Laboratory evaluation of Sulphur Extended Asphalt Modifier

Flexible pavements with bituminous surfacing are widely used in India. The high traffic intensity in terms of commercial vehicles, overloading of trucks and variations in daily and seasonal temperature of the pavement have been responsible for the early development of distresses like ravelling, undulations, rutting, cracking, bleeding and shoving of bituminous surfacing. So it is essential to build a durable and long lasting road pavement. Designing a road with a strong bituminous base course like Dense Bituminous Macadam (DBM) can provide the load-bearing capacity needed to handle heavy axle loads. Strong base course also provides the load-spreading ability to relieve stresses and strains coming on to the subbase course and subgrade layers. Quality and quantity of binder have greater influence upon performance and durability of flexible pavements. Quality of binder may be modified by using certain modifiers such as polymer, crumb rubber, sulphur and use of these modifiers is dependent upon the type of construction, availability of material, equipment, and climatic conditions. The objective of this study is to evaluate the efficacy of Sulphur Extended Asphalt Modifier (SEAM) to improve the durability and rutting potential of a bituminous base course mix like DBM. Various laboratory tests like Marshall Stability, Tensile Strength Ratio, Retained Stability and Unconfined Creep were conducted on specimens prepared by two different types of binders namely asphalt of penetration grade 60/70 and another with 60% Asphalt + 40% SEAM. The results indicate that with the use of SEAM, reduction in asphalt usage can be significant.