Development of Very Thin Overlay Systems (0-5598-S)

This project summary report summarizes the research performed in Texas Department of Transportation (TxDOT) Project 0-5598. This project designed and constructed very thin overlays that could be used as wearing surfaces. In this research, the newly developed upgraded overlay tester was used to ensure that proposed thin overlays would have superior resistance to reflection cracking. Researchers, using a special specification proposed by TxDOT, designed eight different crack attenuating mixes (CAMs). Very thin overlays, which met the proposed performance criteria, were placed on five major highways in Texas, with two on jointed concrete pavements. The CAM mix performance to date has been very good, and the use of the infrared bar or thermal camera inspection can help control temperature. Researchers recommend the combination of the Hamburg and overlay tester to produce a balanced mix design for thin overlays. The design procedure proposed in this project has several advantages over the volumetric procedure.