Performance Evaluation of Bituminous Concrete Mixes Modified with SBS Polymer and Warm mix Additive

The main objective of this study was to investigate the effect of SBS polymer and warm mix additive on the performance of bituminous concrete mixes. SBS polymer dosage was kept 3%, 5% and 7% and Zycotherm additive dosage was kept 0.1% for all binder mixes. Comparisons were made between Base bitumen, SBS modified bitumen and Zycotherm modified bitumen. For preparation of bituminous mixes, two different types of aggregates were used in this study i.e. Limestone and riverbed aggregate. To evaluate the performance of modified binder; Marshall Stability test, Indirect Tensile Strength (ITS) test and Rheological test were performed on binders and bituminous concrete mixes. From Marshall Stability test, SBS dosage of 5% was found to be optimum polymer content for both aggregate mixes. Maximum tensile strength for both the aggregate bituminous mixes was achieved at 5% SBS content. It was observed that maximum Marshall Stability was achieved when Limestone aggregates were used for preparation of bituminous mixes. Zycotherm additive does not have any significant effect on the properties of bituminous concrete mixes. However Zycotherm additive tends to decrease viscosity of binder at a temperature above 100 ˚C which will result in lower mixing temperature without compromising the performance of bituminous binder. Rheological test on different binders has shown that Zycotherm additive has very less affect on rutting resistance of modified bitumen. It was finally concluded that best results were obtained from Limestone aggregates using 5% of SBS polymer and Zycotherm additive has no significant effect on mechanical properties of mix