Experimental Research On Performances Of Granite Asphalt Mixture For Thin Overlay

With the over-exploitation of high-quality road materials, such as basalt, limestone, etc. The hard and stable granite has gradually become the hotspot of research and usage. But the cohesive (or bonding) performance between granite and asphalt is poor, and the water stability of the asphalt mixture is bad, so it was seldom used on the surface. Therefore, the experimental research on performances of granite asphalt mixture for thin overlay was conducted, based on the asphalt pavement preventive maintenance project in the Foshan First Ring Road.1) Through the performance test of raw materials, the granite showed good abrasive resistance preformance, so it can be used on the surface of asphalt pavement. Modified asphalt, containing0.3%ASA-9304type of anti-stripping agent, showed good thermal storage stability and thermal stability, and the viscosity and stripping resistance between granite and asphalt were significantly improved.2) Through mix proportion design, the mix proportion of TOAC-13granite asphalt mixture with graded porosity of12%,15%and18%were determined respectively. The anti-stripping agent and slaked lime were added respectively to improve the viscosity of three graded mixtures mentioned above. According to the results, after adding anti-stripping agent and slaked lime, the loss of flying decreased by32.3%～36.8%and15.3%～25.8%, and analysis leakage quantity,42.9%～46.2%and76.9%～85.7%, respectively. It can also improve the stripping resistance of asphalt mixture significantly, and has a positive effect on extending lifespan of the drainage type granite asphalt mixture for thin overlay.3) Three graded mixtures show good road performance in the pavement performance test, and meet the requirements of specification after adding. Although The MS0and TSR of the granite asphalt mixture without anti-stripping agent and slaked lime were less than80%, these indexs can improved to meet the requirements of specification by adding anti-stripping agent and slacked lime,and the freeze-thaw splitting test showed good anti-aging performance of ASA-9304anti-stripping agent. Anti-stripping agent’s effect on DS value was weak, and slaked lime can improve DS value by11%. To conclude, the second graded mixture TOAC-13adding anti-stripping agent is the best mix proportion for the preventive maintenance projectin the Foshan First Ring Road.4) Through the in-door test and related technical specifications of granite asphalt mixture for thin overlay, referring to some successful construction experience, key construction technology techniques, quality control and acceptance criteria for granite Synchronous thin overlay, was brought up.