Study On Microstructure And Properties For Epoxy Asphalt

The paving problem of steel deck has been widely concerned all over the world.Epoxy asphalt binder is a good material for steel deck pavement because of its excellent high temperature stability,high strength and fatigue resistance.However,the increasing of viscosity of most epoxy asphalt binders is too fast in the mixing process and the control of time is too strict,which affects the deck paving of epoxy asphalt.And the ductility of epoxy asphalt binder is poor after curing.Therefore,the development of epoxy asphalt has important practical value.The Infrared,viscosity change,macroscopic mechanical properties and miscrostructure of different epoxy asphalt binders including homemade epoxy binder(HA),Japanese epoxy asphalt binder(TAF)and Chinese epoxy asphalt binder(5210)were studied.And the curing process of epoxy asphalt binders was described by the relationship between curing time and epoxy group conversion,the chemical reaction of epoxy asphalt binders during curing process was characterized by the change of the functional groups;The mathematical model between the time,the temperature and the curing degree of the HA epoxy asphalt was built up.The viscosity change of epoxy asphalt binders during the curing process was analyzed,which has the practical value to the construction.Meanwhile,the tensile strength and elongation at break of the epoxy asphalt binder during the curing process were also researched;the creep at low temperature and temperature susceptibility of epoxy asphalt binders were also analyzed.The changes of the microstructure for epoxy asphalt binder during the curing process were comprehensively analyzed.The performance of the epoxy asphalt binder can be understood systematically by these researches.The main conclusions can be drawn as following: the curing reaction of HA and TAF epoxy bitumen is first order reaction,while the curing reaction of 5210 epoxy asphalt is four grade reaction;The reaction rate for HA and TAF epoxy bitumen at high temperature is slower,and the reaction rate of 5210 epoxy bitumen is faster;The viscosity growth of HA and TAF epoxy asphalt change slowly with curing time.The viscosity of 5210 epoxy asphalt increases rapidly with curing time.This indicates that it is favorable for the mixing and compaction of HA and TAF epoxy asphalt,while the viscosity of 5210 epoxy asphalt must be strictly controlled to avoid excessive increasing;The mathematical relationship between the viscosity,time and temperature of 5210 epoxy asphalt is simulated to control the mixing time relatively.The temperature sensitivity of HA epoxy asphalt in the mixing process is lower than the TAF epoxy asphalt,and HA epoxy asphalt has a relative advantage in practical engineering;The tensile strength of HA and TAF epoxy asphalt is superior to the tensile strength of 5210 epoxy bitumen;The curing of HA and TAF epoxy asphalt is mainly concentrated in the long curing period,while the tensile strength of 5210 epoxy bitumen is basically formed after the 4h short high temperature,and the long-term curing is slow;The stiffness modulus of thee epoxy asphalt binders increase and the creep rate decrease with the increase of curing time,which illustrated that the low temperature properties of epoxy asphalt binder is poor with the increase of curing time.The temperature sensitivity of HA epoxy asphalt is obviously less than 5210 and TAF epoxy asphalt,indicating that HA epoxy asphalt has good tolerance ability to low temperature;With the increase of the curing time,the bright points have gradually appeared after 2h in aspahlt.This shows that the state of mutual inclusion between the asphalt and the epoxy resin appeared;The flowing state of asphalt appears between the aggregate and the aggregate at initial curing time.The adhesion between the aggregate and the aggregate becomes smaller with the increase of the curing time and the disappearance of flowing state.However,a small amount of adhesion between aggregate and aggregate still exists in 5210 epoxy asphalt after long-term curing.