Lowering emissions through warm mix asphalt

On the Ovingham Level Crossing Removal Project in Adelaide our team expanded the use of Warm Mix Ashphalt (WMA) and combined it with Recycled Asphalt Pavement (RAP) to drive down emissions. 

Asphalt is a major material used on road projects and replacing Hot Mix Asphalt (HMA) (typically 175°C); with WMA (typically 140°C) is a generally accepted practice. However current asphalt specifications only allow for placement when the surface temperature is above 20°C, thereby limiting its use.

To overcome this restriction our team developed an alternative placement method allowing the WMA to be laid below 20°C. The first layer is the standard HMA and the following layers are WMA.

Not stopping there, our team combined the use of WMA with a 10% Recycled Asphalt Pavement (RAP) content in the wearing and levelling courses, and a 30% RAP content in other layers. 

This approach has led to an estimated 10% to 15% reduction in the overall emissions associated with asphalt use on the project. 

Based on this positive experience Warm Mix Asphalt has now been used on other McConnell Dowell projects.