Study On Interlaminar Shear Behavior Between SMA Surface And UHPC Base Of Steel Bridge Deck Pavement

Orthotropic steel bridge deck system has the advantages of large bearing capacity,small dead weight and strong adaptability.It is widely used in the construction of long-span steel bridges to solve the early failure of surface pavement and orthotropic steel bridges.Due to the two major problems of panel fatigue and cracking,a treatment plan represented by the ultra-high performance lightweight composite bridge deck system appeared.The ultra-high performance concrete was laid on the steel bridge deck,and the surface layer was made of 35～50mm asphalt mixture.Because UHPC and asphalt pavement are both thin-layer structures,it is necessary to focus on the interfacial adhesion of composite pavement.This article is based on the steel bridge pavement project of Zhongshan west ring expressway in Guangdong province and is aimed at UHPC-SMA related researches have been carried out on the interlaminar shear properties.The gradation of SMA-13 was determined,and the best oil-stone ratio was determined by Marshall test to be 5.8%,and the rationality of the oil-stone ratio was verified by leakage test and flying test,and then water immersion Marshall test and freeze-thaw splitting were carried out.The crack test and high-temperature rutting test prove that the water stability and high-temperature stability of this grade are good.Four kinds of direct shear tests for interlayer waterproof adhesive layer were compared and screened.The order of shear strength at 20℃ was:Japanese TAF epoxy adhesive>8%SBS content modified high viscosity and high elastic asphalt>6%SBS content modified high viscosity and high elastic asphalt>finished SBS modified asphalt;the order of shear strength at 60℃ was:Japanese TAF epoxy adhesive>8%SBS content modified high viscosity and high elastic asphalt>finished SBS content modified asphalt>6%SBS content modified high viscosity and high elastic asphalt.Then,with the finished SBS modified asphalt as the bonding material,the five different surface treatment measures of UHPC were compared:no surface treatment,shot blasting 1,shot blasting 2,stone inlay 60%,stone inlay 80%.The order of shear strength is:stone inlay 80%>stone inlay 60%>shot blasting 2>shot blasting 1>no surface treatment.For shot blasting+finished SBS modified asphalt,shot blasting+ Japanese TAF epoxy adhesive,stone inlay+finished SBS modified asphalt,stone inlay+Japanese TAF epoxy adhesive,the four-layer interface structure combination,is subjected to five different degrees of aging:unaging,short-term aging,aging 2d,aging 5d,and aging 8d,and then a direct shear test with a positive pressure of 0.7MPa was carried out.The order of aging degree of shear strength is:stone inlay+Japanese TAF epoxy adhesive>stone inlay+finished SBS modified asphalt>shot blasting+ Japanese TAF epoxy adhesive>shot blasting+finished SBS modified asphalt.Then,direct shear tests were carried out under three different positive pressures of 0.3MPa,0.5MPa,and 0.7MPa on the combined stone+finished SBS modified asphalt.The results showed that the shear strength increased with the increase of the positive pressure,and the shear strength was obtained.Fitting equation with positive pressure.The shear fatigue tests of four kinds of interlaminar interface structure combinations under two aging degrees,two positive pressures and three different stress ratios were carried out,and the shear fatigue life equation was obtained.The order of fatigue life under the same interlaminar shear stress was as follows:stone inlay+Japanese TAF epoxy adhesive>stone inlay+finished SBS modified asphalt>shot blasting+Japanese TAF epoxy adhesive>shot blasting+finished SBS modified asphalt.