Abstract: In order to provide a scientific basis for the promotion and application of steel slag powder and coal gangue powder in asphalt mixtures,high-temperature rutting,water immersion Marshall,freeze-thaw splitting,and low-temperature bending tests were conducted to investigate the effects of different addition dosage (0%,25%,50%,75%,100%) of steel slag powder and coal gangue powder on the performance of SMA-13 asphalt mixtures,and SEM and XRD analyses were used to reveal the strength formation mechanisms. The results indicated that the physical and mechanical properties of the asphalt mixture (void ratio,stability,flow value) all show an upward trend with increasing steel slag powder and coal gangue powder content; As the content of steel slag powder and coal gangue powder increases,the high-temperature stability of SMA-13 asphalt mixture first improves and then slightly decreases. When the content reaches 75%,the high-temperature stability is optimal,with the dynamic stability improving by 25. 7 percentage points;Increasing the content of coal gangue powder or steel slag powder in the mixture gradually improves the water stability of SMA-13 asphalt mixture,but the low-temperature crack resistance slightly decreases;At a 100% content,the residual stability and residual strength ratios of the asphalt mixture increased by approximately 4. 5 percentage points and 5. 5 percentage points,respectively,while the maximum failure strain decreased from 2 861 με to 2 721 με,but still met the current standard requirement of failure strain ≥2 000 με. Microscopic characterization confirms that the improvement in mixture performance attributed to steel slag / coal gangue powder stems from its unique microscopic morphology,active chemical components,and optimized mineral composition. These factors collectively enhance the bonding performance at the asphalt-aggregate interface and the overall mechanical strength of the mixture. 

Key words: asphalt mixture,steel slag powder,gangue powder,high temperature stability,water stability,low temperature cracking resistance