Study on the Rheological Properties of Fly Ash Modified Asphalt Mastics

Fly ash is one of the industrial waste residues with significant emissions in China, and its rational utilization has important economic significance and environmental value. Due to the similarity in properties between fly ash and limestone mineral powder, it is possible to replace the mineral powder filler in asphalt concrete with fly ash. This article explored the feasibility of replacing the mineral powder with fly ash in an asphalt mixture through the study of fly-ash-modified asphalt mastic. Firstly, the microstructures and elemental compositions of fly ash and mineral powder were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Then, the rheological properties of asphalt mastics with different fillers were studied using dynamic shear rheological (DSR) tests. The results show that when the stress level was 3.2 kPa, the change in the Jnr value was different from that at 0.1 kPa, indicating that after increasing the stress level, the Jnr of fly ash asphalt mastic was smaller, and fly ash can improve the high-temperature creep performance of asphalt mastic. Replacing mineral powder with fly ash can improve the high-temperature rheological properties of asphalt mastic, but this damages the elastic and crack resistance properties of the asphalt mastic. In practical applications, partial substitution of mineral powder can be considered for the preparation of an asphalt mixture.