A STUDY OF MODIFIED CHARACTERISTICS IN PAVEMENTS BY REPLACING BITUMEN WITH STYRENE BUTADIENE RUBBER (SBR) LATEX

Abstract: Flexible pavements with bituminous surfacing are widely used in India. Exponential increase in traffic, overloading of commercial vehicles and variations in temperatures have shown some limitations of conventional bitumen performance. Flexible pavements can be defined as the one consisting of a mixture of asphaltic or bituminous material and aggregates placed on a bed of compacted granular material of appropriate quality in layers over sub-grade. Bituminous surfacing develops distress symptoms like cracking, rutting, raveling, undulations, shoving etc, are been reported in flexible pavements. Bitumen modified with Styrene Butadiene Rubber (SBR) which is one of the most effective polymer additive offers a combination performance related to physical properties of the bitumen. SBR is an elastomer which is an important sort of synthetic rubber whose molecule structure primarily consists of organic compound Styrene and Butadiene chain. It plays an active role in improving the visco-elastic properties bitumen and also changes rheological behavior of bitumen by increasing the resistance of mixture against permanent deformations. This paper presents the experimental study on modification of Bitumen by the replacement of bitumen by SBR latex at 0, 3, 5, 7, 9% by the weight of bitumen. Various tests on bitumen like penetration test, softening point, viscosity test and ductility test are conducted on addition of SBR latex with bitumen and results are compared. Marshall Stability test is the one of the important test conducted to decide the performance of the bituminous mix. So, Marshall Stability test is conducted for various percentages of SBR latex and optimum % is determined. The properties of the mix evaluated by Marshall test are stability, flow, air voids (Va), volume of mineral aggregates (VMA) and void filled with bitumen (VFB). From this test optimum content of SBR to be added to bitumen is obtained. SBR latex is an easily available product and also economical.

Keywords: Bitumen, SBR latex, Marshal Stability test, visco-elastic.