Research On Design Method And Application Of Asphalt Overlay On Old Cement Concrete Pavement

Based on the investigation of the diseases of the old cement concrete pavement,the reinforcement is carried out,and then the asphalt surface is paved,which is a design method that can effectively improve the road performance and structural performance.This paper focuses on the key technical problems of asphalt overlay on old cement concrete pavement,combined with the characteristics of urban roads in Xuzhou,using in-situ test analysis,physical and mechanical test,indoor trabecular model experiment,algorithm prediction,field industrial test and other technical means,studies and obtains the strength conditions and prediction methods of asphalt overlay on old cement concrete pavement,and puts forward some suggestions The optimum overlay structure is obtained.The results are as follows:(1)Based on the field investigation of 10 old cement concrete pavements in Xuzhou City three representative roads are selected,and detailed investigation and core drilling sampling are carried out.18 test pieces are made,and the residual strength of roads with different characteristics and disease degrees are obtained.The disease is analyzed,and the disease modes and causes of old cement concrete pavements are expounded,which provides reference for the development of old cement concrete pavements The reasonable thickness design method provides the basis.(2)The ideal point method is used to establish the old cement concrete pavement quality evaluation model and the Delphi method is used to establish the evaluation matrix first,and then determine the index weight.This evaluation method ensures the reliability of the evaluation grade.The ideal point method is used to establish five boundary values of 0,8.44,14.98,22.2,31.59,which are divided into five sections,and the old cement concrete road is divided into five evaluation grades The three roads and Quanxin road are evaluated and verified,which provides the basis for the paving of asphalt pavement on Quanxin road.(3)Based on the analysis of the residual strength of the old cement concrete pavement the thickness of asphalt overlay glass fiber grid and anti crack paste four factors and five types,11 working conditions and 33 model specimens the most reasonable design thickness of asphalt overlay on the old cement concrete pavement and the method of preventing reflection cracks are obtained which can provide reference for the overlay of Quanxin road Asphalt pavement provides the basis.(4)Using FLAC3D5.0 software,aiming at 12 kinds of working conditions,from the elastic model,plastic model and fracture model progressive layer by layer,the formation of reflection cracks on the old cement concrete pavement after paving asphalt surface is studied.With the improvement of concrete strength,the width and height of the plastic zone of the structure under the same overlay are gradually reduced,and with the increase of overlay thickness,Under the same concrete grade,the width and height of plastic zone decrease gradually,and increasing the thickness of overlay has more obvious effect on reducing the plastic zone at the bottom of old concrete pavement.(5)According to the evaluation model established by the ideal point method,the old cement concrete pavement of Quanxin road is investigated and evaluated.The score is 8.99,the evaluation grade is good,and it has the condition of paving asphalt surface.Through the analysis and Research on the diseases of Quanxin Road,this paper puts forward the targeted reinforcement method and puts it into practice,improves the design method of asphalt overlay of Quanxin Road,and further verifies the reliability and rationality of the design method through the specific implementation.