Exploring Relationships between Summary Resilient Modulus,California Bearing Ratio,and Light Weight Deflectometer Modulus for Unbound Coarse Materials in Idaho

Mechanistic–empirical pavement design (using AASHTOWare Pavement ME Design software) incorporates inputs at three different levels (i.e., Level 1, Level 2, and Level 3). Level 1 input is preferred over Level 2 and Level 3 in AASHTOWare Pavement ME Design software. Level 1 inputs are project- or job-specific, and are obtained through direct measurements or laboratory testing. Level 1 input measurements, such as the resilient modulus (M_R), might require additional resources to those required for Level 2 inputs. Many transportation agencies develop Level 2 inputs, which are more region-specific. For unbound materials, M_R is considered one of the fundamental material properties. Measuring M_R through laboratory testing requires advanced equipment and trained technicians, and the test is time-consuming. This study is an evaluation of the correlations between the resilient modulus of commonly used unbound materials in Idaho and the California bearing ratio (CBR) to develop Level 2 inputs. In addition, the recently introduced light weight deflectometer (LWD) modulus was correlated with the resilient modulus. The results of this study demonstrate a good and promising correlation between resilient modulus and LWD modulus, and a fair correlation between resilient modulus and CBR.