Comparative Study On Crack-resistance Of Interlayer In Asphalt Overlay For Cement Pavements

With the rapid development of social economic construction in our country, thevehicle ownership is growing rapidly and road transportation presents the features ofheavier-industrialization, which leads to a variety of diseases to some extent oncement concrete roads. It is a simple and effective way to rehabilitate concretepavement with Asphalt overlay. However, how to control the development ofreflective cracking in asphalt overlay has been a big challenge in road engineeringfield. Although the application of cement stabilized macadam in cement pavementoverlay structure has been lasted for a long time, this material turns out to be moreeasily to engender reflective cracking due to material shrinkage and cracking.This paper focused mainly on the following several aspects:(1) Study on thecomposition, aggregate physical characteristics, the measurement of the optimummoisture content and the optimum content of admixtures, selecting of mixingprocesses and the corresponding experimental schematic design of the cementstabilized macadam and emulsified asphalt-cement stabilized macadam material (2) Aseries of laboratory experiment conducted to comparative study of the material basicmechanical performance (compressive strength, splitting strength, compressiveresilient modulus and shrink performance) for the cement stabilized macadam andemulsified asphalt-cement stabilized macadam material, the compressive resilientmodulus of cement stabilized macadam materials mixed with emulsified-asphaltreduced about40%, and a great improvement of reflection crack resistance washappened due to the improvement of shrinkage performance of the material itself.Comparing with cement stabilized macadam, the compressive strength and splittingstrength of emulsified-asphalt cement stabilized macadam after curing28daysreduced less than20%. According to the laboratory test results, the latter strength ofthis material can meet the code requirements. Therefore it is suggested that mixedwith the emulsified asphalt and should be applied to cement concrete pavementoverlay structure.(3) Based on the theory of fracture mechanics, mechanics analysisof all kinds of effect factors which can lead to cracking in the cement concretepavement overlay structure using ABAQUS finite element software, the stressintensity factors, loading stress and thermal stress are calculated. Result of the analysis show that this pavement overlay structure has certain effects on postponingthe expanding of reflection cracking.