Experimental Study On High Temperature And Fatigue Properties Of Basalt Fiber Asphalt Mixture

High temperature rutting and fatigue cracking are typical diseases of asphalt pavement,which seriously affect the service level of highway.The addition of fiber can effectively improve the performance of asphalt mixture,especially the basalt fiber is widely concerned because of its excellent mechanical properties and good compatibility with asphalt mixture.However,the effect of basalt fiber on improving high temperature performance,fatigue performance and evaluation index of asphalt mixtures with different gradations have not been systematically studied.Therefore,different high temperature performance test methods and fatigue tests under different control modes were used to study the performance of basalt fiber asphalt mixture.Firstly,the Marshall test and Rotary compaction test were used for the mixture design of SMA-13,Superpave-20 and Superpave-25 to determine the mineral gradation and the optimal asphalt ratio.The specification and content of basalt fiber were determined according to the preliminary test.Secondly,rutting test,uniaxial penetration test,dynamic modulus test and dynamic creep test were used to study the influence of basalt fiber on the high temperature performance of asphalt mixture.The test results show that the basalt fiber can greatly improve the high temperature performance of the asphalt mixture.The mathematical relationship between the test indexes obtained by different test methods shows that there is a good correlation between the different test indexes,which can be used as a basis for people to understand the improvement of performance of basalt fibers on asphalt mixture.Then,four-point bending fatigue tests with stress and strain control modes were carried out to study the effect of basalt fibers on the fatigue properties of asphalt mixtures.Based on the analysis of phenomenological theory,it is shown that the test results of basalt fiber on the increase of fatigue times of asphalt mixture are consistent under the two control modes of stress and strain,and the fatigue life of asphalt mixture has a good linear relationship with the stress and strain level in the semi-logarithnic coordinates.Based on the analysis of energy dissipation theory,it is shown that the cumulative dissipation energy of asphalt mixture under the two control modes of stress and strain has a linear relationship with the f-atigue life in logarithmic coordinates,but the fitting coefficients of the two control modes are not uniform.Finally,the energy dissipation ratio was used to analyze the decay characteristics of basalt fiber asphalt mixture fatigue performance.’IThe results show that the stability of energy dissipation ratio of basalt fiber asphalt mixture is consistent under stress and strain control,but this phenomenon is inconsistent with the engineering practice results,which indicates that the fatigue performance of basalt asphalt mixture evaluated by this method needs to be discussed.In addition,in the strain control mode,since the stiffness modulus of the basalt fiber asphalt mixture reaches 50%of the initial value,the failure stage has not yet been reached,and the fatigue life of basalt fiber asphalt mixture should be determined by the number of loading cycles corresponding to the 50%reduction of the stiffness modulus of basalt fiber asphalt mixture.