Deflection-Based Field Testing for Quality Management of Earthwork

US Transportation Collection2018PDFTech ReportTirado, CesarFathi, AriaRocha, SergioMazari, MehranNazarian, SoheilUniversity of Texas at El Paso. Center for Transportation Infrastructure SystemsTexas Department of Transportation. Research and Technology Implementation OfficeUnited States. Department of Transportation. Federal Highway AdministrationTexas Department of Transportation. Research and Technology Implementation OfficeTexasUnited StatesCompactionDeflectionDurabilityEarthworkField testsPavement layersQuality assuranceQuality controlSpecificationsStiffnessTest proceduresFHWA/TX-19/0-6903-1, 0-6903-010-6903FinalTexas Department of Transportation (TxDOT) current practice for field compaction quality control and acceptance for base, subbase and soil layers is to determine the compacted density and sometimes moisture content by nuclear density gauge (NDG). TxDOT has also considered several stiffness-based devices to replace the NDG because stiffness parameters are more relevant to pavement design. Since spot tests cannot represent the uniformity of the compaction in a continuous manner, less stiff areas can be easily missed. For design-build projects an additional challenging step is the design verification. The current process based on laboratory resilient modulus tests is tedious and marginally representative of the in situ properties. Even though modulus-based nondestructive testing (e.g., with falling weight deflectometer (FWD), light-weight deflectometer (LWD) or dynamic cone penetrometer (DCP)) can be conceptually considered as a straightforward solution to this problem, a recent National Cooperative Highway Research Program (NCHRP) study has shown the level of detail that is needed to consider for obtaining meaningful values from the modulus-based devices. This research study has been carried to develop procedures and specifications to improve the process of design verification of compacted materials to ensure quality, performance and durability using a combination of proof rolling with the intelligent compaction rollers and deflection-based devices and to identify less stiff spots, to achieve uniformity, of compacted geomaterials.140