PERFORMANCE EVALUATION OF NANO-CACO3 MODIFIED BITUMEN IN HOT MIX ASPHALT (Paper 911)
The introduction of nanomaterials as modifiers into bitumen for enhancement of pavements in terms of their overall performance against common distresses have been researched and a considerable number of studies have been devoted to this topic, especially, during the last few decades. To ensure better performing and sustainable pavement design against the distresses caused by common factors such as; moisture susceptibility and high-temperature sensitivity of hot mix asphalt (HMA) components, modification is an inevitable option. In this laboratory study, Nano-CaCO3 is used to modify 50/70 bitumen with various proportions by weight of bitumen. A high-speed shearing mixer is employed to prepare the nano-CaCO3 modified bitumen samples. Fluorescence microscopy (FM) is utilized in order to get a good idea of Nano-CaCO3 particles dispersion in bitumen matrix. The objective of this study is to assess the influence of nano-CaCO3 on physical properties of bitumen by performing conventional and rotational viscosity tests. Additionally, Dynamic Shear Rheometer (DSR) is used to evaluate the rheological behavior. Critical high-temperature performance grading and performance under different loads (frequency) and temperatures are determined through complex modulus (G*) and phase angle (δ) values. Marshall stability and flow test is carried out on both control and nano-CaCO3 modified asphalt mixture. Finally, Modified Lottman test is performed and evaluation of their performances against moisture susceptibility is predicted by obtaining the Tensile Strength Ratio (TSR, %). Based on their performance results, asphalt mixture prepared with 6% Nano-CaCO3 modified bitumen exhibits comparatively good results.