旧料对沥青混合料力学特性的影响

Influence of RAP on Mechanical Property of Asphalt Mixture

为了更精细地分析旧料对沥青混合料性能的影响,将旧料采用4.75 mm的筛网热筛分为粗、细两个部分,通过掺加不同比例的粗、细旧料组成6种级配的沥青混合料进行间接拉伸模量试验和劈裂强度试验,采用不同荷载频率的间接拉伸劲度模量、冻融前后的劈裂强度、破坏应变、黏韧性指数等指标评价了旧料对沥青混合料力学特性的影响。研究表明:低频率下的劲度模量、黏韧性指标、冻融前后的劈裂强度比可以作为掺加旧料沥青混合料力学特性的评价指标;旧料中与沥青混合料力学特性存在相关性的主要是旧沥青含量,旧沥青含量越高,沥青混合料拉伸劲度模量越大,黏韧性指数越小,冻融前后的劈裂强度比越小,力学特性越差。

To analysis the influence of reclaimed asphalt pavement （RAP） on the performance of asphalt mixture more accurately, the RAP is divided into coarse part and fine part by using 4.75 mm sieve. Six gradations of asphalt mixture are composed by different dosages of coarse part and fine part RAP to canied out indirect tensile modulus test and split strength test. The influence of RAP on the mechanistic performance of asphalt mixture are evaluated by indirect tensile stiffness moduli, split intensities before and after freezing and thawing, failure strains and adhesive toughness indexes at different load frequencies. The result shows that （ 1 ） stiffness modulus under low frequency condition, adhesive toughness index and freeze-thaw split intensity ratio can be used as the parameters to evaluate the mechanical property of asphalt mixture contains RAP; （2） there is a correlation between asphalt content of RAP and the mechanical property of asphalt mixture contains RAP, with the increase of old asphalt content, indirect tensile modulus increases, adhesive toughness index decreases, freeze-thaw split intensity ratio decreases and worsen mechanical property.