PARAMETRIC STUDY ON UNBOUND PAVEMENT MATERIAL USING CYCLIC TRIAXIAL TESTS

Abstract

Over the past two decades or so, a number of rational design methods have been developed for highways and air-field pavements. Existence of heaviour wheel loads makes a.. highway engineer to think in terms of fatigue of pavement materials. There are, several methods available for estimation of fatigue behaviour and modulus of ela-sticity of pavement materials under various condition. The method which simulates more to the field conditions in laboratory testing is the triaxial repeated loading test. In the present study, well graded granular material having maximum size 25mm has been selected for deter-mining the modulus of resilience , modulus of elasticity and permanent and reslient strain under various lateral confinement conditions. The proportioning of various ingredients of mix was determined by Rothfutch method. Small percentage of soil was added to above mix to impart little cohesion in order to retain the shape of sample without altering granular characteristics of the mix. Cylindrical specimens of 10 cm dia. and 20 cm. height were casted and kept open in air for drying for about 2 days. Three different confining pressure of 0.7, 1.4 and 2.1 kg/cm2 were selected as per the guide lines in the literature reviewed. For each confining pressure three different deviator stresses were selected for stress level ranging froM 13 to 58 percent. The sample were tested for unconfined, static and dynamic triaxial tests. The variation in the parameters of the pavement materials. in the study listed above under various conditions of testing have been reported along with the recommendations