10 Sep 2025

Evaluation of the Plate Load Test for Design of Rigid Airfield Pavements Using Various Plate Sizes

Abstract: This report addresses the state of knowledge of the plate load test and modulus of subgrade reaction (k), industry’s desire to simplify the plate load test, and the effect of the k-value on rigid pavement design. The report traces back the theory behind the k-value over 150 years to evaluate the current state of knowledge. A total of 144 plate load tests were executed on three subgrade materials under varying base course thick-nesses. Plate load testing was designed to evaluate various plate sizes and testing standards (e.g., the military standard CRD-C 655-96 and the ASTM International [commonly called ASTM] standard ASTM D1196-21). By measuring plate load tests on varying base course thicknesses, field-measured effective k-curves were developed. Overall, results show that kASTM was higher than kCRD. Although a smaller plate setup produced similar results, additional variability was introduced when using smaller plates. The results of the field data imply that the current effective k-curves underestimate the global stiffness contribution provided by the base layer. Findings suggest the analytically generated effective k-curves validate the measured k-values in the field.