Study On The Influence Of Relative Molecular Mass Of SBS On The Performance Of Modified Asphalt And Its Mixture

SBS is widely used in the field of road materials because of its excellent improvement in the performance of asphalt.However,there are differences in structural parameters of different SBS,and the impact on asphalt performance may be different.Among them,the relative molecular mass is one of the most important parameters of SBS,which has a great influence on its physical and mechanical properties.Therefore,it is important to study the effect of SBS relative molecular mass on asphalt performance.In view of this,this paper studies the effects of different relative molecular masses of SBS on asphalt pavement performance,and provides a basis for the optimization of SBS relative molecular mass used in road asphalt modifiers.In this paper,based on five different relative molecular masses(79,000,87,000,106,000,124,000,138,000)of linear SBS,asphalt modification.The effects of SBS with different molecular weights on the high and low temperature properties of asphalt were studied by conventional index test method,force measurement ductility and DSR and BBR rheology tests.The compatibility of SBS modifier with asphalt was discussed.Furthermore,three different relative molecular masses of SBS were selected,and TFOT,PAV and UV aging tests were carried out on the self and its modified asphalt.The conventional indexes and rheological properties of the modified asphalts under different aging modes were analyzed.The difference of anti-aging properties of SBS modifier and its modified asphalt was revealed by infrared spectroscopy.The thermal stability of each modified asphalt before and after aging was analyzed by thermogravimetric test.Finally,through the mixture performance test,the effect of SBS relative molecular mass on the road performance of the mixture was evaluated.The results show that the higher molecular weight of SBS increases the high temperature performance of modified asphalt,while the low temperature performance increases first and then decreases.The modified asphalt prepared by SBS with relative molecular mass of 87,000 has the best low temperature performance.The SBS with a relative molecular mass of 73,000 has a poor modification effect.The viscosity of the modified asphalt increased greatly with the increase of the relative molecular mass of SBS.When the relative molecular mass was 138,000,the viscosity of the asphalt exceeded the upper limit of the specification and the compatibility with asphalt was poor.SBS with a relative molecular mass of 87,000,106,000,and 124,000 has a good modification effect on asphalt.Under different aging modes,the modified asphalt with high molecular weight of SBS has less change in basic index and rheological properties.The infrared spectrum of SBS modifier before and after aging showed that the relative molecular mass had no significant effect on the anti-aging performance of SBS itself,but the anti-aging property of modified asphalt was obviously enhanced when the relative molecular mass of SBS was higher.In addition,the modified asphalt prepared by SBS with a molecular weight of 124,000 has higher thermal stability after TFOT and PAV aging,but there is no significant difference between modified asphalt after UV aging.The results of the mixture performance test showed that the modified asphalt mixture had excellent low temperature crack resistance when the relative molecular mass of SBS was 87,000.The relative molecular mass of SBS is increased,which makes the asphalt mixture high-temperature anti-rutting ability and water stability enhanced.