Effect of hot storage on engineering properties of polymer modified binders and asphalt mixtures

Abstract

Styrene butadiene styrene (SBS) is the polymer type most commonly used to manufacture polymer modified binders (PMBs). PMBs may need to be kept in a hot storage tank for an extended period of time because of adverse weather conditions or other uncertainties. Though PMBs show enhanced performance, a premature failure might occur in asphalt concrete during hot storage on exposure to a combination of heat and air. The aim of the current study is to examine the effect of hot storage on the engineering properties of PMBs and asphalt mixtures. SBS-based PMBs were stored in a storage tank at 180 °C up to 28 days in this study. It was estimated that more than four fifths the SBS polymer remained after long storage periods. There was a reduction in tenacity and elastic recovery test results, indicating that the degradation of the SBSpolymer could occur after a long period of hot storage time. The otherPMB test properties including toughness and storage stability did not vary significantly as the storage time was increased. Even though the SBS polymer in PMBs appeared to be degrading during storage, there was no change in the wheel tracking performance of the PMBs in asphalt mixtures. The cracking resistance obtained in semi-circular bend tests, by contrast, varied for the PMBs after hot storage. The results obtained in this study show that degradation of the polymer in a PMB during hot storage may not necessarily reduce the performance of asphalt mixtures.