Study On Application Of Crack Resistant Cement Stabilized Crushed Stone Base

With the rapid development of China's transportation industry and the requirements of traffic load on China's road base,cement stabilized macadam base materials are more and more widely used in new construction and construction projects in China due to their large strength and rigidity.However,due to the fact that cement stabilized macadam is prone to cracks and poor water stability,it has attracted extensive attention from many researchers.In this paper,the research direction and ideas of the research on the basic layer of cement-stabilized materials at home and abroad are determined.Secondly,the design method of anti-cracking and compacting cement stabilized macadam is studied,and the forming method(vibration forming)and aggregate type are studied.,grading range,cement type,cement dosage,unconfined compressive strength are optimized,and factors affecting unconfined compressive strength are explored;then the compressive rebound modulus of cement stabilized macadam base is evaluated against the base layer.The impact of cracking performance and durability;finally applied the research results to the base layer of Nanlin Expressway and the base layer of Deshang Expressway to improve the construction technology of cement stabilized macadam base.(1)There are three main types of cement stabilized mixed materials.The traditional cement stabilized macadam is a suspended dense structure,and the anti-interstitial cement stabilized macadam studied in this paper is the result of compacting the skeleton,which is more than the traditional suspension compaction result.In other words,it has greater compactness and strength,and better crack resistance.(2)This thesis establishes the triple determination method of vibration forming parameters,and comprehensively studies the vibration molding parameters from three aspects: mathematical model calculation,indoor test analysis,indoor simulation test and actual compaction effect on site.The paper determined that the compaction parameters of the vibratory compactor were: static surface pressure 140 kPa;frequency 35 Hz;amplitude 1.4 mm;vibration forming time was 2 min.(3)The paper comprehensively analyzed the relationship between the optimum moisture content,the maximum dry density,the seven-day unconfined compressive strength,the splitting strength,the cement content and the fines content of the anti-cracking and compacting cement stabilized macadam mixture.And combines the construction situation of the construction site of Nanlin Expressway in Henan Province,which is commonly used in Henan Province.The reasonable pass rate of crack-resistant embedded-type cement stabilized macadam mixture of 4.75 mm should be controlled at about 30%;the crack-resistant and compacted cement stabilized macadam base has obvious crack resistance,and the average crack spacing is significantly larger than that of traditional cement.Stabilizing the gravel base,the number of cracks is significantly reduced.(4)Through the comparative study of the shrinkage performance of the crack-resistant embedded cement stabilized macadam and the traditional cement stabilized macadam base,the dry shrinkage coefficient of the crack-resistant cement stabilized macadam mixture can be reduced by about 15%-20%;The shrinkage factor can be reduced by about 10%-15%.It is recommended to use the maximum dry density of the vibration-molded test piece as the standard for the evaluation of compaction.The dry density on site is required to be not less than 98% of the maximum dry density of the vibration-molded test piece.A typical rolling scheme for a crack-resistant,compacted cement stabilized macadam base is recommended.