Multi-scale Research On Pavement Performance Of Glass Fiber Asphalt Mixture

With the rapid development of expressway construction in China,its traffic volume and traffic load have increased rapidly,making the early damage phenomenon of asphalt pavement increasingly prominent,leading to many practical problems such as frequent traffic safety hazards,reduced pavement life,and a sharp increase in later maintenance costs.The addition of fiber has become one of the important ways to comprehensively improve the performance of asphalt mixture,and the addition of fiber has played a significant role in improving the overall mechanical properties of asphalt mixture.Most scholars at home and abroad have studied the road performance analysis and research of asphalt mixtures on the basis of the macro-mechanical properties of asphalt mixtures,but there are few studies on the fiber micro-distribution and fiber mortar finite element of its fiber asphalt mixture.Therefore,based on the current research status at home and abroad,this thesis mainly focuses on the pavement performance of glass fiber asphalt mixture in two years of graduate studies as follows:(1)Through pavement performance tests such as rutting test,low-temperature trabecular flexural test,freeze-thaw splitting test,water-immersion Marshall test,etc.,the improvement effect of glass fiber on the pavement performance of asphalt mixture is analyzed.The test results show that when the content of glass fiber is 0.1% and 0.2%,the high temperature performance of the asphalt mixture is significantly improved.After exceeding 0.2%,the dynamic stability and permanent deformation of the asphalt mixture are no longer improved.For the low-temperature performance of the asphalt mixture,the flexural tensile strength of the mixture is not significantly improved,but the flexural tensile strain of the mixture is improved.For the water stability of the asphalt mixture,according to the results of the laboratory test and when the glass fiber content in the asphalt mixture reaches 0.2%,the strength ratio of the glass fiber asphalt mixture reaches the best.the optimal content of glass fiber with AC-13 grade asphalt mixture is 0.2%.(2)Through the MATLAB program and Auto CAD macro command,the random spatial distribution of glass fiber in asphalt mixture is realized,and the specimen model of different distribution of glass fiber in asphalt mixture is established through ABAQUS finite element software.Therefore,the internal stress distribution of fiber in specimens in trabecular flexural is studied.The results show that the horizontal distribution of fiber in asphalt mixture can better share the internal stress of asphalt mixture,and the reinforcement effect is more significant.(3)Through infrared spectroscopy analysis and electron microscopy of flexural tensile fracture,it was found that asphalt and glass fiber exist in the form of physical bonding.The tensile failure forms of glass fiber asphalt mortar can be divided into two forms: the failure of adhesion between fiber and asphalt mortar and the failure of cohesion of asphalt mortar itself.Based on two kinds of failure forms of glass fiber mortar,the tensile characteristics of glass fiber asphalt are numerically simulated,and the rule of the change of each parameter index on the single fiber tensile characteristics of glass fiber asphalt is analyzed,which reflects its change regularity.The results show that the pullout performance of glass fiber asphalt mortar can be improved by improving the strength and fracture energy of interface layer,the strength,fracture energy and cohesion of asphalt mortar and the embedding depth of glass fiber in asphalt.In summary,in this thesis,the pavement performance and parameters of glass fiber asphalt mixture are studied by test and numerical simulation,and some useful conclusions are obtained,which can provide theoretical basis and reference value for the engineering application of glass fiber asphalt mixture,and can also provide reference for the effective way of glass fiber to improve the performance of asphalt mortar.