富沥青混合料设计方法的改进

Improvement of FAC Designing Method

分析了富沥青混合料设计方法(主骨架空隙填充法)存在的问题及其原因,并采取措施加以改进。首先,通过推导混合料体积平衡方程,找出了实测空隙率与设计目标空隙率存在差异的原因,引入干涉系数α,改进原设计方法,从而有效消除了空隙率的差异;其次,在混合料的体积平衡方程中引进参数Vbe,实现了对VMA的控制;最后,通过马歇尔试验、浸水马歇尔试验、冻融劈裂试验、低温小梁弯曲试验等证明了改进的主骨架空隙填充法的优越性。结果表明,用改进的主骨架空隙填充法设计出的富沥青混合料的体积指标、水稳定性、高温和低温性能均满足《公路沥青路面施工规范》的要求。改进的主骨架空隙填充法可广泛应用于设计FAC、SMA等密断级配的沥青混合料。

Improvement measures for some key problems of FAC designing method （CAVF method） are undertaken.Firstly, reasons of deference between actual-W and goal-W are analyzed by inferring mixtures vohune balance equation. The former designing method is improved by introducing the interference coefficient α. Secondly, introducing Vbe to volume balance equation made VMA in control. Finally, Marshal testing, soggy Marshal testing, freezing-melting testing and rut testing proved that improved CAVF method is a reasonable one for FAC designing. The results indicate that properties of designed FAC by improved CAVF method meet technical specifications for construction of highway asphalt pavement. Consequently, this method is recommendable to design FAC, SMA and other close-discontinuous gradation asphalt mixtures.