Modulus Study And Engineering Application Of Asphalt Mixture Based On Low Temperature Test And Micromechanical Method

Asphalt mixes are widely used in highways because of their good road performance and serviceability as well as their easy maintenance.Asphalt mixture is a complex and complex material composed of asphalt,mineral powder,aggregate and other materials.Under different mechanical conditions and temperature,asphalt mixture presents complex mechanical properties such as elasticity,viscoelasticity and elasto-plasticity.Its mechanical mechanism is very complicated.Especially the low temperature performance of asphalt mixes,most of the research methods so far still use the combination of experience and macroscopic research.Especially at-20℃and-35℃this lower temperature,work at home and abroad(especially the test)is relatively limited,a considerable part of the work is the use of 5℃indicators indirectly reflect and predict the low temperature performance of asphalt mixture.This work is based on the idea of low temperature compression test put forward by Professor Zhu Han and combined with new experimental and theoretical methods,a method of directly analyzing and calculating the mechanical properties of asphalt mixture at low temperature is proposed.As the asphalt mixture can be regarded as the composite material composed of asphalt mortar and coarse aggregate.Based on the theory of micromechanics,the two-step method is used to estimate the low temperature elastic modulus of asphalt mixture.The first step is to use the test method to measure the mechanical properties and parameters of the asphalt mortar.The second step is to calculate the low temperature elastic modulus of the asphalt mixture according to the mechanical model of the composite material,such as the low temperature elastic modulus,the coarse aggregate and the volume ratio of the asphalt mortar.Finally,according to the calculation results of low temperature elastic modulus of asphalt mixture,it is proposed to improve the middle layer of asphalt in Linxian to Baijiao section of Inner Mongolia high speed Inner Mongolia,and obtain the better engineering and economic benefit.The main innovations in this paper are as follows:1.In this paper,the low temperature compression test of asphalt mortar is putforward,and the compression curves of two kinds of asphalt mortar at different temperature and different rate are measured.The curve is analyzed and the low temperature elastic modulus of asphalt mortar is calculated.Then the elastic modulus is analyzed,and the minimum number of specimens for each group of parallel tests is proposed according to the correlation method of mathematical statistics.2.In this paper,the equivalent modulus of two-phase composite materials is calculated.The maximum modulus of asphalt mortar composites is calculated based on the elastic modulus of asphalt and fine aggregate and the volume fraction of asphalt mortar.And the relationship between the elastic modulus of the components of the asphalt mortar and the low temperature elastic modulus of the asphalt mortar was analyzed.3.In this paper,the generalized self-consistent model is used to predict the elastic modulus of AC-20 asphalt mixture at-20℃ and-35℃,respectively.In this paper,the low temperature elastic modulus of AC-20 asphalt mixture at-35℃ is predicted for the first time.And the effect of each component on the low temperature elastic modulus of asphalt mixture was clarified.4.Based on the results that the low temperature modulus of SBS modified asphalt mixture obtained in this work is higher than that of matrix asphalt mixture,the optimization design of surface pavement in Linhe-Baijuehe section of Xinjing Expressway in Inner Mongolia is presented.The original design of the asphalt surface by the modified asphalt modified asphalt,and achieved good engineering and economic benefits.