Study On Short-term Thermal Aging And Rheological Properties Of Warm-mix Rubber Asphalt Binder

At present,a series of preliminary experiments have been carried out in the field of warm-mix rubber asphalt at home and abroad,but the relevant theories,tests and application technologies are not perfect,and there are many kinds of warm-mix agents and their action mechanisms vary greatly.Therefore,In this paper,two modified warm mixing agents,evotherm-M1 and hsbit,are used as modifiers to modify rubber asphalt with rubber powder content of 10%,15%,20%and 25%,respectively,so warm-mix rubber asphalt is obtained.In order to investigate the influence of two kinds of modified warm-mix agents on the short-term thermal aging performance of rubber asphalt.In this paper,three macro conventional indicators,elastic recovery,mass loss,dynamic shear rheological characteristics,brookfield rotational viscosity and micro infrared spectroscopy,thermogravimetric analysis were used.and the road characteristics of rubber asphalt and warm-mixing rubber asphalt studied deeply by analyzing the corresponding test indexes.The results show that the two kinds of warm mixing agents can reduce the penetration and increase the softening point of rubber asphalt,in addition,improve the high temperature stability,temperature sensitivity and recovery deformation ability of rubber asphalt after heat aging too.The higher the temperature,the worse deformation resistance and the better fatigue cracking resistance of warm-mix rubber asphalt.the higher content of rubber powder,the better deformation resistance and the worse fatigue cracking resistance after thermal aging,the deformation resistance of warm-mix rubber asphalt pavement is enhanced,while the cracking resistance is weakened.Within a certain range,the viscosity of warm-mix rubber asphalt decreases with the increase of testing temperature,rotor type,torque and rotational speed,and increases with the increase of rubber powder content.Two kinds of warm mixing agents make the vulcanized cross-linking fracture and the increase of aromatic primary amine of rubber asphalt to reduce the viscosity of rubber asphalt binder through chemical reaction,and the viscosity reduction effect of hsbit warm mixing agent on rubber asphalt is better than evotherm-M1 warm mixing agent.Waste rubber powder absorbs a large amount of saturates from asphalt through physical swelling in warm mix asphalt which makes increase relatively of the aromatic content,the content of C-S decreases while the content of aromatic sulfoxide S=O and aromatic primary amine-NH₂increases through chemical reaction in warm mix asphalt,thus changing the properties of warm mix asphalt.the thermal stability of two kinds of warm-mix asphalt rubber increases gradually with the content of rubber powder.When the matrix asphalt,warm mixing agents and rubber powder are blended,which improves the thermal stability of the copolymer,warm mixing rubber asphalt,compared with that of each monomer.Two kinds of warm-mix rubber asphalt satisfy the first-order kinetics equation,and different heating rates have little influence on the pyrolysis activation energy E,in contrast,have greater influence on the pre-exponential factor A of the two kinds of warm-mix rubber asphalt.