Forensic Studies: A Key Tool for Directing Future Research

Forensic studies are conducted in Texas when premature pavement failures occur. The purpose of these studies is threefold; firstly to identify the cause of the pavement problem, secondly to identify what actions the DOT should take immediately to minimize its impact and thirdly to identify changes to materials/design/construction practices or specifications which will eliminate this problem in the future. While conducting forensic studies TxDOT makes extensive use of non-destructive testing equipment. For flexible pavements air coupled high speed Ground Penetrating Radar (GPR) is a critical tool. The device can, at highway speeds, detect defects in both surface and base layers. GPR testing is followed by deflection testing and validation coring. Basic and advanced laboratory testing are also frequently required to fully diagnose problems. In this paper the nondestructive tools found most useful will also be described together with examples of recent forensic studies. The main focus of this paper will be to address the third issue described above that of avoiding problems in the future. In many instances forensic studies identify areas where future research studies are required. Examples will be given where the forensic study initiated a research project which provided products aimed at eliminating the problem. Examples of this include recently completed studies on minimizing the impact of sulfate heave and improving the crack resistance of asphalt overlays.