Study on Pavement Performance of Recycled Asphalt Mixture Modified by Carbon Nanotubes and Waste Engine Oil

The large amount of recycled asphalt pavement mixture (RAP) generated during renovations has a negative impact on the environment. In recent years, how to rationally recycle and reuse RAP has become a hot research direction in the field of highway construction. However, the recycled asphalt binder has some problems such as instability, easy aging and decreased adhesion. In this paper, carbon nanotubes and waste engine oil were used to modify recycled asphalt binder. Through a high-temperature rutting test, low-temperature bending test and Marshall stability test, the properties of an asphalt mixture with 40% RAP modified by carbon nanotubes and waste engine oil, an asphalt mixture with 40% RAP and an asphalt mixture without RAP were compared and analyzed. The tests showed that 1.5 wt% carbon nanotubes could improve the performance of the old asphalt binder most significantly. After adding 1.5 wt% carbon nanotubes, the high-temperature rutting resistance of the asphalt mixture was increased by 24.3%, and the bending stiffness modulus and the best crack resistance at low temperature increased significantly. In addition, after adding 1.5 wt% carbon nanotubes, the Marshall stability of the waste-engine-oil-modified RAP could be restored to the level of the new asphalt mixture. In summary, carbon nanotubes can improve the high-temperature stability, low-temperature crack resistance and Marshall stability of waste-engine-oil-modified RAP.