A STUDY ON VISCOELASTIC PROPERTIES OF MODIFIED BITUMEN IN NON LINEAR REGION

Abstract

This Report presents analysis on various studies made on the nonlinear viscoelastic behaviour of zycotherm modified bitumen binders. Most of the studies available are made mostly on the linear viscoelastic regions. The higher variation in stress-strain relationships occurs in the non-linear region and hence it is important to understand these regions and there is a need for more researches in this field. The conventional tests were carried out to determine the changes in properties of bitumen when zycotherm is added as a modifier. In this study the specimens were tested using a dynamic shear rheometer (DSR) at several temperatures and frequencies. It required to conduct all DSR tests at the same range of stresses, which is necessary for establishing the master curve for nonlinear viscoelastic materials. The stress levels for each test, at a given temperature and frequency, is to be normalized by the ultimate stress level of that test. The study was conducted to throw light into the rheological properties of bitumen and how it gets modified by the addition of binder as well as due to the effect of aging. The parameters such as the complex modulus and the phase angle were studied in depth and analysis were made on the variations of these parameters at different ranges of temperatures, frequencies and strains.