The objective of this research is fourfold: (1) measure the dynamic modulus of commonly used Superpave and SMA mixes, (2) measure the resilient modulus values of two soils and two aggregate base courses that represent high and low values, (3) compare the measured moduli with Mechanistic-Empirical Pavement Design Guide (M-EPDG) level 3 default moduli for the subgrade and aggregate base material, and (4) evaluate the sensitivity of the M-EPDG to changes in materials moduli. A comparison was also made using the PerRoad Perpetual Pavement Design Software and the AASHTO 1972 Design Guide currently being used by Georgia Department of Transportation (GDOT) to determine differences in required structure for proposed new construction. Conclusions and recommendations based on test results obtained during the research are: (1) The M-EPDG level 3 default values for resilient modulus of both soil and aggregate materials are significantly higher than the actualvalues determined from laboratory test results. Use of actual materials properties and load spectra resulted in significantly greater structures being recommended than when level 3 default values were used for the M-EPDG design program. Based on these results GDOT is cautioned against using thedefault values built into the M-EPDG software. (2) The M-EPDG software was unable to design a satisfactory pavement structure at the 90% reliability level for the high traffic urban principal interstate arterial when poorsoil subgrade was used. (3) It is recommended that GDOT continue to use the 1972 AASHTO design procedures until the M-EPDG design procedure has undergone more thorough validation at the state level.
Abstract