Study On Epoxy Asphalt Binder Self-healing Performance

With the increasing traffic load,the traditional pavement materials can’t meet the requirements of modern transportation.Epoxy asphalts are thought to be the next generation long-life paving materials,which were widely used in pavement of pavement and steel bridge deck because of its superior mechanical properties.However,epoxy asphalts are thermosetting or quasi-thermosetting materials,which may not have the self-healing capability of traditional asphalt materials.Therefore,it is easy to cause permanent damage once epoxy asphalts are destroyed.In order to overcome this problem,it is necessary to develop epoxy asphalt with good self-healing capability.While epoxy asphalt contains a lot of asphalt,there is also curing reaction of epoxy resin in the system itself.Therefore,we speculate that the self-healing capability of epoxy asphalt may come from two aspects:one is the self-healing capability of asphalt itself,the other is the self-healing capability provided by the curing reaction of epoxy asphalt.Firstly,in order to study whether the curing reaction in epoxy asphalt can continue during self-healing,the curing process of 2910 epoxy asphalt curing system was studied by differential scanning calorimeter(DSC)and dynamic shear rheometer(DSR).The results show that the curing reaction of epoxy asphalt was still going on after 10 hours when the curing temperature was 120~170~oC.It can be seen that the curing reaction of epoxy asphalt is far from complete curing after curing at 120~oC for 4 hours.Under certain conditions,the curing reaction will continue,which can provide certain self-healing capability for epoxy asphalt.In order to clarify the self-healing capability of epoxy asphalt and the factors affecting the self-healing capability,dynamic shear rheometer(DSR)and tensile tester were used to characterize the self-healing properties of epoxy asphalts with different maleic anhydride(MAH)ratios at different self-healing temperatures and self-healing time.The rheological test results shown that the complex modulus and glass transition temperature of self-healing samples with all acid anhydride ratios for 3 days at 60~oC were higher than those of self-healing samples for 3 days at 30~oC.For epoxy asphalt with a ratio of 100:2.0,the complex modulus and glass transition temperature of the specimens with stress loading were higher than those of the specimens without stress loading.These results imply indicated that probably stress-and thermal-induced chemical crosslink reaction occurred at the cut surface,and provide the self-healing capability of epoxy asphalt.Tensile test results shown that reducing the content of anhydride in epoxy asphalt,increasing temperature and prolonging time can increase the recovery ratio of the elongation at break and fracture strength at break of epoxy asphalt.In addition,for 100:1.8 and 100:2.0 samples,after 10 hours of self-healing at 60~oC,their tensile curves shown obvious stress enhancement These results further verified that,except for self-healing capability from filled asphalt,the self-healing capability of epoxy asphalt also originated from the continuation of curing reaction of epoxy asphalt.The results of rheological and tensile tests confirm our hypothesis that there are two sources of self-healing capability of epoxy asphalt:one is the self-healing capability of asphalt itself,the other is the self-healing capability provided by curing reaction of epoxy asphalt.High temperature and certain stress loading can promote the self-healing performance of epoxy asphalt.At the same time,paying attention to the proportion design in production and application,may provide a better self-healing basis for epoxy asphalt.