Importance of Invasive Measures in Assessment of Existing Pavements

Abstract

Countless miles of aged interstate highway pavement in the United States and significant expenditures associated with reconstruction highlight the importance of cost-effective rehabilitation measures. However, the prescription of ill-posed rehabilitation strategies due to improper assessment can be costly. This paper details a forensic investigation of a 22.5-km (14-mi) stretch of interstate highway in Oklahoma, consisting of multiple asphalt concrete (AC) overlays accumulated over a 40-year period. A thorough nondestructive investigation was carried out using falling weight deflectometer testing and ground penetrating radar. This was followed by a detailed invasive investigation involving coring, drilling and sampling, laboratory testing, and trenching. The pavement profile deduced from nondestructive test results alone failed to reveal a significantly weakened subsurface AC layer that was clearly revealed during invasive testing. Mechanistic analysis of the perceived pavement and actual pavement profiles reveal a significant difference in fatigue life. The reliance on nondestructive testing alone for pavement analysis and rehabilitation design would have been in significant error.