| Models have been developed to predict reflective cracking in flexible pavement overlays. For cracking, the combined effect of the cracked and uncracked area in the old pavement beneath the overlay is a factor that affects the development of cracks in the overlay. So far, this factor is not explicitly incorporated in the crack prediction models that have been developed. Therefore, there is a need to develop a model for the prediction of cracking in a pavement overlay that will incorporate this factor explicitly, making predicting cracking in pavement overlays more realistic and more applicable to Pavement Management Systems (PMS) applications such as crack distress predictions and the study of pavement reliability. A mechanistic-empirical approach will be adopted to develop the desired cracking model. The mechanistic approach is based on fracture mechanics. However, for the unavailability of some of the material properties, an empirical addition consisting of a stochastic form will be used for the development of the model. The use of the developed model for the study of reliability analysis and crack initiation is also presented. The results showed that the proposed model adequately predicted the observed cracking. The reliability study showed that when calculating the reliability of the overall pavement after overlay, the reliability of the overlay was not independent of that of the old pavement. In addition it was found that the reliability of the overall pavement increased with the increase in subgrade modulus, the increase of the overlay thickness, the decrease in construction variability, the decrease in annual rainfall, the decrease in the variation of the heating index, and the decrease in traffic loading. The proposed crack initiation methodology adequately described the time cracking first became visible in the overlay as compared to observed data. |
