USING THE MULTIDESIGN DEFLECTOMETER TO EVALUATE TIRE PRESSURE EFFECTS IN FLEXIBLE PAVEMENTS . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

This paper describes observations made using Multidepth Deflectometers (MDD) in a full-scale experimental test pavement at the Waterways Experiment Station. A description is given of the MDD. Three pavements were instrumented and tested under Falling Weight Deflectometer (FWD) and truck loadings. Two fully loaded logging trucks were used; one with tire pressures of 276 kPa (40 psi), and the other at 758 kPa (110 psi). Passes were made at three speeds; 3, 16 and 32 Km/hr (2, 10 and 20 mph). Distinct tire pressure effects were noted in the higher vertical compressive strains in the subgrade for high pressure tires. The FWD data was used to backcalculate layer moduli for the experimental pavements. The MDD's performed well and have the potential of being an excellent tool for long term pavement monitoring. (Author/TRRL)