Study On Road Performance Of Cement Fly Ash Stabilized Crusged Stone After Microcracking

In order to reduce the reflection crack of pavement and control the shrinkage crack of cement fly ash stabilized macadam base in the initial maintenance period(1～3days)effectively,this paper introduces the microcracking technology.Microcracking technology refers to the use of vibratory roller to roll and produce micro-cracks in the early maintenance of cement-stabilized base,in order to prevent the generation of long and wide cracks in the later stage with the increase of age.The initial strength of materials has decreased after microcracking of cement-stabilized base,but it will return to normal level gradually later,and it will not affect the normal use of the pavement and pavement life.The main factors affecting the mechanical behavior of cement fly ash stabilized macadam and its dry shrinkage properties after microcracking are mix structure type,cement dosage,fly ash content,microcracking time and microcracking degree.Therefore,it is necessary to study the variation of mechanical properties and dry shrinkage resistance of cement fly ash stabilized macadam after microcracking technology under the influence of different factors.The main contents of this paper are as follows:(1)Based on the microcracking technology and its mechanism,analying the main influence factors of microcracking technique,and the test scheme was proposed.The reasonable control of microcracking degree is the key of producing the ideal micro-cracks after microcracking.In order to achieve the effective control of microcracking process,the microcracking degree control model considering the coupling conditions of microcracking load,microcracking time and material characteristics was established based on two regression orthogonal combination design method.(2)The specimens with different microcrackings are prepared,laboratory tests on unconfined compressive strength,splitting strength and modulus of compressive resilience were carried out under different cement dosage,fly ash content,microcracking time and microcracking damage degree.The mechanical properties of cement fly ash stabilized macadam under different working conditions were studied systematically,the change rule of mechanical properties of cement fly ash stabilized macadam after microcracking and the optimum content of fly ash are summarized.(3)On dry shrinkage test,the effects of micro-cracking time and degree on the dry shrinkage characteristics of cement-fly ash stabilized macadam were studied under the premise that the mixtures structure type,fly ash content and cement dosage remained unchanged based on the research results of mechanical properties.