| August 01, 2009 |
A guide to understanding crack types, their causes and how to handle them.
Cracking is the bane of pavements, whether of asphaltic concrete or portland cement concrete. Asphalt pavement can crack from the top down and from the bottom up. It can alligator-crack, longitudinalcrack, thermal-crack, and fatigue-crack. Concrete pavements expansion-crack, D-crack, transverse-crack, fault and even blow up under thermal stress. And both asphalt and concrete overlays reflection-crack. While the hot-mix asphalt (HMA) establishment long has been focused on rutting — also called pavement deformation — cracking also forms such a threat to asphalt pavements that research on both rutting and cracking took the lion’s share of funds for the Strategic Highway Research Program (SHRP). The program was a five-year, $150 million research effort, mostly funded by the states, that was completed in 1993. Although, its principal product was the current Superpave system of design specifications, cracking was studied intensively.