Research On Anti-Cracking Performance Of Grouted Semi-Flexible Mixture And Optimization Of Pavement Structure Layer

The poured semi flexible mixture has good anti rutting performance and water stability,but its anti cracking performance is still lacking.In order to further improve the comprehensive performance of semi flexible pavement,based on existing research,this paper analyzes the crack resistance mechanism and influencing factors of poured semi flexible pavement,designs a base asphalt mixture that meets the performance indicators of the semi flexible mixture through mix proportion design of the base asphalt mixture,and tests the performance of cement grouting materials mixed with different types of polymers,Propose a modified grouting material that can improve the crack resistance of the poured semi flexible mixture,and then use finite element simulation to simulate and calculate the application and crack resistance of the polymer modified poured semi flexible mixture in the pavement structure.Finally,analyze and summarize the construction process applicable to the polymer modified poured semi flexible pavement.In this thesis,SBS modified asphalt with good viscoelastic properties,as well as two different types of polymers,redispersible latex powder and epoxy resin,were selected to study the crack resistance of the poured semi flexible mixture.The main conclusions are as follows:(1)Analysis on the cracking mechanism and influencing factors of poured semi flexible materials.Through literature research,the cracking mechanism of poured semi flexible mixtures at the macro and micro levels was analyzed.The analysis shows that the cracks in the poured semi flexible pavement are mainly caused by the large mechanical performance gap between the grouting material and the base asphalt mixture,and the interfacial adhesion problem between cement and asphalt.By analyzing the impact of material composition,pavement structure,environmental factors,and volume stability on the crack resistance of the poured semi flexible pavement,it is concluded that the mix ratio of the mixture,the selection of layers in the pavement structure,and the volume stability of the cement grout itself will have an impact on the crack resistance of the semi flexible pavement,and it is proposed that polymer modifiers can improve the crack resistance of the semi flexible mixture.(2)The mixture ratio design of the base asphalt mixture is based on the design of GOAC-13-Ⅱ and GOAC-16-Ⅱ grading,and the Marshall stability and porosity of the mixture are tested.It is concluded that the stability and porosity of the mixture meet the requirements.Through leakage analysis test and flying test,the mixture ratio and the optimal asphalt aggregate ratio of the mixture are verified,and two types of base asphalt mixture suitable for semi flexible pavement are obtained.The asphalt aggregate ratio is 3.4% and 3.2%,the void ratio is 22.47% and 24.34%,and the grouting ratio is greater than 95% of the base asphalt mixture.(3)Composition design and performance study of polymer modified cement based grouting materials.It is preliminarily proposed that the water cement ratio of cement based grouting material is 0.63,and the sand cement ratio is 0.5.Through adjusting the water content in the mix proportion,the mortar fluidity is controlled to be 10 seconds to 14 seconds,ensuring the basic grouting performance of cement based grouting material.Then,compare the performance of two types of grouting materials with different amounts of redispersible latex powder and epoxy resin,and test the performance of the grouting material through compressive strength,flexural strength,and shrinkage tests.Finally,determine the mix ratio of polymer modified cement grouting material as follows:redispersible latex powder: water cement ratio 0.48,sand cement ratio 0.5,and polymer cement ratio 0.15,and epoxy resin: water cement ratio 0.405,sand cement ratio 0.5,and polymer cement ratio 0.15.(4)Study on the crack resistance performance of the poured semi flexible pavement,compare the performance indicators of two different gradations with different types of polymers added.Test the basic performance indicators of the mixture through immersion Marshall test,freeze-thaw splitting test,and dynamic stability test.On the basis of meeting the basic performance indicators,analyze the low temperature crack resistance and shear resistance of the mixture to analyze the crack resistance performance of the poured semi flexible mixture.The analysis shows that the epoxy resin modified poured semi flexible mixture is superior to the redispersible emulsion powder modified poured semi flexible mixture in both road performance and crack resistance.The residual stability increased by an average of 3%,the splitting strength ratio increased by 7%,the splitting tensile strength increased by 14%,the dynamic stability increased by 12.5%,the failure strain increased by 6%,and the shear resistance improved by 7.5%.(5)Research on the structural layer selection of the poured semi flexible pavement,analyze the structural mechanical response of the poured semi flexible pavement through finite element simulation,set up four different structural forms of pavement structure combinations,and analyze the stress situation of the poured semi flexible pavement in the pavement structure.By analyzing the tensile stress,strain,and surface deflection of each layer of four different pavement structures,it is concluded that when the poured semi flexible mixture is used as the upper layer structure of the pavement structure,the tensile stress at the bottom of the lower layer decreases by a maximum of 56% compared to other layers,and the surface deflection decreases by 18% compared to the ordinary asphalt mixture pavement.Therefore,it is recommended to apply the poured semi flexible mixture to the upper layer of the pavement structure,It can effectively improve the crack resistance performance of the pavement structure.(6)Research on the construction technology of grouted semi flexible pavement.Based on the characteristics of grouted semi flexible pavement,the construction suggestions for grouted semi flexible pavement in the production and transportation of base asphalt mixture,production and grouting technology of grouting material,surface treatment and curing after grouting,and quality control of construction engineering are summarized.