Study On Road Performance And Construction Technology Of Large Thickness Cement Stabilized Macadam Base

For a long time,restricted by the paving thickness,the cement stabilized macadam base is constructed in layers in practice.The continuous state of layers is discontinuous,which is not satisfied with the continuous state of layers in the design process.The discontinuous state of layers reduces the bearing capacity of the complete base,which is unfavorable to the base.In this paper,based on the experimental study of the road performance in different interlayer States and the finite element modeling analysis of the mechanical properties in different interlayer States,the road performance and construction technology of the base course with large thickness of cement stabilized macadam are explored.The main contents of this paper are as follows:(1)investigation and analysis of the current situation of cement stabilized macadam base in China.(2)Raw material test and mix proportion design of cement stabilized macadam mixture.(3)Experimental study on road performance of thick base material,including the splitting strength,modulus of elasticity,flexural strength,compressive strength and so on.(4)Analysis of mechanical characteristics of different construction methods(layered,full thickness construction)of base course pavement.A three-dimensional finite element model is established to analyze the mechanical properties between the whole layer of cement stabilized macadam base and the layered construction base.(5)Research on construction technology of thick base course.The main conclusions of this paper are as follows:(1)In the laboratory test,three different interlayer bonding states are simulated,and the fully continuous interlayer bonding state is better.(2)The compressive strength of specimens in different interlaminar States was significantly different.When the age was 7 days,the strength of fully continuous specimens was 15.7% higher than that in semi continuous state and 18.2% higher than that in smooth state.The strength rule of specimens with different ages is the same.(3)The flexural strength of the specimens with different interlaminar States is significantly different.The flexural strength of the specimens with complete continuous state is 51.2% higher than that of the specimens with semi continuous state,and 73.5% higher than that of the specimens with smooth state.(4)Different interlaminar states affect the resilient modulus of cement stabilized macadam.(5)There is no significant difference in the splitting strength between different interlaminar states.This should be related to the way in which the splittingstrength applies the load.(6)Under the action of standard axle load,the mechanical performance of pavement structure with large thickness base course is obviously better than that with layered construction.The surface deflection is reduced by14.3%,and the bottom tensile stress of the base course is reduced by 7.3%;under the action of heavy load,the surface deflection of pavement structure with large thickness base course is reduced by 11.4%,and the bottom tensile stress of the base course is reduced by 13.0%.(7)Under the action of standard axle load,when the whole layer is constructed,the tensile stress index at the bottom of the layer is the same when the base layer thickness is 30 cm and the layer construction is 36 cm,that is to say,the whole layer construction can reduce the design thickness of the base layer.