Experimental Study On Asphalt Pavement Structure And Interlayer Performance Of Guangxi Overhaul Project

Modified asphalt mixture stress absorbing layer is a new type of road surface crack prevention material,which can effectively solve the technical problems of interlayer bond,the expansion of cracks,road surface water infiltration and so on between the asphalt overlay and the old cement concrete pavement slab.At this stage,the design method and technical performance evaluation system of the stress absorption layer of asphalt mixture are not perfect.In this paper,ANSYS finite element software was used to simulate the asphalt overlay structure based on the stress absorbing layer.The influence of the modulus and thickness of the stress absorbing layer and the asphalt overlay on the pavement stress were analyzed.Within a certain range,increasing the thickness of the asphalt overlay and the stress absorbing layer can slow down the generation of reflective cracks in the asphalt surface,beyond which the anti-cracking effect increases and decreases,and is not economically desirable.The reasonable thickness of the stress absorption layer is 2 to 3cm.Paving low modulus stress absorbing layer of asphalt mixture can effectively reduce the generation of reflective cracks,but not too low.In order to ensure the construction compaction and prevent the cumulative deformation of the pavement increases,it is recommended that the modulus of the asphalt mixture used in the stress absorbing layer be in the range of 400 to 600 Mp.Six kinds of AC-10 stress absorbing layer mixture grading with large differences in thickness were designed by using the power function.Their optimal asphalt-aggregate ratios were determined by four volume indexes of void ratio,void in mineral aggregate,asphalt saturation and gross bulk density.Secondly,with the SHRP climate model in the United States,the high temperature prediction of the stress absorbing layer with the depth of 10 cm below the asphalt pavement in Guangxi area was obtained.The maximum temperature of the stress absorbing layer in Guangxi is about 42.5 ~ 47.7?.And the dynamic stability of the six kinds of graded stress absorbing layer asphalt mixture is between 1561 and 2838 times at 60?,and the relative deformation at 60 min is in the range of 2.018 ~ 3.178 mm between.At 45?,the dynamic stability of the six kinds of graded stress absorbing layer asphalt mixture is between 7529 and 10151 times,and the relative deformation amount of 60 min is between 0.932 and 1.332 mm.The high temperature stability of a relatively coarse grading asphalt mixture is overall better than that of a relatively fine grading.Finally,through the permanent deformation prediction,it is concluded that the stress absorbing layer has little resistance to deformation,but it contributes little to the rut deformation of the whole pavement structure.Asphalt overlay with a low modulus of stress absorbing layer will not make pavement rut worse.Thirdly,the low temperature crack resistance performance of each grading of asphalt mixture was evaluated by splitting experiment,direct tensile test and bending test,and the fatigue performance of the mixture was evaluated by indirect tensile fatigue test.In this paper,the general grading and range of the asphalt mixture of AC-10 stress-absorbing layer suitable for Guangxi's high temperature and rainy weather are recommended,which is provided for the optimization of the grading of the aggregate direction.Finally,this paper studies the proportioning design and test road verification of the asphalt mixture of the stress absorbing layer,and puts forward feasible suggestions about construction variability control of the stress absorbing layer.