| Epoxy asphalt is a thermosetting asphalt materials that composed of base asphalt and epoxy system that composed of epoxy resin and curing agent,as well as compatibilizer,diluent,viscosity reducer,polymer modified toughening agent and so on according to a certain proportion.And the epoxy asphalt is an irreversible,insoluble,high temperature thermosetting material after curing reaction between curing agent and epoxy resin in epoxy system.The thermoplastic property of matrix asphalt is changed.It is used as pavement material for long span bridge deck according to its excellent mechanical properties,high temperature stability,fatigue resistance and durability.However,the thermosetting epoxy asphalt materials used in bridge deck pavement have the insurmountable problems of fast curing speed,poor toughness,long curing time and so on.Epoxy bitumen materials are still difficult to be popularized in a large scale.The key to the problems of high temperature stability and poor toughness mainly depends on the performance of epoxy resin system.Therefore,it is great scientific significance and engineering application value to study epoxy system with suitable curing speed,good toughness,high strength and good economy.In this paper,the epoxy resin system for epoxy asphalt made up of self-made curing agent and Diglycidyl ether of bisphenol A(DGEBA)epoxy resin was studied.The relationship between curing control and properties of epoxy resin system was studied.The curing characteristics of epoxy resin system were measured by differential scanning calorimetry(DSC).The effects of curing agent content,curing temperature and curing time on the mechanical properties and glass transition temperature(T_g)of epoxy resin system used to modify asphalt were studied by means of universal mechanical property test machine and dynamic thermomechanical analyzer(DMA).The mechanical properties and the experimental data of DMA showed that the mechanical properties of epoxy resin system are improved with the increase of curing agent content.And the low temperature toughness of epoxy resin system is improved.The elongation at break and tensile strength of epoxy resin become worse and worse with the increase of curing temperature.At the same curing temperature,the tensile strength of the resin system increased gradually with the extension of curing time,but the elongation at break was opposite.The T_g of cured epoxy resin increases with the increase of curing time.This study provides a powerful basis for optimizing the curing process of epoxy asphalt.In this paper,Fourier transform infrared spectroscopy,Brookfield viscometer,universal mechanical property testing machine and simple beam pendulum hammer impact machine are used to investigate the effect of curing temperature on epoxy resin system for epoxy asphalt.Fourier transform infrared spectroscopy(FT-IR)was used to measure the change of epoxy conversion with curing time at different curing temperature s.The stability of curing agent at125?and 165?was studied.At this temperature,the curing agents begin to undergo oxidation decomposition reaction and lead to failure.The higher the temperature,the worse the stability of curing agent.The change law of the viscosity of epoxy resin system with time under different curing temperatures was analyzed by the Brookfield viscometer,which shows that epoxy resin system has the characteristic of slow curing at high temperature.The impact toughness and bending strength of epoxy resin curing system were analyzed by pendulum impact machine and universal mechanical testing machine.Therefore,in order to meet the construction requirements in practical engineering,the most suitable construction technology is 165?high temperature agitation storage of the short time and 60?solidification of the long time.Finally,the effects of high temperature curing time on the viscoelastic properties of epoxy system and the performance of epoxy asphalt were stud ied.The creep properties and life prediction of epoxy system under different stresses and temperatures were studied by dynamic thermomechanical analyzer(DMA).The results showed that the length of storage time at 165?has a direct effect on the creep recovery ability of epoxy system.The longer of the storage time at high temperature,the worse of the creep property of the materials.With the prolongation of high temperature storage time and the increase of tensile stress,the creep deformation and residual strain of the material increase sharply,which results loss of the life and creep property variation.Therefore,the storage time at 165?is strictly controlled to make the epoxy system have excellent viscoelastic properties in practical use.The compatibility,mechanical properties and glass transition temperature of epoxy asphalt at different high temperature curing time were tested by fluorescence microscope,universal mechanical property tester and dynamic thermomechanical analyzer.It is found that with the prolongation of high temperature curing time,the agglomeration of asphalt particles in epoxy asphalt increases,which leads to the deterioration of the overall compatibility.From the mechanical property and the data of DMA of epoxy asphalt,it can be seen that the tensile strength and elongation at break decrease slightly with the increase of curing time at high temperature.The T_g of epoxy asphalt changes little about-5?.However,from the data of modulus,it can be seen that the low temperature toughness and high temperature stability of the material become worse.Therefore,epoxy asphalt in construction and practical use should be avoided at high temperature for a long time of curing storage. |
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