为推广中性骨料在西部严寒地区沥青混凝土面板中的应用,采用中性骨料辉绿岩进行室内沥青混凝土面板防渗层配合比和性能试验研究,通过13组试件对不同配合比沥青混凝土的孔隙率、48 h马歇尔斜坡流淌值、劈裂抗拉强度和劈裂破坏拉伸应变等指标进行分析,提出优选配合比,即级配指数0.4、沥青含量7%、填料掺量12%。性能试验研究验证得到:辉绿岩骨料黏结力等级为5级;优选配合比下沥青混凝土防渗层各项性能指标均能满足规范要求,具有足够的防渗性和变形能力;同时其冻断温度低于-37 ℃,能抵抗当地最低-31.9 ℃的低温环境要求。

[Objective] Asphalt concrete is widely favored as an impermeable panel in pumped-storage power station design due to its excellent impermeability, deformation adaptability, self-healing ability, and ease of construction. At present, research on the application of neutral aggregates in asphalt concrete panels is limited, especially regarding experimental results on their key performance. This paper aims to promote the application of neutral aggregates in asphalt concrete panels in severe cold regions of western China. [Methods] Laboratory mix design and performance tests of asphalt concrete panels were carried out using neutral aggregate diabase. Thirteen groups of specimens were prepared to analyze porosity, 48 h Marshall flow value, splitting tensile strength, and splitting failure strain of asphalt concrete with different mix proportions. The optimal mix proportion was proposed as: gradation index 0.4, asphalt content 7%, and filler content 12%. To verify the adhesion between diabase coarse aggregate particles and asphalt, the boiling test was conducted. [Results] After 5 minutes of boiling, the asphalt film coating on the surface of diabase coarse aggregate particles was completely preserved, with the percentage of stripped area approaching zero and an adhesion level of Ⅴ. To compare the performance differences between neutral and alkaline aggregate asphalt concrete, comparative performance tests were conducted on asphalt concrete with diabase and limestone aggregates. The results showed that asphalt concrete with diabase aggregate exhibited better slope flow value and maximum flexural strain than that with limestone aggregate, while other mechanical and deformation properties showed no significant difference. [Conclusions] Under the recommended mix proportions, the permeability coefficient, water stability, slope flow value, splitting test, small beam bending test, direct tensile test, and bonding strength with cement concrete of the diabase aggregate asphalt concrete impermeable layer all meet the relevant technical requirements for asphalt concrete face dams. The freezing temperature of the recommended asphalt concrete mix is lower than -37 ℃, enabling it to withstand the local minimum temperature of -31.9 ℃ and satisfy design specifications. Based on the results of the static triaxial test, the Duncan-Chang model parameters of the asphalt concrete impermeable layer material with the recommended mix proportion are obtained, which can be applied to numerical calculations of dam stress-strain.