ROUND 1 TYPE II UNBOUND COHESIVE SUBGRADE SOIL PROFICIENCY SAMPLE PROGRAM

Strategic Highway Research Program (SHRP) Protocol 46, "Resilient Modulus of Unbound Granular Base/Subbase Materials and Subgrade Soils", was the specified procedure for laboratories performing resilient modulus tests on research samples of unbound cohesive subgrade soil obtained from Long-Term Pavement Performance (LTPP) field sites. P46 requires a test system that includes a triaxial pressure cell component, a closed loop electro-hydraulic repeated load component, and certain load and specimen response control, measurement, and recording components. Two elements of P46 testing were particularly important: verification that the system was calibrated and yielding reasonable results and a practical means of performing quality checks on a daily or more frequent basis. Worksheets, supporting data, analyses, final comments, and conclusions are presented.