Use of rice husk ash-activated fillers on rutting and moisture resistance of cold mix asphalt

Cold mix asphalt (CMA) is an eco-friendly alternative to the conventional hot mix asphalt in road construction. This study investigates the potential of rice husk ash (RHA) as an activator with fly ash or ground granulated blast furnace slag (GGBS) to improve the performance of CMA in terms of rutting and moisture resistance. Indirect tensile strength and wheel tracking tests were used to assess the mechanical strength, and retained Marshall stability test was used to evaluate the moisture resistance of CMA with different non-conventional fillers. Rutting resistance of CMA was also assessed by multiple stress creep recovery test on emulsified asphalt-filler mastic using a dynamic shear rheometer. All the non-conventional fillers showed a specific impact on each of the investigated properties. The improvement is due to the formation of hydration products in the CMA, as confirmed through the XRD analysis of the mastic. RHA was found suitable for being used as an activator with fly ash or GGBS. Cold mix asphalt containing mineral filler and GGBS with RHA as an activator offered superior performance in all the indicators considered.