Study On Super High Temperature Performance Of Composite Base Asphalt Pavement In Heavy-duty Traffic

Rutting is one of the primary damage in the asphalt mixture pavement, the phenomenon of rutting damage on the asphalt pavement is even more serious,specially under heavy load traffic conditions and high temperature area. As such, supported by the traffic science and technology projects of Shandong province-"Research of the composite base asphalt pavement superp performance and modification mechanism in heavy-duty traffic", the super high temperature performance of the composite base asphalt pavement which consists of flexible base-Large Stone Porous asphalt Mixes and semi-rigid base, which is widely used in Shandong province was studied; The Buton rock asphalt and anti-rutting agent were used respectively in the courses of middle and lower asphalt mixes to modify in high temperature.By means of superposition of the high-temperature modification to improve the rutting resistance of composite base asphalt pavement, so that the asphalt pavement can reach the super high temperature performance in heavy-duty traffic.Based on the reviews of literature and project research at home and abroad, the laboratory test, theoretical analysis, and numerical simulation were conducted to achieve the objectives of the paper.The objectives of the paper mainly include three contents:(1)The pavement performance and mechanical properties of the modified asphalt mixture, which was modified by the materials(Buton rock asphalt, PR anti-rutting agent);(2)The rutting prediction of the composite base asphalt pavement in heavy-duty traffic based on the method of viscoelastic theory and nonlinear finite element;(3)Contrastion and analysis the mechanical properties of composite base asphalt pavement structure in heavy-duty traffic in the high temperature condition and design condition.The conclusions of the study were drawn:(1)Based on the high temperature property, water stability, the low temperature performance and engineering economics of compound modified by SBS and PR AC-20, the rational dosage of PR anti-rutting agent was determined2.7%o.(2)The high temperature property of BRA modified asphalt mixture Superpave-25was obviously improved, water stability increased slightly, the low temperature performance slightly decreased; Comparing compound modified by SBS and PR AC-20with SBS modified asphalt mixture AC-20,the high temperature property was significantly improved, water stability and the low temperature performance was declined, but all met standard requirements.(3)The paper established the dynamic modulus master curves of BRA modified asphalt mixture Superpave-25, base asphalt Superpave-25, and compound modified by SBS and PR AC-20, SBS modified asphalt mixture AC-20and so on seven kinds of asphalt mixtures.(4)Rutting depth of the asphalt pavement, whose middle and lower asphalt mixes layers were modified was less than that of the unmodified asphalt pavement in each axle-load acting numbers and load level.(5)The paper found that the variation of the permanent deformation in different axle-load numbers(different traffic volume) was similar to the rule reflected by the creep curves of asphalt mixture. Deformation deformation of asphalt pavement structure which were modified were less than that of unmodified asphalt pavement under various axle-load numbers, and the rate of deformation was gentle than that of unmodified asphalt pavement.(6)The paper established a prediction equation between rutting depth and axle-load numbers in modified asphalt pavement; Using this equation, we could deduce that when the rutting depth of two kinds of asphalt pavement reached to critical depth15mm; Comparing with the unmodified asphalt pavement the timing of the modified asphalt pavement delayed and was about0.7～0.9times of that of the unmodified pavement.(7)The value of each calculation index(Horizontal tensile strain of asphalt layer, Horizontal tensile stress of the base, Vertical compressive stress of the stratified asphalt layer, Shear stress of the stratified asphalt layer, Vertical compressive strain of subgrade) of the asphalt pavement structure, whose middle and lower asphalt layers were modified, compared to the unmodified asphalt pavement were decreased in the high temperature condition and design condition. The middle and lower asphalt layers after modification by the modified materials could improve the fatigue life of asphalt layer and base layer and reduce the possibility of the permanent deformation, of the asphalt layers and subgrade.