Field response and dynamic modeling of an asphalt concrete pavement section under moving heavy trucks

TL;DR: In this paper, an asphalt concrete section on a test track in the PACCAR Technical Center in Mount Vernon, Washington, was instrumented with strain gauges at the surface and in pavement cores, and tested using a Falling Weight Deflectometer (FWD) as well as trucks at different speeds and tire pressures.

Abstract: An asphalt concrete section on a test track in the PACCAR Technical Center in Mount Vernon, Washington, was instrumented with strain gauges at the surface and in pavement cores, and tested using a Falling Weight Deflectometer (FWD) as well as trucks at different speeds and tire pressures. This paper presents results from the analysis of the field tests, including comparisons with theoretical predictions using SAPSI, a computer program for the dynamic analysis of asphalt concrete pavements by the linear viscoelastic layer theory and the finite element method. The results indicate that static analysis using statically back-ca1culated layer moduli seems to be sufficient in analyzing FWD field tests, despite the fact that static back-calculation using FWD (dynamic) deflections will lead to "stiffened" elastic properties. Ninety percent of the measured strains in October 1991 and all measured strains in June 1992 were within ± 10 percent of their calculated values, versus 70 percent within ± 20 percent error in February 1993. The September 28-29 1993 truck tests showed a significant effect of truck speed as well as tire pressure on the asphalt concrete pavement response; the peak longitudinal strain in the asphalt concrete layer decreased by as much as 40% when the speed of the vehicle increased from idle to 40 mph. The same decrease occurred when the tire pressure was reduced from 90 psi to 30 psi. The. SAPSI computer program did not predict the pavement's response to moving loads as well as predicting the response to stationary dynamic FWD loads: It predicts a decrease in strain amplitude of about 20 to 25% when the speed increases from idle to 40 mph. The September 3