Research On Road Performance And Mechanical Properties Of Diatomite-basalt Fiber Compound Modified Asphalt Mixture

Because of the better driving comfort,higher stability and less noise,asphalt pavement has been widely used in road engineering.Engineering practice showed that asphalt pavement would appear a variety of diseases during its service period.There are many reasons for these diseases,but material properties of asphalt mixture are the main factors.The material properties of asphalt mixtures are extremely sensitive to environment,such as temperature,water and ultraviolet,etc.How to improve the above performances of asphalt mixture is the researchers’ most concern.The relevant research showed that the addition of modifications will reduce the temperature sensitivity and water damage.In this paper,based on the Project supported by Science Technology Development Program of Jilin Province "Study on the application of diatomite-basalt fiber compound modified asphalt concrete pavement repair in the seasonal frost area" and the Project supported by the National Natural Science Foundation of China "Research on the damage model and mesoscopic characteristics of asphalt concrete freeze-thaw cycle condition in seasonal frost area",the road performance and mechanical properties of diatomite-basalt fiber compound modified asphalt mixture were studied by means of laboratory experiments and theoretical analysis.The main work has been carried out as follows:1.The high and low temperature performances of diatomite-basalt fiber compound modified asphalt were evaluated.Firstly,the high and low temperature,viscoelastic properties of diatomite and basalt fiber compound modified asphalt were evaluated through cone penetration,softening point,viscosity,force ductility,dynamic shear rheology(DSR)and bending beam rheology(BBR)tests.Then,the effect of diatomite and basalt fiber on the performance of modified asphalt was discussed by using analysis of variance.2.The optimum content of diatomite-basalt fiber compound modified asphalt mixture was determined by response surface methodology.The CCD method in response surface method was used,the response values were made by void ratio,clearance rate,saturation,stability and flow value.Then the experimental design of three factors and three levels was design,diatomite content,basalt fiber content and bitumen-aggregate ratio were treated as the influence factors.Thus,response surface models were established according to the test response value.Next,the function equations could be fitted by multiple regression equations,and analysis of variance was performed.Finally,according to the specification requirements and engineering needs,the conditions for each response value were determined,the optimal content of diatomite and basalt fiber and the optimal bitumen-aggregate ratio were also determined.Meanwhile,the experimental test data were used to verify the model predictive values.3.In order to analyze the effect of diatomite-basalt fiber on asphalt mixture,diatomite modified asphalt mixture(DAM),basalt fiber modified asphalt mixture(BFAM)and asphalt mixture(AM)were selected for road performance study.Firstly,the optimum bitumen aggregate ratios of BFAM and DAM were determined.Then the high temperature stability,low temperature crack resistance,water stability and fatigue performance of four kinds of asphalt mixture were analyzed.Then,the creep deformations could be measured by uniaxial compression creep tests,and corresponding viscoelastic parameters were identified by Burgers viscoelastic model.Then the high temperature viscoelastic performances of matrix and modified asphalt mixture were analyzed.4.The fatigue resistance of diatomite-basalt fiber compound modified asphalt mixture was studied by four-point bending fatigue test.Firstly,the fatigue parameters of four kinds of asphalt mixtures were measured by Cooper multi-function pneumatic servo tester,and the fatigue performance of the modified asphalt mixture was compared.Then,the influences of optimal bitumen aggregate ratio,void ratio,voids in mineral aggregate,saturation,initial stiffness modulus,and cumulative dissipation energy on the fatigue life were analyzed using grey correlation analysis.5.Considering the effect of freeze-thaw cycles on damage of diatomite-basalt fiber compound modified asphalt mixture,four kinds of asphalt mixture were treated with different freeze-thaw cycles.The changes of indicators such as high temperature Marshall stability,low temperature splitting tensile strength and normal temperature splitting tensile strength were used to reflect the effects of freeze-thaw damage on high temperature stability,low temperature crack resistance and water stability of asphalt mixture.Then,the logistic model and multivariate Weibull model were used to analyze the damage characteristics of asphalt mixtures.By the comparison of the data and model analysis,the effects of diatomite and basalt fibers on the resistance to freeze-thaw damage of asphalt mixtures were evaluated.