Early age volume change of cement asphalt mortar in the presence of aluminum powder

Cement asphalt mortar (CA mortar) is a highly flowable grouting material used in the slab track structure. CA mortar is required to possess a volume expansion rate of 1.0-3.0% after 24 h to guarantee a desired filling effect. This is achieved by the incorporation of aluminum powder (AP). The article investigates the volume change of CA mortar under various AP dosages, temperatures and asphalt emulsion/cement ratio (A/C). Results indicate that when AP is absent, volume shrinkage of 1.8-3.0% is noted at temperatures of 10-30A degrees C; upon the addition of 0.013-0.021% AP, CA mortar undergoes slight volume shrinkage before 4 h, and then keeps expanding until about 24 h after which volume expansion slows down gradually; the expansion rate of CA mortar is greater, the lower the temperature is, and also the higher A/C is.