Research On Bond Performances Between UHPC And SMA Of Ultra-high Performance Lightweight Composite Deck

The orthotropic steel bridge deck system has the advantages of small weight,large limit bearing capacity and wide application range.It is widely used in the construction of long span steel bridge.In order to solve the two difficult problems of fatigue cracking and early breakage of orthotropic steel bridge deck,the author of the study team proposed ultra high performance lightweight composite deck system.Paving the Ultra-High Performance Concrete(UHPC)on the steel bridge deck,and the surface layer is made of 35-50mm asphalt mixture.As UHPC and asphalt surface layer are thin layer structure,it is necessary to focus on the bonding problem between UHPC and the upper layer.This paper studies the bonding performance between the"UHPC-SMA"layers.The following work is completed,in view of the research status of the bond performance between steel and bridge deck pavement at home and abroad,understanding the main factors and existing problems that affect the mechanical performance of the interlayer,and studying the interlayer bond performance between UHPC-SMA of the 6 kinds of binders.The experimental studying on interlayer bonding performance of UHPC-SMA showed that the adhesive properties of epoxy adhesive layer oil,hot-melt modified epoxy resin and epoxy interfacial agent showed better performance than High viscosity and high elastic asphalt,rubber asphalt and epoxy asphalt.The high temperature bonding performance of epoxy asphalt is better than that of high viscosity and high elastic asphalt and rubber asphalt,but the three had no obvious differences at normal temperature.The ambient temperature has a great influence on the interlayer strength of UHPC-SMA.The shear strength of high viscosity and high elastic asphalt,rubber asphalt and epoxy asphalt respectively decreased by 70.2%,65.6%,55.74%,and the tensile strength respectively decreased by 89.4%,94.4%and 89.3%,and epoxy binder has obvious advantages at high temperature(60?).The shear strength of the epoxy adhesive layer oil,the hot-melt modified epoxy resin and the epoxy interfacial agent respectively reached 0.95MPa,0.72MPa and 1.14MPa,and the tensile strength respectively reached 0.18 MPa,0.21MPa and 0.19MPa.The hot-melt modified epoxy resin has excellent bonding properties at normal temperature and high temperature The experimental study on the dosage of epoxy resin and the life curing time showed that,when the epoxy resin content reached0.7kg/m~2,the interlayer bonding strength reached the requirement of bridge deck paving,and the adhesive strength continued to decrease,so 0.7kg/m~2 was chosed as the best dosage.The epoxy resin strength was affected by temperature and curing time.The curing time of epoxy resin at ambient temperature(20?)is more than 20 days.On the 20th day,the shear strength and tensile strength of epoxy resin have reached the requirements of bridge deck pavement.The results of finite element calculation showed that the strength of SMA is satisfied requirment and has sufficient safety reserve according to the design.Under the most unfavorable load combination,the peak shear stresses of the UHPC-SMA layer at 20?(normal temperature)and 60?(high temperature)are 0.696 MPa and0.422 MPa,and the peak tensile stresses peak between layers are 0.167MPa and0.152MPa.With the combination of the numerical simulation and the measured strength analysis,the epoxy adhesive layer oil,the hot-melt epoxy resin and the epoxy interface agent can meet the interlayer bond performance requirements both under the conditions of 20?(normal temperature)and 60?(high temperature)under the most unfavorable load combinations of overloading,emergency braking and dynamic load.high viscosity and high elastic asphalt,rubber asphalt and epoxy asphalt can not meet the requirements of interlaminar bonding at 60?(high temperature).