Heavy Vehicle Simulator aided evaluation of overlays on pavements with active cracks

Abstract

Conventional overlay life estimates are often invalidated by the reflection of existing cracks in a pavement through an overlay. This is attributable to a lack of understanding of the factors influencing relative crack movements and their mechanisms. Inadequate knowledge of the ability of overlay techniques to tolerated induced strains originating from the discontinuities in the existing overlay pavement also contributes to the problem. This paper identifies the factors and mechanisms and illustrates their effects by means of field data from actual pavements. The South African Heavy Simulator was also used to evaluate a variety of conventional and innovative asphaltic overlays on a severely cracked concrete pavement of which the mechanisms and extent of relative crack and joint movements were determined prior to overlay placement. The results of this testing programme are discussed with special emphasis on the eability of the overlays to inhibit reflection cracking. It is believed that the improved knowledge of the parameters involved in reflection cracking will contribute to more realistic prediction models and result in more cost effective rehabilitation strategies.