Effect of existing pavement condition and overlaying strategy on the reflective cracking resistance of asphalt pavement

Overlaying becomes more and more popular as a method to improve the driving quality and structural integrity of the pavement. The existing pavement condition needs to be evaluated when selecting the proper overlaying strategy. In this paper, the existing pavement condition of four field pavement projects was surveyed and the crack amount and crack pattern were monitored before asphalt overlaying and 1-2 years after the overlaying paving. It was found that thermal crack was initiated within two pavement projects, whereas the reflective crack was observed within other pavement projects with transverse cracks in the existing pavement. The potential factor that could induce the above field crack pattern difference was identified. Additionally, the Finite Element Method (FEM) analysis was conducted to study the effects of existing pavement conditions on crack propagation and the crack resistance of a new overlaying strategy. Results show that the J-integral of crack tip is increased and then decreased with the increase of crack length. The higher modulus of the existing layer leads to a larger value of J-integral while the aging effect of overlay contributes to delay crack propagation of the existing layer. The crack width of the existing layer has less effect on the J-integral at the crack tip of overlay. In addition, a new overlaying strategy is proposed to alleviate the reflective crack, in which multi-layer overlays are constructed and the geogrid is employed and placed between the existing pavement layer and the bottom layer of overlay, as well as other interfaces between any two adjacent overlays. Such a strategy is found to be effective in reducing reflective cracks by using simulative modeling.

Automated summary

Overlaying is a popular method to improve pavement quality. This study evaluates existing pavement conditions and crack patterns before and after asphalt overlaying. The findings indicate the presence of thermal and reflective cracks, with identified factors affecting the different crack patterns. Finite Element Method analysis shows that crack propagation and resistance are influenced by the modulus of the existing layer and the aging effect of the overlay. A proposed overlaying strategy with multi-layer overlays and geogrid is found effective in reducing reflective cracks through simulative modeling.