Determining the Resilient Modulus and Dynamic Poisson's Ratio of Asphaltic Conrete

Abstract

<p>A theoretically sound and practical method of flexible pavement design remains one of the most needed, though widely unappreciated, aspects of transportation engineering. Papers presented at the Third International Conference on the Structural Design of Asphalt Pavements in 1972 greatly increased the awareness of design engineers of the testing problems involved in this field. The generated interest in rational, as opposed to empirical, flexible pavement design approaches brought about a pressing need for material characteristics for use in available theoretical modes.</p> <p>This study involved the development of laboratory equipment capable of providing values of resilient modulus, MR, and Poisson's ratio, v, of asphalitic concrete specimens. These properties are required as input for elastic layer analyses of flexible pavement systems. It was recognized that the developed equipement must be capable of providing reliable results at similar costs to conventional Marshall or Hveem tests, and should be adaptable to realistically simulate site conditions. It is considered that the equipment described herein satisfies these conditions.</p> <p>Test results on polymeric calibration samples compare favourably to those obtained during previous work on the resilient modulus of asphalt mixes. The testing program identified temperature, asphalt content and aggregate type as parameters that affect the resilient modulus. A future phase of this study onvolves a more comprehensice testing program in these areas, in addition to studying the effects of confining pressure and stress levels on material properties using equipment suggested from this initial testing program.</p> <p>Comparative design studies using available theoretical methods and generated stiffness parameters indicate possible cost savings as a result of thickness requirements for pavement systems comprised of mixes with higher MR values. Conventional empirical approaches do not permit similar thickness reductions for higher quality (strength) mixes.</p>