Establishing the Light Weight Deflectometer as a Field Quality Indicator for Airfield Drainage Layers

Abstract: Drainage layers play a critical role in maintaining the long-term performance and stability of airfield pavement systems by rapidly removing infiltrated water and reducing pore pressures within base and subgrade materials. Current Department of Defense (DoD) and Federal Aviation Administration (FAA) guidance specifies material gradation, thickness, and separation requirements for drainage layers but lacks standardized field performance criteria to verify construction quality. Field acceptance testing is typically limited to grain-size distribution and density testing which are parameters that fail to capture in-situ stiffness particularly for open-graded, highly permeable materials where nuclear-density testing is unreliable. Consequently, quality control practices are not standardized and project-specific, often relying on the construction of trial test sections to establish reasonable compaction or placement procedures. To address this knowledge gap, small-scale airfield pavement test sections were constructed at the U.S. Army Engineer Research and Development Center (ERDC) in accordance with existing DoD guidance criteria to evaluate the Light Weight Deflectometer (LWD) as a field-based quality indicator. LWD testing provides rapid, repeatable measurements of surface modulus (Ev), which reflect changes in structural integrity and moisture response. Data collected before and after rainfall events, and during curing of stabilized drainage layers, demonstrated quantifiable stiffness variations associated with drainage-layer performance. The results indicate that establishing threshold LWD modulus values linked to drainage adequacy and construction uniformity could provide the foundation for performance-based quality control and quality assurance (QC/QA) specifications. This work aims to establish the foundational framework for developing practical performance-based specifications that could significantly improve the quality and reliability of airfield drainage systems.
Keywords: Airfield drainage layers; Light Weight Deflectometer (LWD); Modulus; Quality Control/Assurance (QC/QA); Pavement construction