Research On Performance And Frost Resistance Of Diatomite-Crumb Rubber Composite Modified Asphalt Mixture In Seasonal Frozen Area

Because of the large temperature difference between day and night in winter in seasonal frozen area, the freezing and thawing damage of asphalt pavement is particularly serious and the destruction of freezing and thawing cycles to the crumb rubber asphalt pavement is an important problem in the road design project. Therefore, it has important practical significance to carry out the research on the frost resistance of crumb rubber asphalt pavement in seasonal frozen area.Based on the major scientific and technological projects of Jilin Province "Research and Product Development on Green Ecological Bridge Deck Pavement Material in Seasonal Frozen Region", the research mainly aimed at the frost resistance of crumb rubber modified asphalt pavement which has the function of removing snow and ice breaking. In order to ensure the performance and frost resistance durability of crumb rubber asphalt pavement in seasonal frost area, the diatomite was used to modify the crumb rubber asphalt pavement and the diatomite and crumb rubber composite modified asphalt mixture was put forward in this paper. Taking crumb rubber modified asphalt mixture, diatomite and crumb rubber composite modified asphalt mixture and SBS-crumb rubber modified asphalt mixture for research objects, the main research contents are as follows:(1) The gradation composition and the adding method of diatomite were determined by material features and design goals. The optimum proportion of three kinds of crumb rubber modified asphalt mixture was determined by the Marshall stability tests in this paper.(2) The road performance of three kinds of crumb rubber modified asphalt mixture was studied through the high temperature rutting test, small beam bending test at low temperature and freeze-thaw splitting test. The influence of the size and content of crumb rubber and the content of diatomite and gradation difference on crumb rubber asphalt mixture was also tested.(3) Frost resistance of three kinds of crumb rubber asphalt mixture was tested by freeze-thaw split test and dynamic indirect tensile stiffness modulus test. This paper carried out the study on the changing trend of the void rate, splitting tensile strength, splitting strength loss, coefficient of frost resistance, damage variables, dynamic indirect tensile stiffness modulus, peak load and horizontal stress of the three kinds of crumb rubber asphalt mixture under the influence of freeze-thaw cycles.(4) Compared with the common freeze-thaw damage prediction model of asphalt mixture, this used the non-equal interval MGM(1, m) to establish freeze-thaw damage prediction model of three kinds of crumb rubber asphalt mixture on the basis of void ratio and freeze-thaw damage variable.Research conclusion: the main influencing factors of the void ratio and water stability of crumb rubber asphalt mixture were determined. Diatomite can improve the pavement performance of crumb rubber asphalt mixture, and it can also improve the frost resistance of crumb rubber asphalt mixture. The freeze-thaw damage prediction model of crumb rubber asphalt mixture(non-equal interval MGM(1, m)) has a good prediction accuracy which could provide some reference for predicting the change trend of freeze-thaw damage for a long period.