Optimizing the combination of nitrile-butadiene rubber and styrene-butadiene-styrene for modification of asphaltic pavement

Modification of asphaltic pavements using nitrile-butadiene rubber (NBR) and styrene-butadiene-styrene (SBS) has been studied in recent years to improve pavement performance and durability while reducing waste from disposal of nitrile gloves. However, in previous studies, the uses of NBR and SBS were evaluated in isolation hence, their use in combination has not been considered. Therefore, in an attempt to use NBR and SBS in combination for modification of asphaltic pavements, hot-mix asphalt (HMA) samples containing varying dosages of NBR and SBS were prepared. Volumetric measurements and Marshall tests were conducted on the samples. Results suggest the incorporation of NBR and SBS at 6 and 5% dosages, respectively, by weight of the bitumen in the HMA, as the optimal combination. The combination led to the highest stability and lowest flow of the HMA, which contribute to the highest increase in stiffness hence highest improvement in strength.