Measuring Resilient Modulus of Granular Materials in Flexible Pavements

Abstract

A comparison study from the experimental results of the falling weight deflectometer (FWD) backcalculated modulus values, laboratory-measured resilient modulus values under field and laboratory conditions, and laboratory limerock bearing ratio values for granular materials in flexible pavements is presented. Based on the measured results, a case study was conducted to illustrate the use of laboratory resilient modulus for pavement design through the AASHTO flexible pavement design procedure. The results indicated that the average laboratory resilient moduli at optimum compacted conditions were 1.1 times higher than the average laboratory determined resilient moduli under in situ conditions. The FWD backcalculated moduli were about 1.8 times higher than the laboratory resilient moduli for the granular materials. The laboratory optimum moisture content was comparable to the field-measured in situ moisture content, although the average laboratory-determined maxi mum dry density was slightly higher than the average field-measured in situ dry density. The flexible pavement design could be based on the resilient modulus values found in the laboratory.