Evaluation of olive pomace and SBS modified bitumen to the performance characteristics

This study investigated the applicability of olive pomace (OP) waste, a biomass waste, in bitumen modification. The OP modification was compared with styrene butadiene styrene (SBS) modified bitumen, which is widely used in asphalt modification, in terms of performance and cost. The OP and SBS binders were tested with conventional and rheological experiments. For this, modified asphalt binders were obtained by adding OP (wt. 4, 8, 15, 19, 25, 30%) and SBS (wt. 4, 4.5%) to pure B 50/70 penetration bitumen. The conventional test results of OP and SBS modified bitumen are close to each other, both modified bitumen decreased the penetration and temperature sensitivity of pure bitumen and increased the softening point. According to rheological test results, it was seen that the critical OP ratio was obtained from the 19% OP addition, and the critical SBS ratio was obtained from the 4% SBS addition and they exhibited the same performance grade. Then, for the hot mix asphalt (HMA) design, the optimum bitumen content was determined according to the Marshall method by using aggregate and B 50/70 pure bitumen, 19% OP, and 4% SBS modified bitumen. The effects of OP and SBS-modified bitumen on the mechanical properties of HMA mixtures were evaluated using Marshall stability tests. It could be said that OP-modified bitumen behaves like a more elastic solid at high temperatures, due to its lower penetration and higher softening point than pure bitumen. It has been observed that 19% OP additive provides an improvement, especially in rutting resistance, fatigue, and thermal crack resistance and 19% OP modified binder can be considered as an alternative to 4% SBS modified binder in general in terms of performance and cost. As a result, it is evaluated that OP can be used as a remedial additive in asphalt modification and contribute to the increase of pavement performance, and also that the damage of this waste material to the environment can be eliminated.