Concrete steps on climate change

Whanganui District Council has been working with its Roading Alliance partner Downer on a climate change initiative to reduce and reuse waste concrete.

Downer maintains the roading and pedestrian network in urban Whanganui and the wider district. A considerable amount of concrete and asphalt waste material is produced when repairs and improvements are made to the network.

The council’s senior roading engineer, Brent Holmes, says, “To reduce disused roading material going to landfill, the Roading Alliance decided to trial using concrete waste as a product that could be used for unsealed road remetalling.”

The potential reuse of local concrete waste was seen as an alternative to using 100 percent new material sourced as greywacke from Kakariki in Rangitikei and limestone shellrock from Maxwell.

Brent Holmes says, “Together with Downer, we grew a stockpile of concrete waste to an economic size and a subcontractor was engaged to crush the concrete into a suitable grading aggregate. This material was then placed on sections of our district’s unsealed rural roading network to see how it performed.” “We found these products are actually better in some situations than the materials we’ve traditionally used. The crushed concrete product also generates less dust than traditional materials, which is a real bonus to our rural communities in hot, dry conditions.”

To continue from the trial success, the Roading Alliance is now accepting some commercial concrete waste to grow the stockpile of reusable material faster. This will have the advantage of further reducing costs as well as possibly improving the performance of the crushed concrete product. Read more at: www.whanganui.govt.nz/concrete-waste