Study On Performance Of Polyurethane/epoxy Resin Modified Asphalt For Steel-UHPC Composite Bridge Deck Pavement

Steel-ultra-high performance concrete(UHPC)composite bridge decks have greater rigidity and smaller stress amplitude than steel decks,which effectively solves the problems of fatigue cracking and early diseases of flexible pavement on steel decks.However,the paving layer is still easily damaged.Epoxy asphalt has excellent properties such as high strength,good temperature stability,and strong adhesion.The service life of epoxy asphalt is much longer than that of ordinary asphalt.The use of epoxy asphalt in the paving layer and bonding layer of the steel-UHPC composite bridge deck structure will further exert the advantages of the composite bridge deck structure,and improve economic and social benefits.However,epoxy asphalt is prone to damage at low temperatures or repeated loads due to its thermosetting properties,which puts the pavement facing the risk of early failure.To reduce the possibility of early failure of the paving layer,it is necessary to modify the epoxy asphalt to improve its flexibility,storage stability and other properties.In this study,polyurethane/epoxy resin was used to modify the asphalt binder,asphalt mixture,and asphalt bonding material.The curing process,viscosity-curing time characteristic,mechanical properties,and rheological properties of polyurethane/epoxy resin modified asphalt binder were evaluated by laboratory tests.The high and low temperature performances,water stability and anti-skid performances of polyurethane/epoxy modified asphalt mixture were tested.At the same time,the modification mechanism,mechanical properties,high-temperature performance and service performances of polyurethane/epoxy resin modified asphalt bonding material were studied in detail.The main conclusions are as follows:(1)For polyurethane/epoxy modified asphalt binder,as the curing reaction progresses,the polyurethane/epoxy molecules are cross-linked,and finally form a continuous and stable network structure.The viscosity of binder increases slowly at first,and then increases rapidly after reaching the gel point.Polyurethane/epoxy resin greatly improves the tensile strength and high-temperature rutting resistance of asphalt.Polyurethane improves the flexibility and low temperature performance of epoxy asphalt.In addition,polyurethane/epoxy resin has good compatibility with asphalt.(2)The road performance test results of the modified asphalt mixture show that,compared with the styrene-butadiene-styrene copolymer(SBS)modified asphalt mixture,the high-temperature performance of the polyurethane/epoxy modified asphalt mixture is far better than the former,and the low-temperature performance and water stability are slightly worse.Considering the performances of polyurethane/epoxy resin modified asphalt binder and its mixture,35% is the best content of modifier.(3)For polyurethane/epoxy resin modified asphalt bonding material,the epoxy group in the polyurethane/epoxy resin reacts with the amino group in the curing agent to form an interpenetrating polymer network.The viscosity growth rate of polyurethane/epoxy resin modified asphalt is greatly affected by the temperature and the content of the modifier.Polyurethane greatly improves the flexibility and storage stability of epoxy asphalt.The mechanical properties and high temperature stability of polyurethane/epoxy resin modified asphalt are far better than those of SBS modified asphalt.And the service performance of polyurethane/epoxy resin modified asphalt can also meet the requirements of waterproof bonding layer of steel-UHPC composite bridge deck.