Rheological Study of Sulphur Modified Bituminous Binder

Abstract

The characteristic performance of asphalt concrete pavement always depends on the properties of
bitumen, volumetric properties of asphalt concrete mixtures and external factors such as
environment and traffic volume. Bitumen is a visco-elastic material where the temperature and
rate of load application have a great influence on its behaviour. Conventional bitumen binder is
exposed to a range of loading and atmospheric weather conditions; it is brittle in cold weather
and soft in a hot environment. Within pavement layer higher traffic volume produces high stress,
which is one of the main causes for pavement distress. The most serious distresses associated
with flexible pavements are Fatigue cracking and permanent deformation. These distresses
reduce the service life of the pavement and increase the cost of maintenance. There are different
solutions to reduce the pavement distresses such as using asphalt additives or by adopting new
mix design. Asphalt additive is known to give the conventional bitumen better engineering
properties as well as it is helpful to extend the life span of asphalt concrete pavement.
In this work an investigation has been to use commercial sulphur available in local market to
modify the conventional bitumen and attempt has been made to study the rheological properties
of the modified binders prepared with different sulphur contents and at different mixing
temperatures. This helps to understand the influence of modifiers on the rheological properties
and fatigue resistance with the aim of preventing fatigue cracking in bituminous pavement. The
conventional bitumen VG 30 viscosity grade was used in this work, modified with sulphur at five
different modification levels namely 2%, 3%, 4%, 6% and 8% by weight of the bitumen. The
rheological properties for asphalt binder were performed using a dynamic shear rheometer
apparatus.
It is observed that the addition of 2% sulphur with VG 30 bitumen, prepared at 100⁰ C
temperature results in the optimum rheological properties. Also the effects of aging on the
rheological properties of bitumen and modified binder have been studied. It has been observed
that the modified binders considered in this investigation satisfy the rutting and fatigue cracking.