Comparing Engineering Properties from Small Diameter Pressuremeter Tests to Nuclear Density Unit Weights and Lightweight Deflectometer Stiffnesses in Cemented Coquina Base and Sandy Subgrades

Abstract

Abstract Small diameter pressuremeter (SDPMT) equipment was developed and evaluated at four sandy embankment/roadbed sites in east-central Florida. These materials ranged from very loose to very dense. SDPMT tests were developed with the goal of supplementing or even replacing the nuclear density gauge (NDG) tests. SDPMT probes were placed in the pin holes made from NDG testing. Two probe lengths of 15 and 30 cm (6 and 12 in) were used, and two SDPMT testing procedures were used. One was the conventional incremental volume injection method and the second was a continuous injection process. Incremental tests were completed in about 15 min, whereas the continuous tests were completed in less than 1 min. SDPMT elastic moduli and limit pressures were obtained from 156 SDPMT tests. They were compared to dry unit weights from 96 NDG tests and 96 moduli from each of two lightweight deflectometer (LWD) models, one with digital load-deflection output and the other with input load and digital deflection output. One-hundred and twenty statistical models were developed describing the relationships between SDPMT, LWD, and NDG data. Linear, logarithmic, and exponential models were used. Ninety-three of the 120 models produced regression coefficients (R2) greater than 0.7, and 46 of the 120 produced R2 values greater than 0.8. Of the 40 models comparing SDPMT strength and stiffness to NDG dry unit weights, 12 or 30 %, produced R2 values greater than 0.8. Of the 40 models comparing SDPMT strength and stiffness to the Zorn LWD, 23 or 57.5 % produced R2 values greater than 0.8. Of the 40 models comparing SDPMT strength and stiffness to the Dynatest LWD, 11 or 27.5 % produced R2 values greater than 0.8. These models indicate that SDPMT strengths and stiffnesses are strongly correlated to NDG unit weights and LWD stiffnesses.