Modification of bituminous binders and asphalt mixtures by using nano materials

Due to having unique features like the higher active surface area and small spatial dimensions that give rise to the quantum effects, nanomaterials have made a solid ground in the research area. The introduction of nanomaterials into bitumen for enhancement of pavement in terms of its overall performance against commonly occurring distresses has been the topic of research for the last few decades. Within the scope of this study, three types of nanomaterials at their various proportions (percentage wise 2, 4 and 6 nano-Bentonite; 3, 6 and 9 nano-CaCO3, and 0.1, 0.2 and 0.3 nano-organosilane) were added into bitumen. A high-speed shearing mixer was employed to prepare the nanomodified bitumen samples. Fluorescence microscopy was utilized to observe the dispersion of nanomaterials in bituminous phase. For the preparation of hot mix asphalt (HMA), limestone was used. The objective of this study was to assess the influence of nanomaterials on physical and rheological properties of bitumen binders and also examine the mechanical behavior and performance of asphalt mixtures involving these nanomaterials. For this purpose, conventional and rheological tests were performed on base and nanomodified binders. For determining optimum bitumen contents, Marshall stability and flow test was carried out. Finally, the Modified Lottman test (AASHTO T283) was performed on compacted specimens to predict their performances against moisture susceptibility by obtaining the Tensile Strength Ratios (TSR). Based on the obtained results, nanomaterials were not very influential on the physical properties (penetration, softening point) of bitumen. However, they enhanced the high-temperature performance, aging resistance, storage stability and rheological properties when compared to the base binder. With nanomodification, asphalt mixtures resulted in lower optimum binder contents. The Modified Lottman test results declared that nanomaterials, especially nano-organosilane, can improve TSR values when compared with the control mixture. Keywords: Nanomaterials, nano-Bentonite, nano-CaCO3, nano-organosilane, fluorescent microscopy, modification, HMA, rheology, moisture-sensitivity