不同空隙率排水性沥青混合料宏观性能与微细观空隙结构研究

为了兼顾排水性沥青混合料排水性能与耐久性能,在JTG F40-2004推荐的OGFC-13矿料级配范围内选取5种级配,使得5种级配排水性沥青混合料空隙率为18%~24%,针对室内试验试验研究不同空隙率排水性沥青混合料力学性能、路用性能、疲劳性能,基于X-Ray CT的无损检测技术获取排水性沥青混合料内部的细微观空隙形态,采用平均空隙直径、空隙级配未评价指标,研究不同级配排水性沥青混合料的微观空隙分布特征,最后建立排水性沥青混合料细微观空隙结构与其宏观路用性能之间的关系。结果表明,9.5、4.75、2.36 mm这3种筛孔通过百分率与空隙率的相关性最好;在20%~21%空隙率时排水性沥青混合料的动稳定度达到峰值,抗弯拉强度、弯曲应变、浸水马歇残留稳定度、冻融劈裂强度比及各应力水平下的疲劳寿命随着空隙率增大而减小;排水性沥青混合料空隙体积测算的平均空隙直径为6.8~10.3 mm,表面积测算的平均空隙直径为8.8~13.4 mm,直径大于4 mm的空隙数量占总空隙数量的75%以上。建议排水性沥青混合料适宜的空隙率为20%~22%。

Study on Macroscopic Properties and Microscopic Viscosity Structure of Drainage Asphalt Mixtures with Different Voids

In order to balance the drainage performance and durability of the drainage asphalt mixture,five gradations are selected within the JGF F40-2004 recommended OGFC-13 mineral grading range,so that the five grading drainage asphalt mixture void 18%~24%,based on laboratory tests to study the mechanical properties,road performance and fatigue properties of different void ratio drainage asphalt mixtures,based on X-Ray CT nondestructive testing technology to obtain the fine microscopic void morphology inside the drainage asphalt mixture The average void diameter and void gradation unevaluated index were used to study the microscopic void distribution characteristics of different graded drainage asphalt mixtures.Finally,the relationship between the fine microscopic void structure of the drainage asphalt mixture and its macroscopic road performance was established.The results show that the correlation between the percentage of 9.5,4.75 and 2.36 mm passes is the best.The dynamic stability of drainage asphalt mixture peaks at 20%~21% void ratio.The strength,bending strain,immersion Marsh residual stability,freeze-thaw splitting strength ratio and fatigue life at each stress level decrease with increasing void ratio;the average void diameter measured by the void volume of the drainage asphalt mixture is 6.8~10.3 mm,the average void diameter measured by the surface area is 8.8~13.4 mm,and the number of voids larger than 4mm is more than 75% of the total gap.It is recommended that the suitable void ratio of the drainage asphalt mixture is 20% to 22%.