The Research Of Low Temperature Cracking Mechanism Of Semi-Rigid Base Asphalt Pavement

With the advantages of driving comfort, fast traffic, convenient maintenance, strong bearing capacity and better stress dispersion, which can be better applied to the transportation of heavy traffic and overloading, semi-rigid base asphalt pavement becomes the main structure of highway and urban road in China. With the character of thermal sensitive, the mechanical property of asphalt mixture will change along with the variation of temperature. Because of being restrained by semi-rigid base which is with the high stiffness, thermal stress will be produced in asphalt concrete surface who cannot free shrink. When thermal stress exceeds the tensile strength of asphalt mixture, pavement surface cracking will happen namely, which will become transverse crack normally in the condition of comprehensive effect of driving and outside environment or circulating cooling. After produced thermal cracking, cracking propagation is related to the protection of asphalt concrete surface to semi-rigid base. So it is with important theoretical value and practical significance to carry out the relevant researches.Following researches on semi-rigid base asphalt pavement low temperature cracking mechanism are carried out in this paper.Firstly, according to the semi-rigid base asphalt pavement exposed to the outside environment long-term, performances of materials and structure will change with the variation of temperature. The influences of performance of asphalt, mixture composition, thermal coefficient of asphalt mixture, and semi-rigid base to semi-rigid base asphalt pavement were analyzed.Secondly, under the condition of different loading velocities and different temperatures, semi-circular bending tests were ran on asphalt mixture with the binder of 70# asphalt, SBS modified asphalt and rubber and plastic modified asphalt. The influences of binders, temperatures and loading velocities on stiffness, fracture toughness, fracture energy and tensile strength were studied.Thirdly, based on fictitious cracking model, the crack development of semi-rigid base asphalt pavement under the condition of one single cooling was studied. Crack opening displacement and sliding portion were solved in the case of only one fictitious crack, and interact with each other in the case of two fictitious cracks were studied.Fourthly, based on cohesive cracking model, the basic model of semi-rigid base asphalt pavement was built according to minimum crack space obtained in friction cracking mode. Under the condition of temperature cycling, internal temperature distribution, stress distribution, strain distribution and displacement distribution in pavement were analyzed by ABAQUS.