Full-Scale Pavement Testing

Comparison Between Falling-Weight Deflectometer and Static Deflection Measurements on Flexible Pavements at the National Airport Pavement Test

Pavement surface deflection basins provide valuable information for the structural evaluation of flexible pavements. The pavement surface deflections are easily measurable compared to other responses, such as stresses and strains, and are the basic response of the pavement structure to the applied load. It is frequently used as an indicator of the load-carrying capacity of the pavement. Surface deflection measurements are rapid and nondestructive. Falling weight deflectometer tests and static load tests (using the National Airport Pavement Test Facility test vehicle) were performed on the multidepth deflectometers in the flexible pavements at the National Airport Pavement Test Facility before the start of traffic tests. The falling weight deflectometer is an impulse-type testing device that imparts a transient load on the pavement surface, and the duration and magnitude of the force applied is representative of the load pulse induced by an aircraft moving at moderate speeds. Static load tests are more representative of stationary or very slow moving aircraft. The National Airport Pavement Test Facility has nine pavement test items and 10 transition sections built on three different subgrades (California Bearing Ratio of 4, 8, and 20). There are six flexible pavement test items and three rigid pavement test items. The falling weight deflectometer tests were performed at load levels of 12,000, 24,000, and 36,000 lb. Static load tests were performed at load levels ranging from 12,000 to 60,000-lb wheel load. The falling weight deflectometer tests were performed on the top of the multidepth deflectometers, and the pavement deflections were measured by sensors mounted on the falling weight deflectometer equipment and the multidepth deflectometers. For the static load tests, the wheel was positioned over the multidepth deflectometers and the multidepth deflectometers measured pavement deflections. This paper summarizes the test results from falling weight deflectometer and static load tests performed on the six flexible pavements (three with conventional P-209 crushed stone base and three with P-401 asphalt stabilized base) at the National Airport Pavement Test Facility. A comparison of surface deflections for the six flexible pavements under falling weight deflectometer and static loading is presented.

Authors: Navneet Garg, Wayne H. Marsey