Study on flexural properties of coal gangue powder asphalt mixture under freeze-thaw cycles

Abstract

In order to study the influence of freeze-thaw cycle on the flexural performance of asphalt pavement, semi-circular flexural test (SCB) is carried out. Coal gangue powder (accounting for 0%, 25%, 50%, 75% and 100% by weight of ore powder) is used to replace ore powder to improve the freeze-thaw resistance of asphalt.According to the test data, the load-displacement curve is drawn, the ultimate tensile stress( ${\sigma }_{t}$ ) is studied, and the variation law of different coal gangue powder replacement rates under different freeze-thaw cycles (0, 2, 4, and 6 times) is analyzed by ultimate tensile stress. The test results show that the best replacement rate of coal gangue powder is 50%, and ${\sigma }_{t}$ decreases with the increase of freeze-thaw cycles, so adding coal gangue powder can reduce the influence of freeze-thaw cycles on the bending performance of asphalt pavement. By analyzing the load-displacement curve, energy indexes such as W _D (total work from initial failure to complete failure), W _U (energy dissipation from initial failure to complete failure), W _S (work from initial failure to specimen failure) and ${\rm{\eta }}$ are obtained. In the freeze-thaw cycle, with the increase of cycle times, the energy consumption of W _D , W _U and W _S decreases, which aggravates the damage of asphalt mixture and reduces the flexural capacity of specimens. Among them, six freeze-thaw cycles have the lowest flexural capacity of specimens, indicating that freeze-thaw damage directly affects the flexural performance of asphalt mixture.

Keywords

• freeze-thaw
• coal gangue powder
• damage mechanism
• energy indexes