The Experiment Method Research On Shear Performance Of Aspalt Mixture

Currently, there are three main test methods to evaluate the high-temperature performance of bituminous mixture:tri-axial compaction test,single -axial creep test,rutting test.But they have certain limitations in evaluating the high-temperature performance of the asphalt mixture.This paper analyzes the reasons why permanent distortion forms mainly by using the shear test apparatus developed by SHRP,and points out that the shear stress of the mixture is mainly caused by the readjusting and shear flowing of the aggregate when subjected to traffic load.According to the RSCH research on 9 kinds of bituminous mixtures , it demonstrated that the RSCH can comparatively well evaluate the influence of graduation,asphalt binder,shear stress,oil/aggregate ratio and temperature on mixture's shear performance. The related experiment indexes can be used to evaluate the shear performances respectively at the beginning, during the middle and at the end of the repeated shear test,well reflecting the whole permanent distorting process of the asphalt mixture in high temperature . At the same time,it is pointed out that there is a direct relation between high-temperature failure and magnitude of the shear stress of the asphalt mixture.Through the FSCH test , the values of G* and G*/sinαunder different frequencies were obtained which were used to comparatively well evaluate the shear performance of the asphalt mixture,but the stage angle obtained couldn't reflect that. The shear performance of asphalt mixture increases with the increase of that of asphalt binder which has a power- function relationship with the plural modulus of the asphalt mixture.By the orthogonal tests,the order of the various factors was obtained according to the degree to which they could affect the shear distortion of the asphalt mixture. The order is as follows:shear stress- experimental temperature- gradation type - interval- asphalt type- asphalt content.