Rheological properties of bitumen containing nanoclay and organic warm-mix asphalt additives

Abstract

In recent years, utilization of warm mix asphalt (WMA) proven to be an environmental way for reducing carbon dioxide emissions in the production and laying process of asphalt mixtures by decreasing the mixing and compaction temperatures. On the other hand, increasing traffic volumes cause asphalt pavements exposed to higher stresses, which could lead to premature distresses. In order to improve the resistance to distresses and alleviate the drawback of WMA mixtures, modification of the bituminous material has grown significantly. In this research, Sasobit as a warm mix asphalt additive and nano-montmorillonite k10 as a bitumen modifier used to modify the 60/70 and 40/50 pen-grade bitumen. The contents of Sasobit were selected are 0%, 2.5%, 3.5% and 4%, while for nano-montmorillonite k10 these percentages are 0%, 2.5%, 3.5% and 5% (by weight of pure bitumen). The objective of this study is to investigate the effect of additives on the conventional and rheological properties of bitumen. To achieve this goal, conventional tests, rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR), and direct tension tests were conducted to characterize the properties of pure and modified bitumen. The results indicated that Sasobit has a negligible effect on fatigue and low temperature cracking resistance. Conversely, when increasing the amount of nano-montmorillonite k10, these properties were improved. The results showed that nano-montmorillonite k10 improves the rheological properties of bitumen and reduced drawback effect of Sasobit, especially in low temperature cracking performance.