Pavement Performance of Coal Gangue Sand-Asphalt Mixture

Coal gangue is applicable to roadbed filling and base course of road engineering after breaking up, thus producing a large number of coal gangue sand.The in-situ stacking mode has caused serious damage to the ecological environment because it occupies extensive land resources.Reasonable disposal of coal gangue sand has important significance to the ecological environment.ATB-25 gradation was adopted to discuss the pavement performance of asphalt mixture prepared by replacing machine-made sand completely with coal gangue sand.Five test groups of non-mixture, fullmixture, full-mixture + 0.3% anti-rut agent, full-mixture + 0.4% anti-rut agent, and full-mixture + 0.5% anti-rut agent were designed.The Marshall stability test, Marshall residual stability test, freeze-thaw splitting test, and high-temperature rutting test under 60 were carried out.The effects of fine aggregate type and anti-rut agent content on the pavement performance of asphalt mixture were studied.The action mechanism of anti-rut agent on the coal gangue sand-asphalt mixture (CGS) was analyzed in combination with pavement performance test results.According to test results, the fine aggregate type can influence the performance of asphalt mixture, and the optimal asphalt content (OAC) of the CGS is increased significantly.The Marshall stability (MS) increases from 7.80 kN to 8.87 kN.After the machine-made sand is completely replaced by gangue sand, the water damage resistance and high-temperature deformation resistance of asphalt mixture decline significantly.With the increase in anti-rut agent content, the high-temperature deformation resistance of asphalt mixture increases gradually, but the water damage resistance of the mixture is not improved effectively.When the anti-rut agent content is 0.3%, the water stability of the asphalt mixture is damaged the least while assuring hightemperature stability.After mixing with the anti-rut agent, fine aggregates in the mixture will form group particles centered at anti-rut agent particles, which increases the interlocking forces among mineral aggregates, thus improving the high-temperature stability of the mixture.The research results will provide theoretical reference to application of CGS in road engineering.