Research On Road Performance And Design Method Of Asphalt Mixture Based On Shear Compaction

At present,road engineering researchers have carried out a lot of research on the mesoscopic index(void ratio)and compaction characteristics of asphalt mixture,and on this basis,the design method and performance test applicable to various situations.The research results play an important role in guiding the design and construction of expressways.However,the current indoor test molding control standard still follows the previous compaction standard,and the performance verification also tests the conventional mechanical indexes according to the original traditional method,which is obviously inconsistent with the current highway performance requirements.Therefore,in view of the present research on asphalt mixture are limited on macro-scale,the incompatibility between the indoor forming method and field rolling condition in Marshall design method,quality control index and performance requirements are not matched and so on and so forth.This is based on a large number of researches at home and abroad,introduce a shear compactor that can maximum extent simulate the compaction condition of pavement construction,the specimens are prepared based on the mechanism of shear compaction,and the mesoscopic characteristics of asphalt mixture are studied on the basis.The organic correlation between physical variables and performance parameters is realized from the two levels of mesoparameters and performance indicators.The purpose is to provide multiple perspectives control basis for optimum design of pavement mixture.Based on this,the main contents of this study are as follows:(1)Research on the spatial distribution of important mesoscopic parameters(voids)and the influencing factors of void ratio of asphalt mixture based on shear box compactor.The function and application of this new type of equipment were further understood through the development process,working principle and characteristics of the shear box compactor.The void space distribution of the mixture was studied on the macro and micro level through cutting specimens and CT scanning.On this basis,a set of methods for preparing uniform specimens by shear compactor was developed.Finally,the influence of asphalt type,asphalt content,shear compaction times and fine aggregate gradation on the void fraction of the specimen was studied by grey correlation analysis.(2)Study on shear compaction performance of asphalt mixture.By comparing the compaction parameters(CEI,TDI,K1,K2)of asphalt mixture at two stages of shear compaction under different oil-stone ratios,the energy reserve index(ERI)was proposed to characterize the resistance of road surface to rutting and other diseases.(3)Road performance test study of asphalt mixture.Carry out uniaxial penetration test to study high temperature stability,and establish corresponding model verification based on discrete element software PFC;A comprehensive evaluation method for water stability of asphalt mixture is proposed by combining three water stability test methods;Based on viscoelastic mechanics the dynamic modulus result and the main curve are analyzed and the dynamic characteristics of asphalt mixture are characterized.(4)Determine the optimal asphalt dosage based on road performance test.The energy reserve index which is consistent with the field compaction of the mixture is determined by the shear compaction curve;the relationship between the high temperature performance of the mixture and the oil-stone ratio can be demonstrated by the uniaxial penetration test;the relationship between the index change before and after water damage and the oil-stone ratio can be characterized by the thickness of the effective asphalt film;and the relationship between the dynamic modulus and the oil-stone ratio can be used to characterize the low,medium and high temperature of the mixture.The mixture design of asphalt mixture based on road performance can be realized through four relationships.