Research On The Anti-cracking Performance Of Cement Stabilized Gravel Layer Based On Waste Rubber Powder In Xinjiang Region

Cement stabilized gravel layer as a road base has been widely used in China’s road base due to its high strength,good integrity and other characteristics.However,cement-stabilized aggregates are prone to shrinkage cracks in the Xinjiang region.In order to improve the cracking resistance of cement aggregates in Xinjiang,this paper improves the grading of cement stabilized aggregates and incorporates a small amount of waste rubber powder to improve the cracking resistance of semi-rigid subgrade.A systematic study of the crack resistance of waste rubber powder cement stabilized aggregates was carried out as follows.(1)The apparent properties of the test raw materials were tested,and 30 purpose waste rubber powder was used as an external admixture for cement stabilized aggregates;two types of grading designs,skeletal dense and suspension dense,were determined through the construction design specifications.(2)The maximum dry density and the optimum moisture content of each group of proportional specimens were determined through the compaction test of cement stabilized aggregates with waste rubber powder,and the optimum moisture content of vibratory compaction was obtained to be lower than that of static compaction.(3)Based on the orthogonal test,the best proportion and forming method were selected based on the 7-day unconfined compressive strength and dry shrinkage coefficient as the reference index.The compressive strength and crack resistance of the cement stabilized aggregates with 5% cement admixture,1% waste rubber powder admixture,dense skeleton grading and vibratory compaction were obtained.(4)The scrap rubber powder cement stabilized aggregates and ordinary cement stabilized aggregates were tested at different ages for unconfined compressive strength,compressive resilient modulus,splitting,freeze-thaw and other mechanical tests as well as dry shrinkage and temperature shrinkage resistance tests.The results showed that the incorporation of waste rubber powder slightly reduced the strength of the cement stabilized aggregates and improved the durability and cracking resistance.(5)A test section was paved on the primary road in Wuqui section and the test section was followed up and observed.From the results of the observation and core survey,it can be seen that the waste rubber powder cement stabilized gravel reduced the number of cracks in the subgrade,increased the average spacing and significantly improved the crack resistance of the cement stabilized gravel layer in Xinjiang.(6)Finite element simulation of the waste rubber powder cement stabilized crushed stone subgrade was carried out to obtain the distribution of bending stresses in each structural layer and the maximum bending value through the combined effect of temperature and vehicle load,and to derive the optimum thickness of the waste rubber powder cement stabilized crushed stone subgrade.