| The pavement of highway long tunnel mostly adopts cement concrete pavement structure for safety reasons,but its surface function decays rapidly under the action of axle load and environment,which affects the safety performance of tunnels.The micro-surfacing thin layer can be used for maintenance,and effectively improve the surface function of tunnel cement pavement.However,the performance of ordinary micro-surfacing mixture is insufficient to withstand complex factors,and the bonding force with the old pavement is low.In view of this,water-borne epoxy resin with excellent performance is used to modify and optimize the micro-surfacing binder,and the strength,interlayer bonding force and anti-skid performance of epoxy emulsified asphalt thin overlay are analyzed in order to provide technical support for the restoration and maintenance of tunnel pavement surface function and pavement performance.Firstly,the technical specifications,curing conditions and curing mechanism of water-borne epoxy resin were analyzed.When the curing agent content was 10% and the curing temperature was 25?,the film forming performance and drawing strength of epoxy were the best,and then the epoxy emulsified asphalt was prepared by the optimum process.For the adhesion between epoxy emulsified asphalt and aggregate,considering the special requirement of water resistance of tunnel materials,a modified boiling analysis method was designed based on the conventional boiling method.The microstructure of emulsified asphalt was observed by fluorescence microscope,and the gray image was obtained for quantitative analysis.It is found that the emulsified asphalt exhibite a uniform epoxy network cross-linking structure when the epoxy content is 20%.Secondly,the epoxy emulsified asphalt was used as a binder to make a thin layer mixture.Based on the good workability,the asphalt-aggregate ratio based on water stability was designed.The influence of temperature,humidity and wind speed for tunnel on the strength of the mixture was analyzed,and the road performance of the mixture was studied.The results show that the grey correlation degree of temperature,humidity and wind speed to the cohesion of the mixture is more than 0.6,and the significance satisfies humidity > temperature > wind speed.When the optimum epoxy content is 20%,the initial strength of the mixture meets the requirements of open traffic and the final strength meets the requirements of hot mix asphalt mixture,wear resistance,water resistance,rutting resistance and spalling resistance are obviously better than ordinary emulsified asphalt and SBR modified emulsified asphalt mixture.In this paper,the interlayer bonding effect was evaluated by the pull test and the shear test,and the influence of the cover material,the interlayer viscous oil and the structural depth of the underlying layer on the interlaminar bond properties was analyzed.The results show that the bond strength is less affected by the composition of the cover material,but is highly correlated with the structural depth of the underlying layer and the amount of viscous oil.When the underlying layer is grooved cement concrete commonly used in tunnel,the interlayer tensile strength and shear strength of epoxy thin-layer overlay reach 0.37 MPa and 1.0 MPa respectively.Finally,based on the analysis of the factors affecting the anti-skid performance of pavement,the decay law of the anti-skid friction coefficient BPN of the thin overlay with different aggregate,aggregate gradation and cementing type under wheel load was studied by using indoor accelerated wear tester.The results show that the anti-skid ability of epoxy thin overlay can be improved when the mixture adopts diorite with good wear resistance,epoxy emulsified asphalt binder with high bonding strength and MS-3 median.The BPN tends to be stable and reach 60 when wearing 50,000 times.Compared with the curing standard,the epoxy thin layer has a higher anti-skid level. |
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