This investigation was for a 28 km stretch of Newell Highway that is a single lane in each direction. It has the highest heavy vehicle traffic in NSW and is an annual flood risk.
Foamed bitumen is a mixture of air, water and bitumen. Once a foaming agent is mixed, it expands about 15 times, it has a large surface area and low viscosity. When mixed with gravel material, the droplets coat the finer particles that binds them together.