Study On The Index Of Old Cement Concrete Pavement Slab Bottom Void

Due to the rapid economic development,the cement concrete road in the "construction period" has been changed to the old cement concrete road in the "maintenance period".Judging the void condition of the slab bottom is an essential part of the maintenance work and an important evaluation index for evaluating the usage method,technology,Period and economy of the old cement concrete road in the maintenance period.Therefore,it is of great engineering significance and application value to accurately judge whether there is void at the slab bottom.In this paper,the causes of the old cement concrete pavement slab void,the void criteria of the detection void instrument,the investigation and evaluation of the old cement concrete pavement damage,the theoretical calculation of void and the combination of on-site detection tests are studied,and the void standards of different damage grades of the old cement concrete pavement are obtained and verified.The specific work content is as follows: 1.The causes of the old cement concrete pavement slab void were analyzed and the void analysis chart was established.According to the formation mechanism of old cement concrete pavement slab void and the surface diseases caused by void,the causes of void are divided into four categories and the cross section and plane analysis diagram of void slab are established to analyze the void state and evolution process.2.Comprehensive analysis of the existing plate bottom void detection instrument working principle,determine the accuracy of the judgment void method and void criteria.3.Determine the measuring point of the deflection value of the old cement concrete pavement slab bottom.Firstly,according to the different thickness of concrete slab and foundation modulus of the old cement concrete pavement,the deflection values of the middle and side of the plate,the Angle of the plate and the range of the edge-middle deflection difference and the angle-middle deflection difference of the plate are calculated.Secondly,investigate the thickness of concrete slab and the damage of the surface layer of the old cement concrete road to determine the different damage grade of the road surface..Finally choose according to different damage level five(money ditch road,shandong road,temple menand three road and south street,happiness DiaoTai)old cement concrete pavement,testing its joint load transfer capacity and deflection value activity and Angle of deflection and edge--deflection difference in scope,each road pavement actual situation,and west card the theoretical value and measured value correction,get the basis determine range.4.Determine the void removal standards for different damage grades of the old cement concrete pavement.5.According to the decided standards,Using Backman beam deflection meter and Falling Weight Deflectometer,the deflection values of the old cement concrete slab of Huashan No.2 Road at three points(slab center,slab edge midpoint,slab angle)were tested.The edge-to-middle deflection difference and angle-to-middle deflection difference were used to calculate the test results,and the degree of coincidence between dynamic and static deflection difference was analyzed and compared with the actual road void.The research shows that the old cement concrete pavement slab bottom void standard can better judge the actual road section void condition and the actual road surface layer needs to be investigated and evaluated in application.Combined with the detection data of Backman beam deflection meter and Falling Weight Deflectometer,the void evaluation of the old cement concrete pavement slab can be accurately carried out according to the void standard of different damage grades of the old cement concrete pavement slab proposed in this paper.