Impacts of water content on rheological properties and performance-related behaviors of foamed warm-mix asphalt

It has been shown from existing studies that foamed Warm Mix Asphalt (WMA) can effectively improve the workability of asphalt mixtures at relatively low temperature. However, there is limited research into the influence of the amount of water used to foam WMA on the rheological properties and performance-related characteristics of the foamed asphalt. In this study, different amount of water was used to foam non-modified and styrene-butadiene-styrene triblock copolymer (SBS) modified bitumen to create foamed bitumen specimens. They were subsequently tested for high temperature performance, low temperature performance, temperature sensitivity, and fatigue resistance properties. Test results indicate that water content in the foamed asphalt has significant impacts on its various properties and there is an interactive effect between asphalt type and water content. In general, it appears that better results can be achieved if one per cent of water is used to foam the unmodified asphalt, and three per cent of water is used to foam the modified asphalt. The findings may assist controlling experimental variations and improving foamed WMA production.