COMPREHENSIVE EVALUATION OF LABORATORY RESILIENT MODULI RESULTS FOR GRANULAR MATERIAL

A comprehensive evaluation of nonlinear resilient modulus test results on granular materials is presented. A total of 271 test results obtained from 10 different research agencies were used as the data base. The main objectives of the study were to (a) determine whether typical M sub r relations exist for various granular materials; (b) develop a comprehensive summary of factors that affect the M sub r response and determine whether predictive equations or typical relations could be stated; and (c) investigate whether a correlation exists between laboratory-measured M sub r and laboratory-measured California bearing ratio (CBR) values. The results indicate that there appears to be an inverse relationship between K sub 1 and K sub 2 (M sub r = K sub 1 theta to the K sub 2 power) for all granular materials. Six unique K sub 1 and K sub 2 relations are proposed for six different granular material types (silty sands, sand gravels, sand aggregate blends, crushed stone, limerock, and slag). Predictive equations are developed to relate the primary variables that influence the M sub r response of six different aggregates (used by the Maryland State Highway Administration). The equations use bulk stress, degree of saturation, and percentage of modified compaction. Typical M sub r equations are also stated to reflect probable influences of the K sub 1 and K sub 2 values due to compaction and moisture for the Maryland aggregates. Based on an analysis of nearly 100 data pairs, a general, but variable, correlation was found between laboratory-measured M sub r and CBR values. However, the constant that relates these variables is a function of stress state. For typical bulk stress values anticipated in highway pavement structures, the coefficient (constant) value is significantly lower than the 1500-value suggested by Huekelom and Foster. (Author)