Low carbon recycled sustainable asphalt - myth or reality?

Abstract

Asphalt is the most popular material used to surface roads in built environments. However, Australia consumes 10 million tonnes of non-renewable materials to produce this asphalt which is also responsible for generating 800,000 tonnes of CO2e per annum. With society demanding a reduction in the generation of greenhouse gases to combat global warming, this presentation looks at the pathways and the barriers to reducing 1) the carbon footprint of asphalt and 2) the demand for the non-renewable raw materials to manufacture asphalt.

Traditionally asphalt is produced from non-renewable raw materials and consumes energy to heat the bitumen and dry the aggregates during manufacture. Asphalt can be made more sustainable by: • Replacing these non-renewable materials with repurposed waste materials. • Reducing the temperature required to produce asphalt. • Improving the asphalt performance properties to increase its service life.

By using the AfPA carbon calculator we can determine the cradle to gate carbon footprint of each mix type at a particular plant. The presentation will show case the production and performance of low carbon dense graded asphalt against AC14HD and AC20HD mixes conforming to TfNSW specification R116 by looking at the following pathways, namely: • using repurposed waste materials with a proven track record of use in asphalt • replacing hydrated lime with a chemical liquid antistrip agent • lowering asphalt mixing temperatures • using alternative heating fuels • using biogenic binders

We will discuss barriers to utilising the above pathways from an economic, legislative and environmental perspective. This will be supported by industry experience in producing and paving high performance low carbon asphalt at Colas’s Newcastle asphalt on local Council roads.