Bitumen pavement suffers from moisture damage mainly due to loss of durability and stability in a short span of service life. Filler is known to be capable of increasing the stiffness of bitumen binder, contributing to improvement of moisture sensitivity of bitumen mixture. In this paper a new type of filler named 'Compound Fly Ash Modifier' (CFAM) was introduced in order to enhance the bond strength between acidic aggregate with bitumen. The primary object is to determine the effect of CFAM on the moisture sensitivity of bitumen mixtures prepared by gneiss and granite respectively, which are termed acidic aggregate. Modified Lottman test and fatigue test were conducted. The results show that CFAM improves the resistance of mixes to moisture damage in the increase in indirect tensile strength and the extension of fatigue life. Finally the mechanism of modified effects for CFAM is discussed.
