防渗层水工沥青混凝土低温柔性影响因素分析

Analysis of Factors Affecting Low-temperature Flexibility of Hydraulic Asphalt Concrete of Impervious Layer

为了分析防渗层水工沥青混凝土低温柔性及其影响因素,开展了不同沥青品种、沥青用量和骨料级配的低温小梁弯曲试验,采用弯曲应变和弯曲应 变能密度分析了不同沥青混凝土的低温柔性。试验结果表明,沥青品种对弯曲 应变影响最大,其次为沥青用量,骨料级配影响最小。SBS改性水工沥青混凝土 的低温柔性远优于普通石油水工沥青,沥青用量增大可明显提高低温柔性,而级 配指数越小,越有利于改善低温性能。与最大弯拉应变相比,弯曲应变能密度临 界值从能量断裂角度出发,综合了弯拉应变和抗弯拉强度两个指标,能更好地反 映沥青混凝土的低温柔性以便于进一步优化配合比设计。

The low-temperature flexibility of hydraulic asphalt concrete of the impermeable layer and its influencing factors are investigated.Three-point bending tests are carried out by taking into account different types of asphalt,asphalt contents and aggregate gradations.The bending strain and bending strain energy density are used to analyze the low-temperature flexibility of various types of asphalt concrete.The test results show that the type of asphalt has the greatest influence on the bending strain,followed by asphalt contentand aggregate gradation.The low-temperature flexibility of SBS modified hydraulic asphalt concrete is far better than that of petroleum hydraulic asphalt.Increased asphalt content can significantly improve the flexibility.Lower gradation index can result in better performance.Compared with the maximum flexural strain,the critical value of flexural strain energy density is based on the energy fracture point of view.It combines flexural tensile strain and strength and thus well reflects the low-temperature flexibility of asphalt concrete,which is helpful for the further optimization on mix design.