Forensic investigation of failed airfield test pavements

Abstract

Field and laboratory forensic studies were conducted to investigate the failure mechanisms of four different flexible test pavement sections at the Federal Aviation Administration's National Airport Pavement Test Facility (NAPTF), a state-of-the-art full scale pavement test facility dedicated solely to airport pavement research. The first set of test pavements constructed at the NAPTF included a total of nine test sections (six flexible and three rigid) built on three different subgrade materials: low-strength, mediumstrength, and high-strength. All test sections, except the high-strength test sections, were subjected to simulated repeated aircraft loading until the test sections were deemed to be failed. After the completion of traffic testing, trenches were dug in each of the flexible test sections to conduct post-traffic investigations into the failure mechanism of the pavement structures. Forensic tests conducted on the pavement component layers during trenching included CBR, in situ densities and moisture contents, and Dynamic Cone Penetrometer (DCP) tests. Heavy Weight Deflectometer (HWD) tests were conducted on the test sections before the trenches were dug. This paper focuses on trench investigations conducted on low-strength subgrade test sections. In the low-strength subgrade test sections, rutting was observed in the AC layer, unbound base and subbase layers in both the traffic paths. Shoving occurred in the AC layer.