Research On The Influence Law And Improvement Technology Of Low-temperature Performance Of Semi-flexible Pavement Material

Infusion semi-flexible pavement is a rigid and flexible pavement material formed by filling large void asphalt mixture as the matrix and filling the internal voids with special cement-based grout.The material has excellent resistance to high temperature deformation,and has good application prospects in toll stations that are subject to heavy loads,climbing lanes and other road sections that are prone to rutting.However,the creep and relaxation capacity of infill semi-flexible pavement materials decreases correspondingly with the increase of modulus,which makes the material's ability to resist low-temperature shrinkage decline,and low-temperature shrinkage becomes a common failure mode for this type of pavement.The low temperature shrinkage of the semi-flexible pavement material and the further damage caused by it seriously affect the durability of the pavement.Therefore,how to reconcile the advantages and disadvantages of this material and improve its performance has become a problem that this material needs to be solved.In this study,the numerical simulation of the low-temperature cracking of the semi-flexible pavement and quantitative analysis of the influencing factors were carried out.According to the conclusion that reducing the modulus of the semi-flexible pavement material or enhancing its tensile performance and temperature shrinkage performance can significantly improve the low-temperature crack resistance of the semi-flexible pavement,it is proposed to add rubber polymer or emulsified asphalt to the grout To reduce the modulus of the mixture and improve the tensile properties of the mixture by using high viscosity and high elastic asphalt in the matrix.Secondly,in order to study the influence of mechanical properties on low-temperature performance,this study designed a multivariable test by changing the quality of asphalt(modifier)and grout performance(additive).The modulus characteristics,tensile properties and temperature shrinkage properties were studied.The test results show that the use of high-viscosity asphalt can significantly improve the tensile properties and temperature shrinkage properties of semi-flexible materials;styrene-acrylic emulsion can reduce the modulus of semi-flexible pavement materials.The appropriate amount of styrene-acrylic emulsion can improve the tensile performance and temperature shrinkage performance of the semi-flexible pavement material to a certain extent.In order to study the direct influence law of the mixture ratio against the low-temperature cracking performance,the effects of the matrix porosity,the type of grout,and the type of binder on the freeze-fracture temperature were studied based on the freeze-fracture test to evaluate the target porosity,asphalt viscosity and elasticity The effect of the benefit and the elasticity benefit of the grout on the low temperature crack resistance of the semi-flexible pavement material.The results show that the freeze-break test can effectively distinguish the low-temperature crack resistance improvement benefits of semi-flexible mixtures with different types of asphalt,different grouts,and different porosities.The freezing-failure temperature shows the law of decreasing first and then increasing with the increase of the matrix porosity.When the porosity is around 24%,the low-temperature performance of the infused semi-flexible material reaches the best;The improvement effect is obvious.Among them,the improvement effect of emulsified asphalt grouting material is better than that of rubber powder grouting material;the elasticity of the base asphalt is more beneficial to improve the low-temperature crack resistance of the semi-flexible material.Based on the research results of the influence law of low-temperature performance,a study on improving the low-temperature performance of the semi-flexible pavement material for infusion was carried out.Based on the use of high-viscosity asphalt and a porosity of 24%,the low-temperature performance of semi-flexible pavement materials is improved by grouting elasticity.This paper mainly studied the effect of styrene-acrylic emulsion and emulsified asphalt compound rubber powder on the improvement of low temperature performance and other properties of infusion semi-flexible materials.The test results show that styrene-acrylic emulsion and emulsified asphalt compound rubber powder can obviously improve the low-temperature performance of pouring semi-flexible pavement materials,and emulsified asphalt compound rubber powder has the best effect.The improved high-temperature performance and water stability performance did not change much,achieving the expected effect of improving performance.