PRESSUREMETER MODULI FOR AIRPORT PAVEMENT DESIGN

A relatively new tool, the pavement pressuremeter, was used at three airports in order to evaluate its usefulness in pavement design. Two of the airports had clay subgrades, one had a sand subgrade. The results of the pavement pressuremeter (PPMT) tests were compared to the results of cyclic triaxial (CT) or resilient modulus tests and of falling weight deflectometer (FWD) tests. In order to make the comparisons, five analytical models were adapted to the PPMT results. Four of the models were used to evaluate variations of the PPMT modulus with stress level, strain level, creep and loading cycles, and the fifth PPMT model was used to evaluate the accumulated strain in the soil.; The comparisons were conducted in two ways. The first comparison consisted of comparing the measured FWD deflections to the predicted FWD deflections using the finite element program ILLIPAVE and inputing selected PPMT moduli from the four models. The predicted CT deflections were found by inputing the design resilient modulus {dollar}Msb{lcub}r{rcub}{dollar} from the CT procedure established by the Waterways Experiment Station (WES). The second comparison was a direct comparison of the PPMT, CT and FWD moduli. The PPMT moduli came from the methods which resulted in the best predictions of the FWD deflections. The CT moduli came from the WES design procedure and the FWD moduli came from the backcalculation procedure used by Eres Incorporated, from Champaign, Illinois.; The testing phase for this study included: 17 cyclic triaxial (CT) tests on samples recovered from the three airport subgrades, 32 pavement pressuremeter (PPMT) tests in the base courses and subgrades of the three airports and 368 Falling Weight Deflectometer (FWD) tests performed on the pavements of the three airports.; The research revealed that, for the PPMT, the use of Kondner's hyperbolic strain level model 1/E = {dollar}a + bepsilon{dollar} yielded the best prediction for the FWD deflection for clays and that Janbu's stress level model {dollar}E = Ksb2{dollar} {dollar}left({lcub}Thetaover psb{lcub}a{rcub}{rcub}right)sp{lcub}n{rcub}{dollar} yielded the best prediction of the FWD deflection for sands. It also showed that the PPMT predictions of the FWD deflections were at least as good as the CT predictions. Therefore the PPMT can replace, advantageously, the CT.