Application Of Recycled Cement Mortar Powder In Asphalt Mixture

A lot of waste concrete is generated in the process of building construction or demolition, forming the main components of construction waste. The most effective way to reuse waste concrete is to prepare recycled aggregates, but a lot of recycled cement mortar powder is also generated in this process. At home and abroad research on and application of recycled cement mortar powder is still not carried out. In this paper, the performance of recycled cement mortar powder, the performance of asphalt mastic with recycled cement mortar powder and the performance of asphalt mixture with recycled cement mortar powder were studied and compared with the traditional limestone filler. Feasibility of the application of recycled cement mortar powder in asphalt mixture was explored to expand reusing ways and improve its efficiency.Compared with limestone filler, recycled cement mortar powder has slightly larger size, smaller density, higher hydrophilic factor, but they could meet requires of Chinese specifications about filler used in asphalt mixture. From the chemical composition point of view, for the reason of existence of hydrated cement paste and non-hydrated cement paste, cement mortar powder contains both carbonate and silicate compounds of Ca and various compounds of Al, Fe, K and Mg. From the microstructure point of view, the surface of cement mortar powder is bulky and full of floe attachment.Compared with asphalt mastic with limestone filler, asphalt mastic with recycled cement mortar powder has decreased penetration, penetration index and plastic temperature range and increased equivalent softening point, equivalent crisp point, indicating the higher temperature sensitivity, improved high temperature stability and relatively poor low temperature cracking resistance of asphalt mastic with recycled cement mortar powder. The ductility of asphalt mastic with recycled cement mortar powder at 5℃and 15℃was slightly lower than the asphalt mastic with limestone filler, but its softening point and viscosity was higher, indicating the flexibility of asphalt mastic with recycled cement mortar powder is relatively poor but its resistance to high temperature deformation is improved. And the mixing temperature and compaction temperature of asphalt mastic with recycled cement mortar powder are respectively increased by about 5℃,10℃.Compared with asphalt mixture with limestone filler, asphalt mixture with recycled cement mortar powder has higher dynamic stability, smaller creep strain, higher creep stiffness modulus, and relatively small low temperature flexural strength of the damage, the maximum bending strain, bending stiffness modulus, indicating the good resistance to high temperature deformation, and relatively poor resistance to low temperature cracking of asphalt mixture with recycled cement mortar powder. And the results of asphalt mastic tests coincide. The Marshall Stability, residual Marshall Stability and TSR values of asphalt mixture with recycled cement mortar powder are relatively high, indicating the good moisture stability of asphalt mixture with recycled cement mortar powder. Combination of high and low temperature performance point of view, recycled asphalt cement powder is suitable to be used in hot and humid areas.