Evaluating the Relationship between Permeability and Moisture Damage of Asphalt Concrete Pavements

Limiting the presence of water inside an asphalt concrete (AC) pavement can slow down the process involved in water diffusion, hydration, adhesion loss, and other mechanisms of moisture damage. In the past, numerous studies have been conducted on the topic of moisture damage and permeability, but very few studies have related permeability with moisture damage in AC. This study evaluates whether such relation exists. In essence, a field survey is conducted to identify a set of pavements (bad) that suffer from moisture damage and a set of pavements (good) that do not exhibit moisture damage. Field permeability tests and coring are conducted on the pavements. Laboratory permeability tests are performed on the field cores. An indirect tensile strength ratio (TSR) of wet- to dry-conditioned core samples is determined in the laboratory and used as a moisture damage potential parameter. Wet conditioning is performed by using a recently developed moisture-induced sensitivity test (MIST) device and a well-known AASHTO test method. Average field permeability of good pavements ($k=56\times {10}^{-5}\mathrm{cm}/\mathrm{s}$) is found to be less than the average field permeability of bad pavements ($k=87\times {10}^{-5}\mathrm{cm}/\mathrm{s}$). Both MIST and the AASHTO test method show a reduction in TSR value, which means moisture damage occurred during both conditioning methods. However, MIST showed a poor correlation, whereas the AASHTO test method showed a fair correlation between permeability and TSR. This study concludes that moisture damage is related to the permeability of AC.