Analysis Of The Mechanical Cause Of Longitudinal Cracking Of Cement Concrete Pavements

Owning to advantages of high strength, high stiffness and good durability, cement concrete pavements have been widely used in the road engineering in China. But the investigation results reveal that substantial cases of cement concrete pavements cracking failure occur during the design period, which does not manifest the advantages of concrete pavement, instead it causes the maintenance difficulties. At the same time, the results also show that longitudinal cracking as prominent failure modes in pavements.Therefore, to resolve these problems, analysis of mechanics cause about longitudinal cracking of cement concrete pavements has been carried out in this paper.Cement concrete pavement slab will generate the constantly changeable stress under the combined effect of the traffic load and the temperature gradient, in their design period. When the repeated stress reaches a certain number of times, concrete material will come to its fatigue life, and then lead to cracking failure in pavements.The cracking behavior of cement concrete pavements slab is developed in this paper. Load position has been selected in the central of slab along the transverse (normal driving position) by investigation on the distribution of wheelpath of the slab, to establish 3D pavement model by finite element software, and then analysis the distribution of stress and the cracking form of slab under the comprehensive fatigue effect of load stress and temperature stress. The results show that the slab tends to occur longitudinal cracking along the wheelpath zone on the transverse edge of the slab.The analysis basing on the result of field investigations and coring on cement concrete pavement demonstrates that the actual parameter values remarkably deviate from the design parameter values. Analysis of the impaction of parameter variation on pavement fatigue life and calculation of the fatigue life values under different structure combination has been performed. Analysis of actual pavements indicates that lower parameter values are the basic reasons of pavement fatigue cracking. Finally, regression relations between fatigue life and the pavements structure parameters are established, which can better estimate the fatigue life of the pavements.