Resilient Moduli of Flexible Pavement Materials

Abstract

<p> The behaviour of asphaltic concrete, granular base and subbase materials, and subgrade soils in repeated dynamic loading is best represented by their resilient moduli in rational flexible pavement designs. The recoverable, or resilient, strains in pavement structures due to repetitions of moving traffic loads can be predicted through the use of appropriate material parameters in analytical or numerical models of pavement response. It appears that the repeated-load triaxial test offers the most promising means of applying simulated field loading conditions to representative samples of flexible pavement components. This testing of laboratory or field prepared samples provides a good estimate of the material 1 s overall dynamic behaviour and the desired resilient modulus and Poisson's ratio for design analyses. The purpose of this research was to simulate field loading conditions for a range of typical Southern Ontario granular base and subbase materials by means of repeated-load, variable and constant confining pressure, triaxial tests using laboratory research equipment readily adaptable to regular design use. The pavement materials were characterized in a condition corresponding to optimum density and moisture content with repeated loadings representative of field stress conditions of 0.1 second pulse duration at a frequency of 20 cycles per minute. In addition to determining the resilient modulus and Poisson 1 s ratio for four basic conditions -unsaturated drained, unsaturated undrained, partially saturated drained, partially saturated undrained -the results were examined for significant trends. The characterization of typical base, subbase and subgrade materials for Southern Ontario, coupled with previous work on asphaltic concrete, allows the use of representative moduli for all flexible pavement components in Ontario pavement design systems such as OPAC. </p>