Super-Accelerated Testing of Flexible Pavement with Stationary Dynamic Deflectometer

The Texas Department of Transportation (TxDOT), in partnership with the Center for Transportation Research, has implemented the Texas mobile load simulator (TxMLS) as a tool for accelerated testing of in-service pavements. Although the TxMLS has been used successfully to test in-service pavements in the Yoakum and Fort Worth districts, the fact that only one TxMLS machine exists limits the number of accelerated pavement tests (APT) that can be performed. Therefore, TxDOT is evaluating a modification of the rolling dynamic deflectometer (RDD) for use as a super-accelerated pavement tester. In this application, the truck-mounted dynamic loading system is operated in a stationary mode, with the loading rollers and rolling sensors of the RDD removed from operation. The servohydraulic actuator is used for application of harmonic loading to a wheel footprint on the pavement surface. Hundreds of thousands of load repetitions are applied in a matter of hours; hence the designation as super-accelerated testing. This stationary dynamic deflectometer (SDD) is being studied as a possible tool for use in expanding TxDOT’s APT program. The SDD may allow TxDOT to increase, in a cost-effective manner, the number of accelerated tests that can be performed. Preliminary tests have been performed with the TxMLS and SDD on two different pavement recycling strategies constructed on the northbound and southbound lanes of US-281 in the Fort Worth District. That the same conclusion was reached about the relative performance of the test sections with both machines indicates the potential usefulness of the SDD.