The Research On The "White And Black" Technology For Renovation Of Old Street

Recently, with the rapid development of national economy and the increasing of capacity of highway and load-carrying capacity, pavements structure deteriorates severer and severer, more and more cement concrete pavements need rehabilitated. "White and Black"rebuilding can improve the utility performance of concrete pavements and prolong its service life. which has become one of the most important method of old cement concrete pavements with brilliant prospects.Investgation on understanding of many practices of asphalt over lay on old cement concrete pavement in our country and rehabilitation of Baixi road in Tongling city,this paper analyzes and studies the rehabilitation technology of old cement concrete pavement systematically,includes:(1)The assessment for structure characteristic of old cement concrete pavement.A correct assessment for pavementdistress and structuer characteristic of old cement concrete pavement before over lay is the stick point of preventing reflection cracking and guaranteeing the success of rehabilitat, including the evaluation of pavement structure performance and its serviceability.The former evaluation relatively-curved subsidence difference as its index. The latter evaluation uses pavement damage ratio PCI, road quality index RQI, slippery-resistance BPN and SFC as the indexes of evaluation.(2) The asphalt overlay design in rehabilitation of old cement concrete pavemen.Asphalt overlay design not only involves the distress,structure characteristic,traffic and environment of the old pavement, but also requites reasonable mechanics model,correct material parameter,effective measuer of preventing reflection cracking,and so on.So there is still not a matured design method up to now.This paper introduces several relatively matured design methods and puts forward some problems which require more study.(3)The prevention and contorl of reflection craking.In addition to load and temperature,the structure of road surface also has an impact on reflective cracks. There are primary kinds of measures of reflective cracking resistance at present: improving the performance of asphalt concrete overlay,dealing with the old concrete road front-panel and set middle layer of stress-eliminating, which include in detail the increment of the asphalt overlay's thickness,application of modified asphalt and reinforced materials,sealing and filling the stable cracks,breaking and stabilizing the old concrete pavement, application of SAMI and geotechnic fabric,application of geotechnic mesh and discontinuous bonding layer etc.(4) Stress analysis of asphalt overlay on the old cementc oncrete pavement with three-dimensional finite element method is described in this paper.