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Research On Expansion Cracking Of Asphalt Pavement By Cement Stabilized Macadam Base

Posted on:2018-04-16Degree:MasterType:Thesis
Country:ChinaCandidate:J W WangFull Text:PDF
GTID:2322330536985055Subject:Transportation engineering
Abstract/Summary:PDF Full Text Request
The reflection crack of asphalt pavement caused by the dry shrinkage and temperature shrinkage of cement stabilized macadam base has been generally approved,widely studied,effectively prevented and properly solved out.However,in recent years,in the desert Gobi area and the hot climates,there has been a new kind of damage called expansion cracking of asphalt pavement caused by the expansion of cement stabilized macadam base in the high temperature,which affects the road performance and traffic safety seriously.According to the expansion cracking of asphalt pavement by cement stabilized macadam base found in Ejin Banner of Alxa League in Inner Mongolia,this study is conducted from the following aspects: Firstly,the author investigate the basic situation of Inner Mongolia Ejina,including hydrological,geological and meteorological,and monitor the temperature distribution of pavement structure layer.Therefore,a preliminary analysis is made to figure out the causes of expansion cracking of asphalt pavement by cement stabilized macadam base in the desert Gobi area and hot climates.Secondly,the thesis tests the expansion coefficient of cement stabilized macadam mixture by different gradation,cement dosage,curing period,sodium sulfate content.And the expansibility of cement stabilized macadam mixture is analyzed.Thirdly,according to the temperature distribution of the pavement structure layer,the ANSYS finite element model is established to get a further theoretical analysis for the expansion cracking of asphalt pavement by cement stabilized macadam base in the desert Gobi area and hot climates.Next,the effect of swell joint spacing,expansion coefficient and compressive modulus on the expansion cracking is studied,too.Fourthly,based on the experimental and theoretical analysis,the prevention and disposal measures has been proposed for expansion cracking of asphalt pavement by Cement stabilized macadam base.Finally,relying on the “CeDa first-class highway” and "Jingxin highway(from Bejing to Urumchi)",the thesis studies the effect of disposal and prevention for the expansion cracking by setting expansion joint in the base layer.Lots of investigations,experiments and theoretical analysis has indicated that the expansion of base layer under high temperature is the main cause of expansion cracking of asphalt pavement by cement stabilized macadam base in the desert Gobi area.Theexperimental results show that the larger the cement dosage is,the greater the expansion coefficient of the cement stabilized macadam mixture is.For several gradation recommend by the Standard,the C-B-3 gradation has the smallest expansion coefficient,C-B-2 gradation with a maximum coefficient of expansion,C-B-1 gradation is between the two,OGFC gradation with skeleton void structure is similar to C-B-1,and the larger the content of coarse aggregate in the mixture,the smaller the expansion coefficient is.According to ANSYS finite element analysis,axial compressive strength test and engineering experience,when the vertical expansion displacement of pavement is up to 10 cm or the maximum lateral temperature stress of the base layer is greater than the axial compressive strength,asphalt pavement by cement stabilized macadam base would be cracking.Therefore,the study suggests that an expansion joints should be set every 100~200m in the base layer.The expansion coefficient of the base mixture should be controlled below 1.5 × 10-5,and the compressive modulus should be below 2000 MPa.
Keywords/Search Tags:cement stabilized macadam base, arch cracking, expansion coefficient, expansion joint, compressive modulus
PDF Full Text Request
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