Study On Properties Of Warm Mixed SBS Modified Asphalt Based On Before And After Thermal Oxidation Aging

With the development of national economic construction,canalization traffic and multi-regional construction have put forward higher requirements for asphalt pavement materials.SBS modified asphalt has good road performance,but its mixing and paving temperature are high.The warm mixed asphalt technology can effectively solve such defects;however,there is no conclusion on the subsequent performance problems caused by mixing the warm agent into asphalt,and there is not much research on the aging characteristics of warm mixed modified asphalt;the durability of the pavement is closely related to the performance and aging resistance of the asphalt in the aging stage,in particular asphalt is used as a cementing material.In this article,the more mature foreign Evo warm agent and domestic USP warm agent in the market were selected.In order to analyse and compare the effects of the type and amount of warm agent on the basic properties,low temperature rheological properties,microscopic morphology of SBS modified asphalt,as well as the performance change rule and anti-aging performance of warm mixed asphalt in the aging stage,the three indicators test,bush viscosity test,bending creep stiffness test and atomic force microscope test are done,the test result can provides reliable data to support for the warm agent to be popularized in the north area.The results basic performance test showed that:USP warm agent is not good for high temperature indexes(softening point,T₈₀₀00 and viscosity)of SBS modified asphalt,but it can improve the low temperature performance(ductility,penetration and T_1.2),and the higher the dosage,the greater the impact on SBS modified asphalt;Evo warm agent can improve the high temperature indexes(softening point and T₈₀₀)of SBS modified asphalt.Both warm agents can affect the temperature sensitivity and viscous flow,activation energy and reduce high temperature viscosity of SBS modified asphalt.The macro indexes of warm mixed modified asphalt gradually deteriorated with the increase of aging time and aging degree.The BBR test results showed that:USP can reduce the creep stiffness S of SBS modified asphalt,increase creep rate m,three kinds of creep compliance and viscoelastic ratio?,the higher the dosage,the better the effect of improving the rheological properties at low temperature;Evo warm agent can improve the stress relaxation ability of the SBS modified asphalt when the temperature is not lower than-24?basically,but the influence of the blending amount on the creep compliance of the modified asphalt was not strong.The compliance and?of the three kinds of asphalts decrease with the increase of the aging time and aging degree,which result in a decline in the low temperature performance,which was confirmed by the low temperature grade temperature T_LC.The results AFM test showed that:only SBS modified asphalt and Evo warm mixed asphalt had“bee-like structure”on the topography before and after aging,and the more serious the aging,the larger the size of the bee-like structure,but the smaller the number of bee-like structures.The quantitative analysis of micro indicators found that the higher the degree of aging,the smaller the roughness of SBS modified asphalt and Evo warm mixed asphalt,the larger the bee density,and USP warm mixed asphalt appeared different rules;it found that the correlation between micro-indicators and creep rate is the best,and it is more reliable to establish macro and micro connections by using exponential function model by correlation analyse.It found that the applicability of the dynamic aging equation by fitting the dynamic aging equations to the data of penetration,ductility,softening point,bush viscosity and creep stiffness.Based on the dynamic aging decision grey relational decision analysis,the aging resistance of the three asphalts is ranked from good to bad:Evo warm mixed asphalt>USP warm mixed asphalt>SBS modified asphalt,so it is recommended that Evo warm agent be used preferentially in cold northern regions.