| Under the long-term effects of loads and environmental factors,the texture depth of the cement pavement has been declining continuously.The friction coefficient has been continuously reduced,the antiskid performance has been gradually attenuated or lost,and then the traffic safety is threatened.In order to solve these current conditions,the preventive maintenance is urgently needed to restore the road surface function and prevent the further development of the disease.The restoration of road surface functions is of great significance for ensuring the safety of traffic.Epoxy anti-skid overlay is a new technology for preventive maintenance.Its excellent road performance has been confirmed by engineering practice.It has broad application prospects in the context of large-scale conservation.However,at present,the research and development of epoxy resin bonding materials,the establishment of durability evaluation index system and the design method of overlay have not been formed yet.The material and structural characteristics of epoxy anti-skid overlays for cement pavements are systematically conducted to solve these problems.This paving technology lays the foundation for the promotion and application in China.After the relevant specifications of epoxy anti-skid overlay and the application of solid engineering were investigated and analyzd,the technical performance indicators and requirements for epoxy bonding materials and aggregates were recommended.After optimization analysis of epoxy resin bonding materials,the tensile strength was evaluated.The composition of epoxy resin bonding materials is optimized by tensile performance test.The ratio of epoxy resin: curing agent: toughening agent: thinner: water is 100:20~30:20~30: 5~10:10~20.Epoxy resin adhesive was prepared according to the ratio and scanned by infrared spectroscopy and electron microscope.It showed that the performance of the glue was stable.Using the aggregate image measurement system and digital image processing technology,the shape features,angularity,and surface texture of the four aggregates were quantified.A comprehensive evaluation index of the aggregate shape features was proposed,and the indicators in the evaluation system were calculated using the AHP method.Combined with quantitative data,the aggregate evaluation index value of aggregates was calculated,and it recommend that the best overlay aggregate type is the basalt.The formation mechanism of bond strength between layers of epoxy anti-skid overlay was analyzed.The change of bond strength was divided into three stages: rapid growth,slow growth,and slow decline.The pull test and shear test was conducted in-house and on-site.The results have shown that the pull strength of the indoor epoxy overlay was 2.42 MPa,which was 6.03% lower than that of the on-site overlay.The cylindrical abrasion test specimen of the indoor epoxy overlay was used.The shear strength is 2.56 MPa,which is 3.52% lower than the shear strength of the cylindrical core sample on-site of the epoxy overlay.A finite element model of the tire-wear layer structure was established to analyze the effect of wheel weight,modulus and thickness of the wear layer,and horizontal force coefficient on the maximum shear stress between the wear layer and the road surface,and the maximum shear stress between the layers increased with the wheel weight.It grows linearly increases with the modulus of the overlya,decreases nonlinearly with the increase in the thickness of the overlay and increases with the increase of the horizontal force coefficient.Based on the principle of tribology,the composition of the friction between the tire and the epoxy overlay was analyzed.The finite element model of dry and wet tyres and overlays is established.The ground pressure and adhesion coefficient of the tire tread pattern,tire running status,tire running speed,wheel weight,tire pressure,water film thickness,wear layer thickness and other factors are analyzed.Regardless of whether it is a glossy tire or a patterned tire,the contact pressure is a symmetrical saddle-shaped distribution.The maximum ground contact pressure of the patterned tire is 13.27% greater than that of a smooth tire.Regardless of whether the wear layer surface is in a dry state or a wet state,the ground pressure decreases as the tire travel speed increases,the adhesion coefficient decreases as the tire travel speed increases,and the high-speed travel has a greater influence on the ground pressure and the adhesion coefficient.Tire contact pressure and adhesion coefficient increase with increasing axle load;tire ground pressure increases with tire pressure,adhesion coefficient decreases with increasing tire pressure.Both the pressure and the adhesion coefficient continuously decrease;the ground pressure and the adhesion coefficient of the tire both increase with the thickness of the wear layer.A prediction model for ground pressure and adhesion coefficient of tires was established.Combined with the test results of indoor friction coefficient,the prediction model was verified.It shows that the accuracy of model fitting is high.Accelerated wear tests were conducted,the anti-skid and anti-stripping decay laws of different basalt dosages,epoxy binder materials,basalt particle size,tire pressure,and test plate type with increasing number of interactions were analyzed.A corresponding decay model was established.The overlay life was estimated.Combining the UV aging test and the antifreeze performance test,the tensile strength of the epoxy overlay was evaluated.The results showed that the epoxy overlay has good anti-skid durability,anti-stripping durability,anti-ultraviolet aging properties and freeze-thaw performance.Based on the service characteristics of epoxy anti-slip wear layer,the epoxy anti-skid overlay durability evaluation system was proposed with the anti-skid durability,anti-stripping durability,UV aging adhesion,and frost-resistance.The method of system theory was introduced to clarify the composition,structure level and working environment of the epoxy anti-skid wear layer system.The design of the overlay was divided into three levels: epoxy adhesive material design,anti-skid aggregate design and epoxy overlay design.For each level of design content and control indicators,a system-based design process for epoxy anti-skid overlays on the cement pavement is proposed.Based on the investigation of the construction technology of the epoxy overlay,a standard epoxy overlay construction process for cement pavement was proposed,and an epoxy anti-sliding wear layer test project was built on the cement pavement of the Tianlin tunnel in Guangxi Longbai Expressway.After 23 months of operation,some slippage and grain detachment were observed.The anti-skid performance was tested.The texture depth was 1.25 mm and the friction coefficient was 0.75,which was higher than the road performance control index requirements.The on-site implementation effect was good. |
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