This paper was presented at the `Strategic investment alternatives for sustainable roadway materials' session. The resilient (elastic) moduluse is the parameter that characterizes the elastic property of soils and granular materials. It is used in particular for sizing pavements and is the only parameter in th eAASHTO Guide for Design of Pavement Structures that characterizes the mechanical behavior of materials. Vehicle loading of pavement produces stresses that can affect the various layers of materials. Base and subbase materials with high resilient moduli allow for greater dissipation of the stresses transmitted to the soil support. Direct measurement of the resilient modulus of granula materials is done in a laboratory using a repeated load triaxial apparatus. A testing program was carried out at the Ministere des Transports du Quebec to determine the modulus for five MG-20 base materials of a different nature (granite, limestone, diabase, granitic gravel and Appalachian gravel) with six different particle size distributions falling within MTQ specification grading range. The tests were done on samples with varying water content as well as on frozen samples. The resilient modulus values are presented using the K-O Model in wish the constant k1 varies from 8,1000 to 11,500 kPa, and where the constrant k2 is equal to 0.6. The limestone material presented the highest modulus while granite proved to be the lowest. These results demonstrate that the resilient moduluse is a measure of the reaction of a material's skeleton or structure. One parameter that provides an indication of this structure is the void index; limestone had the lowest void index (closed structure) and granite had the highest (open structure). Because of this fact, limestone had the lowest permeability coefficient. Finally, the resilient modulus values proved to be independent of sample particle size distribution provided that a variance of 25% around the average value was tolerated. (A)
Abstract