Multi-index Control Method Of Parent Asphalt Mixture For Semi-flexible Pavement

Aiming at the problem that flexible pavement is easy to produce high temperature ruts and rigid pavement needs to set joints,researchers combined the advantages of both and proposed a semi-flexible pavement material design method.The parent asphalt mixture is an important part of the semi-flexible pavement,and the performance of the parent asphalt mixture is determined by several indexes and has significant influence on the durability of semi-flexible pavement.Therefore,it is of great practical significance to carry out research on the ratio optimization method of parent asphalt mixture to improve the comprehensive performance of parent asphalt mixture.In view of this,this thesis mainly carried out the following four aspects of research work.(1)The parent asphalt mixture with different asphalt types,gradations,oilstone ratio and fiber content was tested for leakage loss,porosity,coarse aggregate skeleton clearance ratio,permeability coefficient,Marshall stability and indirect tensile strength,and the range analysis method was used to optimize the mix ratio of the parent asphalt mixture.The results show that the high viscosity modified asphalt can effectively improve the performance of the parent asphalt mixture.The parent asphalt mixture has better performance when the passing rate of 2.36 mm is less than 9.5%,the oilstone ratio is 2.8%-3.3%,and the fiber content is 0.2%.(2)The preparation method of semi-flexible pavement materials was studied,and the proportion of semi-flexible pavement materials with excellent overall performance was selected by taking the perfusion rate and pavement performance as indexes;The influence of grouting fluid on the filling rate and pavement performance of semi-flexible pavement materials was investigated under different slope rates.The results show that the semi-flexible pavement material with high viscosity modified asphalt,3.3% oilstone ratio and 0.2% fiber content has good pavement performance.The greater the flow degree of grouting material,the greater the influence of slope rate on the perfusion rate and road performance of semi-flexible pavement.For semi-flexible pavement with slope rate,grouting material with flow degree of 14 s should be used.Finally,the construction technology of semi-flexible pavement is optimized.(3)The meso-structure of semi-flexible pavement materials was obtained based on digital image technology,and the cracking mechanism of semi-flexible pavement materials was analyzed by using meso-finite element method.The results show that the bonding interface in the tension zone of semi-flexible pavement materials fails first,and the lack of bonding interface strength leads to the poor cracking resistance of semiflexible pavement materials.Therefore,when designing semi-flexible pavement materials,the adhesive with high interface bonding performance should be selected.(4)The verification results of the test section show that the optimization method in this thesis has good feasibility and the paved test section has excellent road performance,which provides a good reference for the research and development of semi-flexible pavement materials and construction technology in the future.