Research On Design Technology Of Asphalt Concrete Overlay For City Concrete Pavement

With the continuous development of urban construction,the cement concrete pavement can not meet urban transport and urban landscape demand.China has become the largest cement concrete pavement country with the world,and the pavement is more serious disease,so there is more pavement reconstruction project.The disadvantage of cement concrete pavement is also very obvious,such as the volume of structural fragility and sensitivity of temperature change.If the cement concrete pavement is tear down and reconstruct asphalt pavement,which will result in greater economic waste and environmental pollution.This article looks at the transformation of the existing concrete pavement,Cement Concrete Pavement Asphalt Overlay technology,and applied to practical engineering.First of all,the existing cement concrete pavement investigation and evaluation,and classification and classification of existing water concrete pavement damage to apparent damage and structural disease of two categories,analysis of the cement concrete pavement crack formation and development mechanism,The fatigue damage and water damage are the main factors for the formation of pavement cracks.The results show that the surface roughness,slip resistance,pavement crushing state,pavement load transfer,deflection,slab bottom,surface thickness standard,The comprehensive evaluation model of cement concrete pavement was established on the basis of the nine evaluation indexes of the elastic modulus,tensile strength and the equivalent elastic modulus of the top layer.Secondly,the formation mechanism and developmental mechanism of reflective crack in asphalt overlay layer are analyzed from two aspects of temperature effect and load effect.Three types of reflection cracks,tensile crack,smooth shear crack and tear shear fracture,are proposed.And the finite element method was used to analyze the stress of rubber asphalt stress absorbing layer,glass fiber grid,geotextile and no sandwich pavement structure of the stress,the results show that: the direct application of asphalt concrete structure of the overlay is maximum stress,stress and equivalent stress of the overlay joints were reduced by 58%,53% and 60%,respectively,when the SAMI stress absorbing layer was set up.The bonding strength of emulsified asphalt,SBR modified emulsified asphalt and gel adhesive was analyzed by pull-out test.The results showed that the bond strength of gel-type waterproof adhesive was 0.82,which was much higher than that of emulsified asphalt,SBR asphalt.Finally,based on the theory of finite element analysis,the structural forms of "asphalt overlay + rubber asphalt stress absorbing layer + gel type waterproof adhesive + old cement concrete pavement + foundation" were studied,and the thickness of asphalt overlay And stress absorption layer thickness on the stress of the load response of the situation,and the existing asphalt overlay design method,based on the use of COE balance method,AASHTO empirical method calculated for Kaixian Area cement concrete pavement structure for the thickness.The paper puts forward the pavement design model of 5cm rubber asphalt pavement and 1cm rubber asphalt stress absorption layer.The mechanics model and parameters of pavement are put forward through the analysis of three material strength theory.The finite element analysis method is used to analyze the effect of traffic load on the existence The results show that the pavement overlaying structure can meet the traffic load requirements,and the radius of the stress influence on the weakest position of the existing cement concrete pavement is about 2m in the concrete pavement of the existing cement concrete pavement.