| The infused semi-flexible pavement material(SFPM),which is obtained by infusing cement-based materials into a large-porosity asphalt mixture,is a kind of semi-flexible pavement material with the advantages of asphalt concrete flexible pavement and cement concrete rigid pavement and excellent rutting resistance,and has been mostly used in road intersections,airport pavements and toll stations and other road sections that need to carry heavy traffic in recent years.However,because SFPM is a composite structure material,it is easy to produce cracking disease,which leads to its restricted application and affects its promotion.At the same time,due to the sudden increase of passenger and freight traffic brought by the current economic rebound,the load-bearing capacity of the road has put forward higher requirements,therefore,how to further enhance the advantages of SFPM in carrying heavy traffic while solving its low-temperature performance deficiency has become an urgent problem to be solved.Silane coupling agents,cationic emulsified asphalt and styrene butadiene latex were studied as modifiers for infilled semi-flexible pavement materials.Firstly,the base asphalt mixture with large void ratio,high infill rate and high stability was optimized on the basis of the existing gradation by controlling the key particle size ratio of the gradation;secondly,the dynamic stability,bending and tensile strain and freeze-thaw splitting strength ratio of SFPM were used as evaluation indexes by using orthogonal experimental design,gray correlation analysis method and comprehensive weighted scoring method to analyze the effect of modifier types and their preparation process parameters on Then,based on the principal component analysis,the high and low temperature performance indexes of SFPM were analyzed to comprehensively evaluate the modification effect of each modifier on SFPM,and to determine the modifier with the best overall performance and the applicable conditions of each modifier.Finally,based on the composition and strength formation mechanism of SFPM,the mechanism of modification of SFPM high and low temperature performance by each modifier was investigated from the perspectives of material compounding effect and the strength of cementitious material by using tensile test,cementitious performance test,scanning electron microscope(SEM)and energy spectrum analysis(EDS).The research results show that: for semi-flexible asphalt concrete grade SFAC,the key particle size 2.36 mm aggregate content is controlled so that the matrix asphalt mixture connected porosity is not less than 23%,and the guaranteed filling rate is greater than 85%;the vibration frequency of silane coupling agent and cationic emulsified asphalt modified cementitious grouting materials are 50 HZ and 60 Hz,and the optimal dosing is 0.5% and 5%,respectively,and the vibration Compared with O-SFPM,the dynamic stability of C-SFPM has increased by 54%,and the score based on principal component analysis is also the highest for C-SFPM,which indicates that C-SFPM is suitable for higher temperature areas or pavements with higher requirements for heavy load and has the best overall performance;the maximum bending and tensile strain of S-SFPM has increased by 36%,which indicates that its lowtemperature crack resistance is good.The addition of silane coupling agent increases the interfacial modulus of SFPM by 242% and makes the composite state more stable,thus enhancing the overall composite degree of SFPM and improving the low-temperature crack resistance of SFPM;the chemical reaction between cationic emulsified asphalt and cement changes the microstructure of cement-based grouting material and forms a The spatial mesh structure with smaller voids improves the flexural strength and flowability of cement-based grouting material and reduces the dry shrinkage,thus significantly improving the hightemperature stability of SFPM.The research results can provide technical support for the promotion and application of infilled semi-flexible pavement. |
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