Director of research and testing, National Crushed Stone Assoc., Washington, D.C.
Assistant professor, School of Civil Engineering, Georgia Institute of Technology, Atlanta, Ga.
The resilient response of highway materials has generally been considered to be a function of intensity, number, duration, and frequency of the stresses to which it has been subjected. To date, little research has been conducted to show the effects of these factors on the response of paving materials and from what has been done, the observed behavior varies from material to material.
The purpose of this investigation was to better define the effect of stress repetitions, load duration, frequency, and sequence on the resilient response of several crushed stone materials. Tests were carried out at two levels of density and moisture condition using a conventional triaxial cell. Repeated axial compressive stresses, as well as static ones, were applied under conditions of constant confining pressures. The resulting axial strains were measured.
Results from the tests indicated that the number of stress repetitions and stress sequence had little effect on the resilient behavior of granular materials. There was no evidence of a change in resilient behavior with changes in load duration or frequency. The significance of these findings is that the resilient response determined after 150 to 200 repetitions will provide a reasonable indication of resilient properties for a material subjected to a complex stress history. Findings also indicate that the response to stresses of different intensities can be measured in any sequence on a single sample. Furthermore, the response can be determined using either static or dynamic triaxial load tests.
Test procedures are formulated to provide the practicing engineer with a simple procedure for determining an estimate of the resilient properties of granular materials.
Paper ID: JTE10053J