Laboratory Investigation of the Effect of Stone Mastic Asphalt Modified with SEBS Polymer and Cellulose Fibers on the Moisture Susceptibility

The use of fibers and polymers in asphalt mixtures leads to improved quality, higher lifespan, and lower maintenance costs by making mechanical, physical, and chemical changes. This results in eliminating or reducing the weaknesses of mixtures in the production, implementation, and service phases. In this study, the Stone mastic asphalt mixtures with the same gradation curve, but different additives are evaluated. In the first, second, and third groups of experiments, SEBS elasto-plastomer polymer (SEBS), SEBS elasto-plastomer polymer with cellulosic fibers (SEBS-CF), and SBS elasto-plastomer polymer with cellulosic fibers (SBS-CF) were added to the mixture in various weight percentages, respectively. Also, Stone mastic asphalt mixtures without any additives (SMA-S) and SBS-modified mixtures (SBS) as the most common modifiers were considered as the control mixtures. To evaluate the designated mixtures related to moisture sensitivity, several tests including saturated marshal, indirect tensile strength, resilient modulus, and drain down tests were applied. The results showed that the designated asphalt mixtures meet the requirements for the moisture sensitivity and resilient modulus tests successfully, and it is concluded that among these samples of mixtures, 4% SEBS has the best performance compared to other mixtures; it had even better performance than the SBS mixtures, which are the most common modifiers. Therefore, this issue can be a great help considering the advantages of this polymer over other modifiers to select and use it to modify asphalt mixtures among the mixtures although SEBS-CF had a higher percentage of optimum bitumen achieved less drain down, which shows that the bitumen of these mixtures has become more behaviorally stable due to modification with polymer and fiber at the same time.