|M.Sc Student||Motola Yael|
|Subject||A Study of the Effect of Shear Stress Reversal on the|
Behavior of Asphalt Concrete
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Emeritus Jacob Uzan|
This thesis presents a comprehensive study of the effects of shear stress reversal on the behavior of asphalt concrete, specifically with respect to the resulting deformation and damage. The study consisted of a series of simple shear tests in a cyclic loading. The tests were performed without stress reversal (consistent with conventional methods of testing) and with stress reversal, as obtained from traveling vehicle's wheels. The purpose of the tests was to measure the damage and healing characteristics of the material. The difference in the damage caused to the material in the two tests was examined. The simple shear tests included two types of tests, frequency sweep tests and trapezoid loading tests. The frequency sweep tests were carried out before the trapezoid loading tests, after 20,000 cycles of trapezoid load testing and after a few days of rest. The load in the frequency sweep tests did not cause any damage to the material. The damage to the material after 20000 load cycles was measured in two ways:  by the frequency sweep tests, according to the ratio between the shear modulus that was obtained from the tests before and after the trapezoid loading and  by the trapezoid loading, according to the ratio between a visco-elastic shear strain that was calculated from a visco-elastic model without damage and the visco-elastic component of the shear strain that was obtained from the tests. The damage measurement that was obtained from the tests with stress reversal was approximately two times greater than the damage that was obtained from the tests without stress reversal.