Research On Performance Of Joint Sealant For Cement Concrete Pavement Based On Viscoelastic

Joint sealant for cement concrete pavement is a kind of viscoelastic material,performance of which impacts on the service quality and life of pavement. At presentthe limitations of existing theory on sealant performance are exposed constantly: notconsidering the effect of multi-factor, singularity of research methods, simpleviscoelastic model and so on. Therefore, it is urgent to study performance of sealantbased on viscoelastic theory through finite element method.Based on experiment and analysis of Ansys, Performance of sealant was analyzedunder temperature load and vehicle load and coupling function, mechanicalcharacteristics of sealant were studied, and four failure modes were proposed.Through strain scanning and stress relaxation experiments of three common typesof sealant, sealant line viscoelastic scope and stress relaxation characteristics weredetermined. Then viscoelastic model was selected by test data curve fitting.viscoelastic parameters in different temperature were calibrated, and some regressiveformulas of the viscoelastic parameter of sealant were provided. The results show that11parameters of the generalized Maxwell model is used to simulate the viscoelasticperformances of HB-80asphalt and M950polyurethane sealant, the viscoelasticmodel of Y910silicone sealant is5parameters of the generalized Maxwell model.Based on elastic-viscoelastic theory, slab-sealant-slab model was established, andthe model of usability was demonstrated by EverFE software. Temperature distributionof cement concrete slab was determined by thermal analysis, and then performance ofHB-80asphalt sealant in different temperature and poisson ratio was studied andcompared with the other two kinds of sealant. The research results indicate that: sealantis tensioned, compressed and sheared, the maximum stress of site is angular point, andthe stress relaxation of central is faster than the corner; at the low temperatureconditions, M950polyurethane sealant can satisfy the thermal expansion andcontracting of slab, while at high temperature conditions, performance of Y910silicone sealant is best.Based on dynamic load model, considering load type, poisson ratio, aggregatelock and temperature factor and so on, the stress state of HB-80asphalt sealant wasanalyzed under dynamic loading and the sites of the largest stress were determined atdifferent loading time. Moreover, the characteristics for the three types of sealant under dynamic load were investigated in different temperature condition. Conclusions areobtained as follows: sealant is repeatedly sheared along the diagonal under repeatedvehicle load; the stress of sealant is closely related to the loading process. Whencompletely unloaded for a while, there is the residual stress in sealant.Based on the model of temperature and vehicle load coupled, verticaldisplacement of slab, change value of joint width and mechanical characteristics forthree kinds of sealant were discussed. Through comprehensive analysis, the failuremechanism of sealant was discussed, and four failure models of sealant were revealed.Research results indicate that: shear stress the middle of sealant is mainly determinedby the vertical displacement; joint width change is the main factor of tensile stress insealant; and the four failure models of sealant were debonding failure, cracking failure,spillage failure and foreign hard embedded failure.