Characterizing Structural Performance of Unbound Pavement Materials Using Miniaturized Pressuremeter and California Bearing Ratio Tests

• Published in: Journal of testing and evaluation 2017-05, Vol.45 (3), p.818-834
• Main Authors: Shaban, A. M., Cosentino, P. J.
• Format: Article
• Language: English
• ISSN: 0090-3973; 1945-7553
• DOI: 10.1520/JTE20150371

Comparative analyses were implemented between the miniaturized pressuremeter (MPMT) test and the California bearing ratio (CBR) test to assess the capability of the MPMT stress-strain data for predicting structural performance of unbound pavement layers. Fifty-four MPMT tests and 108 CBR tests were performed on both base and subgrade soils in Brevard County, Florida. These comparative analyses were conducted in two stages. First, statistical correlations were established by comparing MPMT parameters with structural coefficients and structural numbers obtained from CBR data and the corresponding correlations. The results indicated that initial elastic moduli and limit pressures from MPMT correlate well with structural coefficients and structural numbers. Comparing them with results reported by AASHTO validated the quality of the correlation models. Secondly, finite element analyses were carried out to predict CBR as a function of MPMT data reduced to the strain-level model. The elastic moduli from the MPMT strain level model were input into the finite element simulation. To capture actual soil behavior, six strain levels were utilized during numerical simulations. For base course materials, strain evaluation points were selected at the top, middle, and bottom of the layer. For subgrade soils, strain evaluation points were selected at the top of the subgrade, 15 cm and 30 cm below subgrade surface. The results indicate that strain level moduli at the top of the base course layers provide the best CBR estimation, with the ratio of finite element CBR to measured CBR equal to 0.91. The results of subgrade show that strain level moduli determined at the depth of 15 cm below subgrade surface yield the best CBR prediction. The ratio of finite element CBR to measured CBR was 1.00.