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Tauranga Harbour Link 2 "Mix M"

05 Sep 2010

A special concrete mix designed by the Fletcher Construction Company, Firth Industries and Golden Bay Cement for the Tauranga Harbour Link project won the 2010 Supreme Concrete³ Sustainability Award, as well as the Excellence in Civil Concrete Construction Award.

Designated “Mix M”, the concrete mix was formulated to produce concrete capable of surviving 100 years in harsh marine conditions, and was employed extensively in Stage 2 of the Tauranga Harbour Link project to form beams used in the off-ramps, bridges and land spans.

Mix M achieved top honours in concrete sustainability for its specially blended and extensively trialled mix of Golden Bay Cement, fly ash (a waste product from coal burnt at Huntly Power Station), and microsilica 600, which together enabled durability, high early strength, and high workability requirements to be met. The use of fly ash and microsilica also resulted in a significant reduction in cement requirements and a corresponding reduction in the carbon footprint of the concrete beams.

Mix M represents a significant step forward in concrete mix design and durability modelling, one which combined enhanced environmental credentials with superior performance. Not only was the mix design sophisticated in optimising cement replacement, but by sourcing fly ash from within New Zealand, and using microsilica slurry rather than the more energy intensive powder, Mix M scored additional sustainability points.

In terms of construction practice, a dedicated concrete production plant was set-up on site helping to minimise delivery distances, fuel emissions, as well as reduce local traffic disruption. The closeness of the plant to site also enabled leaner production and less waste due to enhanced communication between placing and concrete production teams. Extensive use of self-compacting eliminated vibration and associated noise, to provide a better working environment for the placing team, and protect local residents from noise pollution.

“It was great for Fletcher Construction to be able to work with Firth and Golden Bay Cement to develop a product that ticked all the sustainability boxes as well as being a real construction solution. Winning the award was a really great endorsement of this combined team effort.”

Stuart Chapman, Environment Health and Safety Manager, Fletcher Construction Company


Graham Frost and Paul Gurran accept the 2011 Supreme Concrete3 Sustainability Award on behalf of the Fletcher Construction Company from CCANZ CEO Rob Gaimster