Standardization Of Fatigue Characteristics Of Cement-treated Aggregate Base Materials Under Different Stress States

Low liquid limit clay has the characteristics of low liquid limit,small plasticity index,low CBR value and strength,poor water stability,and difficult to compact during construction.If it is directly used as a road bed and a base layer to build a filler,it may cause different degrees of disease on the roadbed due to insufficient stability and strength.Therefore,How to improve the characteristics of low liquid limit clay to meet the technical standards of the roadbed and subgrade,further research was needed.This paper is aimed at the problems in the reconstruction project of the North Wudu to Wugang junction of the G240 Baotai Line(formerly S220 Seven Ant Line)in Luohe City,Henan Province,the improved scheme and road performance of improved low liquid limit clay as roadbed and subbase filling materials were systematically studied,and the rationality of the verification scheme is verified by the paving and testing of the test section.The main work and research results of the thesis include:Through the soil test such as screening test,boundary moisture content test,compaction test,CBR test and unconfined compressive strength test,low liquid limit clay in this area were systematic test and analysis.Through the compaction test,CBR test,expansion ratio test,unconfined compressive strength test and rebound modulus test,the variation of key indexes of lime-modified soil with different lime content was analyzed,and the lime-modified soil road performance with different lime content was analyzed and compared.The research shows that the optimum moisture content,CBR value and unconfined compressive strength rebound modulus of lime-modified soil increase with the increase of lime content,and the maximum dry density and expansion ratio decrease with the increase of lime content.According to the variation law of each test result,the recommended value of lime optimum amount of lime in the project is given 6%.The feasibility of this study using different improved schemes as subbase materials was introduced,and the shortcomings of single lime and cement improvement schemes were analyzed.Through the unconfined compressive strength test,dry shrinkage test,splitting strength test and compressive rebound modulus test,the road performance of cement-lime comprehensive stable soil base material with different mixing ratios was tested.According to the test data,the best mix ratio of the base material of the project is given as cement:lime:soil=4:6:90.According to the recommended value of the lime content in the road bed and the recommended ratio of the base mixture ratio,the pavement of the test section was carried out,and the test section was tested.The test results show that the improved plan of therecommended value meets the design and specification requirements.