perhaps requiring
because asphalt is especially subject to deflection
adjustments to the equipment used. “That change
in hot weather, whereas concrete surfaces are
in the field processing would have some cost to it
relatively unaffected by heat. Just upgrading the
as well,” Kirchain says.
road surfaces in Texas alone, the study showed,
could make a significant impact because of the But overall, implementing such changes could
state’s large network of asphalt roads and its in many cases be as simple as changing the
high temperatures. specifications required by state or local highway
Kirchain, who is co-director of MIT’s Concrete authorities. “These kinds of effects could be
Sustainability Hub, says that in carrying out this considered as part of the performance that’s
study, the team is “trying to understand what trying to be managed,” Kirchain says. “It largely
are some of the systemic environmental and would be a choice from the state’s perspective,
economic impacts that are associated with a that either fuel use or climate impact would
change to the use of concrete in particular in the be something that would be included in the
pavement system.”
management, as opposed to just the surface
Even though the effects of pavement deflection performance of the system.”
may seem tiny, he says, “when you take into
The research was supported through the
account the fact that the pavement is going to
be there, with thousands of cars driving over Concrete Sustainability Hub by the Portland
it every day, for dozens of years, so a small Cement Association and the Ready Mixed
effect on each one of those vehicles adds up Concrete Research and Education Foundation.
to a significant amount of emissions over the Reprinted with permission of MIT
years.” For purposes of this study, they looked News (http://news.mit.edu/)
at total emissions over the next 50 years and
VOLUME 61 ISSUE 1 concrete 21AGGREGATES’
CONTRIBUTION TO
THE SUSTAINABILITY OF
CONCRETE
James Mackechnie, Education, Training & Research Manager, Concrete NZ
THE SUSTAINABILITY OF CONCRETE MOSTLY FOCUSES ON THE CONTRIBUTION OF CEMENTITIOUS
BINDERS SINCE THESE MATERIALS HAVE HIGHER EMISSIONS AND ENERGY REQUIREMENTS.
Concrete aggregates are generally shown to have This assumption is not always true especially as
much lower embodied energy and carbon in concrete suppliers sometimes have to use more
comparison but this assumes optimum materials marginal deposits due to economic, logistic and/
that minimise binder contents in concrete without or environmental reasons.
compromising strength, dimensional stability and
When new concrete aggregates are being
durability. considered there are several performance
requirements that need to be considered.
Figure 1: Characterisation of concrete aggregates for use in structural concrete
22 concrete VOLUME 61 ISSUE 1Typical characterisation of aggregates properties slump tolerances but often affect strength and
for consideration in concrete are shown in yield of concrete supplied.
Figure 1. • Grading of aggregates needs to be consistent
to produce uniform workability and strength
FRESH CONCRETE PROPERTIES
of concrete. This is particularly important
The quality of aggregates has a direct effect on for fine aggregate where extra fines and silt
the fresh concrete properties and this in turn contamination can have a dramatic effect on
affects hardened properties such as strength and
water demand affecting not just workability but
dimensional stability.
also compressive strength.
Examples of this include the following: • Shape of aggregate particles is an important
• Variable moisture content of fine aggregate but often overlooked aspect of concrete
makes consistent concrete production more aggregates. Figure 2 shows how this affects
challenging, especially when not using moisture water demand and in turn increases cement
probes. These fluctuations may not just affect content and drying shrinkage of concrete.
Figure 2: Typical water demands used for structural concrete in New Zealand
VOLUME 61 ISSUE 1 concrete 23HARDENED CONCRETE PROPERTIES Pressure on quarries to deliver low-cost concrete
Some properties of concrete aggregates have aggregates often end up costing more for
a more obvious relationship with the hardened concrete since extra cementitious material is
properties of concrete such as density, strength required to compensate for sub-optimal fresh
and stiffness. and hardened properties of structural concrete.
While most aggregate sources have consistent Financial incentives need to be built into supply
strength, stiffness and dimensional stability this agreements that encourage optimum aggregate
cannot be assumed for all materials due to the properties such that moisture contents are
relatively young and diverse geology of New controlled, grading is consistent, aggregate shape
Zealand. is optimised and aggregate strength and stiffness
are monitored.
This is illustrated when the elastic modulus of
concrete made with different geological types is Experience in New Zealand has shown that when
compared as shown in Figure 3. concrete aggregates are optimised there is the
potential to reduce the cementitious content by
CONCRETE AGGREGATE QUALITY AND 15-20 percent compared with material that is
SUSTAINABILITY poorly produced.
When concrete suppliers view quarry resources This would benefit not just material costs of
there is sometimes the misconception that the concrete but also reduce emissions associated
cheapest materials produce the most cost- with Portland cement.
effective concrete.
Figure 3: Elastic modulus versus compressive strength at 28 days
24 concrete VOLUME 61 ISSUE 1Image: Quarry Magazine
PLAN FOR QUARRIES OR Wayne Scott
Chief Executive,
FACE MORE TRANSMISSION
AQA
GULLY DEBACLES
THE NATIONAL QUARRY ORGANISATION SAYS IT HOPES THAT THE DELAYS AND COST BLOW-
OUT FOR TRANSMISSION GULLY MAY FINALLY SEE A CHANGE IN GOVERNMENT AND COUNCIL
PLANNING FOR MAJOR PROJECTS.
Aggregate and Quarry Association Chief Executive Transmission Gully will be replicated around
Wayne Scott says Transmission Gully is only a the country.”
signal of what will happen unless the authorities
He says rock for the Wellington motorway project
address the need to plan for the quarries to
was in such short supply that some was trucked
supply major infrastructure initiatives, climate
from Mt Taranaki.
change mitigation, and affordable housing.
“You can imagine what a 600 km round trip added
“The Government has now asked the
to the cost.”
Infrastructure Commission to investigate why
Transmission Gully’s costs have gone through the The AQA has already shown the benefits of
roof and time delays mount. identifying local supplies of quarry material with
the Ōpōtiki wharf project. The estimated cost
“We’ve been telling this, and previous,
blew-out to $150M partly due to having to truck
Governments that they must put in place planning
rock nearly 100 km. The AQA worked with GNS
to provide for quarries. You cannot expect
Science to identify local sources of supply which
existing quarries with set caps on production to
contributed to a near halving of the wharf
meet the mega-requirements of a project of the
project cost.
scale of Transmission Gully.”
“While not the total answer, similar gains can
Wayne Scott says both major parties are
be made if we complete a national survey of
now promising a huge lift in infrastructure
rock resources which GNS has started but can’t
spend as a key policy to address COVID-19’s
complete for the sake of $600,000 in funding. If
economic impacts.
the Government is serious
“Unless we make the first step of a rapid about avoiding more
identification of available rock resource, we Transmission Gully events,
will find the delays and cost blow-outs of that’s where it should start.”
VOLUME 61 ISSUE 1 concrete 25RECAST FLOORS PROGRAMME ANALYSES PRECAST RETROFITS Iain MacIntyre A COMPREHENSIVE RESEARCH PROGRAMME IS UNDERWAY TO SCIENTIFICALLY VALIDATE AND, WHERE POSSIBLE, ENHANCE THE RETROFITTING TECHNIQUES USED TO IMPROVE THE PERFORMANCE OF PRECAST CONCRETE FLOORS IN MULTI-STOREY BUILDINGS, PARTICULARLY THOSE INSTALLED IN NEW ZEALAND PRIOR TO 2006. Concerns over the seismic vulnerability of such Engineering principal and ReCast Floors project floors – which feature extensively in the country’s manager Dr Nicholas Brooke says formal multi-storey building stock – surfaced after the validation was long overdue. 1994 Northridge earthquake in Los Angeles and have subsequently been borne out in local “The retrofit techniques being used in theory work seismic events. very well, but there might be unresolved issues With industry having progressively developed such as exactly how wide a piece of support steel retrofit techniques for affected buildings should be or whether it needs to be hard against based largely on “sound principles”, Compusoft an existing floor unit or set down slightly,” he says. 26 concrete VOLUME 61 ISSUE 1
Due to be completed by October 2021, the collaborative work is being directed by an eight-person research team.
“So some of it is validation of techniques streams of work.
that everyone expects to work, some of it is
One of those streams, laboratory and analytical
refinement of the methods of designing and
research, entails:
installing these techniques.”
• sub-assemblage testing of single units,
With a $2 million budget – funding provided by
BRANZ from the Building Research Levy, the • super-assemblage testing of multiple units
Earthquake Commission and a number of other supported by moment resisting frames; and
organisations – the ReCast Floors project formally • computer simulation by developing finite
commenced in October 2018. element analysis tools.
Due to be completed by October 2021, the The other stream revolves around the
collaborative work is being directed by an eight- interpretation of real-world performance, and
person research team, representing the key New comprises:
Zealand groups involved in precast floor research.
• processing of damage assessment data,
Driven by four full-time PhD students at the
• forensic analysis of case study buildings,
universities of Auckland and Canterbury, with
another to join soon, the project is also being • documentation of damage in buildings; and
guided by an industry advisory group consisting of • in-situ testing of precast concrete floors
other key stakeholder representatives. (dependent on opportunities).
Encompassing several different investigations Dr Brooke describes the super assemblage test
being undertaken at a number of facilities, being built specifically for the project at the
the project’s planned research is split into two University of Canterbury as “spectacular”.
VOLUME 61 ISSUE 1 concrete 27As well as seeking to validate existing retrofitting techniques, the project will test new and refine methods.
“It is basically a representation of a substantial “You hear ideas or suggestions that people are
part of a single floor in a building – something like contemplating but may not actually implemented
six columns with beams joining those together because they are uncertain about how that
and whole floor units spanning across.” approach might perform. A number of these
“That’s one of the larger test specimens that’s ideas are being fed into the research, developed
ever been put together in New Zealand. We’ll have further and be proven to be effective (or not) by
some really quite complex control systems to the ReCast Floors project.”
ensure the right parts go in the right directions at “In particular that could result in less-invasive
the right times.” solutions. A typical retrofit solution involves
At the time of being interviewed halfway through some relatively low-cost steel work to basically
the project, Dr Brooke says “many good findings” provide the load paths that aren’t reliably there.
are consistently being revealed. The cost of the structural parts would only be
something like 20 percent of the total, whereas
“For example, there were concerns that some
the disruption to the existing fit out would be the
of the retrofits already done could have actually
other 80 percent.”
made certain aspects of seismic behaviour worse.
However that, in most instances, now seems “So, there is a drive to look for retrofits that can
unlikely to be an issue.” either be done from underneath or above a floor
– but not both – as obviously, that gives you much
As well as seeking to validate existing retrofitting
less disruption.”
techniques, Dr Brooke emphasises the project will
test new and refine existing methods, potentially “One of the overarching goals of the project is
leading to the development of less-expensive for it to serve as the focal point for the collation
solutions. and investigation of issues related to precast
28 concrete VOLUME 61 ISSUE 1Overview of research projects, oversight arrangements and expected outputs.
concrete floors and the dissemination of findings analytical models of the hollowcore floors.
to industry,” says Dr Brooke.
“If that is successful, then it will basically allow
“At the time that the project was conceived consideration of a far wider range of floors than is
there was a concern that different organisations possible in a lab.”
seemed to be picking up different parts of the
Emphasising the “excellent job” being done
precast floor research – a lot of the same people
by all students involved, Dr Brooke says the
were involved. However, it was less an issue of
collaborative nature of the relationships forged
conflicting advice, more a risk of being inefficient.”
between the universities, industry and academics
“The project has succeeded in pulling everyone is a particular highlight of the project.
together under one roof and becoming the focal
“As far as I know it is probably the first time
point it was aimed to be.”
in structural engineering and, maybe more
Dr Brooke says another potentially “ground- generally, where a large programme of research is
breaking” aspect of the project is the work being being run at two universities in parallel, with day-
undertaken by one of the PhD students at the to-day collaboration.”
University of Canterbury to develop complex
IMPORTANT MESSAGE
An important message that Concrete NZ’s Technical Director Dave McGuigan hopes the ReCast
Floors project will deliver is that industry is prioritising the issue of life safety of buildings with
potentially vulnerable floor systems in a seismic event.
“The key output of this project is that it restores confidence amongst building owners and
practitioners that we are making sure the building stock achieves life safety objectives,” he says.
“The Canterbury and Kaikoura earthquake events demonstrated the vulnerability of these buildings
– in particular Statistics House in Wellington where three floor units lost their support.”
“While the focus is on addressing something that could have major life safety consequences people
still need to be mindful that these buildings will have performance characteristics that might
render them uneconomic to repair after an earthquake.”
VOLUME 61 ISSUE 1 concrete 29The upgrade was undertaken as the approximately 50-year-old reservoir was beginning to suffer durability issues and pose seismic resilience concerns.
UPGRADE GIVES RESERVOIR NEW
50-YEAR LEASE ON LIFE
A RANGE OF MARLBOROUGH DISTRICT COUNCIL STIPULATED OUTCOMES HAVE BEEN
SUCCESSFULLY DELIVERED IN A CHALLENGING PROJECT TO UPGRADE AND PROVISION FOR
ANOTHER 50 YEARS’ WORKING LIFE FOR THE WITHER HILLS (WELD STREET) RESERVOIR.
Rather than demolition and replacement, a The upgrade was undertaken as the
more sustainable approach involving upgrades approximately 50-year-old reservoir – which
and additions to the existing 36 metre diameter stores 5.3 million litres of unchlorinated, potable
prestressed concrete structure was adopted. water for Blenheim – was beginning to suffer
durability issues and pose seismic resilience
The construction had many challenges such as
concerns.
a tight programme, as-built details that differed
from the drawings, along with existing (and new) Amongst issues targeted for remedy in the
concrete issues. reservoir’s upgrade, which is a critical regional
These challenges were overcome through a water resource following earthquakes and for
collaborative and innovative problem-solving firefighting, were:
approach between Marlborough District Council, • Re-profiling design of the slope above the
CH2M Beca and Fulton Hogan. reservoir with a flatter angle to minimise the
30 concrete VOLUME 61 ISSUE 1potential impacts of slope failure or earthquake • Undertaking remedial work, including internal
debris on the facility. surface remediation of wall and columns, floor
• Placing a new reinforced concrete topping slab slab sealant replacement and crack injection of
to provide a roof diaphragm, which also sealed active leaks in the walls.
the reservoir contents from rainwater ingress. Other challenging aspects of the construction
• Installing external post-tensioning to phase included:
strengthen the roof tee beams for the
• Cutting a large access hatch into the roof
increased mass of the topping slab and to also
at the beginning of construction to provide
maximise reuse of the existing structure.
ventilation, lighting and access for scissor lifts
• Fitting a new reinforced concrete roof ring
and other large construction equipment. This
beam to allow for thermal movement of the
also meant the reservoir could be classed as a
roof while accommodating a seismic shear load
‘restricted space’ instead of a ‘confined space’
transfer from the roof to the walls.
due to alternative access/egress routes and
• Installing an internal reinforced concrete additional ventilation.
floor ring beam, with dowels cored through
the walls around the perimeter, connected • Staged external roof post-tensioning and roof
to the existing floor slab and foundation with topping slab pours to maintain stress limits
reinforcement starters to provide an enhanced in the existing roof tee beams. A survey was
seismic base shear transfer mechanism. carried out at each stage to monitor deflections
which were compared with predicted.
• Installing external wall post-tensioning to
compensate for a shortfall in the hoop tension • A unique roof topping slab pour shape and
capacity under Ultimate Limit State seismic sequencing of a series of concentric rings
loading, while also providing new active to achieve tight construction tolerances
hoop compression to the wall joints for leak and complement external roof beam post-
mitigation at the vertical construction joints. tensioning.
• Fitting new, larger-dimensioned stainless steel • Casting post-tensioning anchorage pockets into
pipework to provide additional flow capacity, the concrete using three dimensional printed
with a new chamber constructed to house inserts.
sensor-controlled seismic isolation valves.
VOLUME 61 ISSUE 1 concrete 31You can also read
