Comparing the Effects of Coal Waste Filler and Pozzolanic Fillers on the Mechanical Properties of Hot Mix Asphalt

Due to the limitation of natural resources and road construction developments, the demand for using waste and recycled materials has significantly increased. Coal waste is a by-product of the coal washing plant and its accumulation leads to different environmental and economic complications. The main objective of the current paper is to compare using coal waste powder and ash as filler in hot mix asphalt with other usual pozzolanic fillers. In the first section of this study coal waste completely replaces the usual fillers with lime stone powder and is compared with the pozzolanic fillers such as cement and zeolite. Mechanical properties studied here include Marshall Stability, Marshall Quotient, flow, tensile strength and moisture sensitivity. In the second section in order to better explore the subject, besides the above-mentioned mechanical properties, the resilient modulus and the fatigue of samples containing coal waste and ash a reanalyzed. The test results from the first section show that using coal waste filler improves the mentioned mechanical properties compared to lime stone powder and zeolite. Moreover, in the second section while coal ash has a better result compared to the raw state but due to difficult procedure, high cost and the pollution resulted from burning, using raw coal waste as filler in hot mix asphalt is recommended.