MONITORING PAVEMENT RESPONSE AND PERFORMANCE USING IN-SITU INSTRUMENTATION

The aim of this paper is to present the effectiveness of in-situ instrumentation in diagnosing pavement layer conditions under full-scale accelerated traffic loading (ATL). The test section is an in-service pavement in Jacksboro, Texas (U.S.). Multi-depth deflectometers (MDDs) were used to measure both permanent deformations and transient deflections, caused by ATL and Falling Weight Deflectometer (FWD) tests. Four different FWD loads of 25, 40, 52, and 67 kN were applied in close proximity to the MDDs at various traffic loading intervals to determine pavement conditions. It was found that the majority of rutting occurred in the newly recycled asphalt mix. The aged (>40 years) underlying base and subgrade layers contributed less than 30% to overall rutting. Only the top recycled asphalt layer underwent notable deterioration due to ATL. Up to 1.5 million axle repetitions, the test pad responded to FWD load almost linearly, not only over the whole pavement system but also within individual layers. However, under higher FWD loads, the percentage of total deflection contributed by the subgrade increased.