Laboratory investigation of the effect of warm mix asphalt (WMA) additives on the properties of WMA used in China

To investigate and compare the influence of various commonly used warm mix asphalt (WMA) additives on the physical, mechanical, and performance properties of WMA, a series of laboratory testing programs such as air void, voids in mineral aggregate, freeze-thaw splitting, wheel tracking test, and bending beam tests were performed. The experimental design of WMA mixtures included the use of three WMA additives of Sasobit, Evotherm and Rediset, two asphalt binders of SK-70 base asphalt, and a styrene-butadiene-styrene (SBS)-modified one. The testing results of WMA were also compared to that hot mix asphalt (HMA) as controls. Results from this study showed that: (1) volumetric properties (air voids and VMA) of WMAs did not have significant difference from the controls; (2) WMA with Sasobit had the greatest Marshall stability, followed by the WMA with Rediset, whereas all WMAs with Evotherm had the least, regardless of the types of asphalt; and (3) for WMA with modified asphalt, the dynamic stability of WMA with Rediset was a slightly greater than other two WMAs. For WMAs with base asphalt, the dynamic stability with Evotherm and Sasobit was similar to the control and greater than that with Rediset: (4) The WMAs with Sasobit have slightly greater indirect tensile strength (ITS) and tensile strength ratio (TSR) than the other two, regardless of the types of asphalt. (5) WMAs with Rediset had the greatest bending failure strain, regardless of the types of asphalt. Among all asphalt mixtures, most of WMAs had lower bending failure strain than the controls.