Study On Performance Improvement Of Rubberized Warm Asphalt

Rubber modified asphalt technology has a huge advantage in the economic,environmental.However,the adverse effects on storage stability and construction workability of waste tire crumb rubber are always two obstacles to the development of rubber asphalt.With the aim to solve these two problems,in the paper,the rubberized warm asphalt with good workability was first prepared by warm mix technology.Afterwards,the modification of the warm mix rubber asphalt’s storage stability was carried out by Tans-polyethylene Rubber(TOR),Furfural Extract Oil(FCC)and Silane Coupling Agent(KH550),respectively.Besides,its technical performance was studied by a large number of laboratory tests.First of all,the test tube segregation test was carried out on the three types of modified rubber asphalt.Subsequently,the storage stability and the evaluation criteria of the material were studied by softening point,penetration degree,viscosity and dynamic shear rheological tests.The results show that it is accurate and reasonable to evaluate the storage stability of modified rubber asphalt by the viscosity and dynamic shear rheological test.The optimum concentration levels of the three types of modification measures are:5%TOR,FCC ratio of 6,and 1%KH550,respectively,and the 5%TOR is the best,which can reduce 52%of the relative viscosity and 50.9%of the segregation ratio.The low temperature comprehensive performance evaluation of three kinds of rubberized warm asphalt was carried out by low-temperature ductility,bending beam rheometer(BBR)and dynamic mechanical analyzer(DMA)tests.The influencing rules of the three kinds of modification measures on the complex modulus,phase angle,rutting factor and viscosity of warm mix rubber asphalt was studied by dynamic shear rheometer and Brookfield viscosity tests.The results show that the high-temperature stability of the rubberized warm asphalt after TOR modification has to certain extent improved,while there is no obvious change of the low temperature performance and viscosity.In regard to the material modified by FCC pretreatment crumb rubber,all indicators under low temperature has improved significantly with the decrease of Miscosity and improvement of construction workability,while there are some adverse effects on high temperature performance of the material.As for the material modified by KH550 pretreatment crumb rubber,the effects are mainly reflected in the improvement of high temperature performance,while the remaining indicators suffer no significant changes.The modification mechanism of three kinds of rubberized warm asphalt was studied by environmental scanning electron microscopy and infrared spectroscopy.The changes of the macroscopic properties of materials was explained from the perspective of meso-characteristics.The results show that all the three kinds of modification measures can improve the compatibility between the rubber and the asphalt.With FCC modification,their mixture is mainly physical swelling,while TOR and KH550 modification is mainly through chemical crosslinking reaction.Besides,the influencing rule of the three kinds of modification measures on the surface free energy of rubberized warm asphalt was studied by contact angle tests.This article provides the basis for the evaluation method and improvement measures of rubber asphalt temperature,and provides technical support for the popularization of rubber asphalt.