Characterization of Aluminosilicate-Based Warm-Mix Asphalt Additive Using Experimental Techniques

In this study, an aluminosilicate-based water containing warm-mix asphalt (WMA) additive was developed using: sodium aluminate, tetraethyl ammonium hydroxide (TEAOH), montmorillonite (MMT K10), and water referred to as STEAM. Further, the STEAM additive and raw MMT K10 material were characterized using experimental techniques that included particle size analyzer (PSA), zeta potential, scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), thermogravimetric analysis combined with differential scanning calorimeter (TGA-DSC), and powder X-ray diffraction (XRD). The PSA and zeta potential results confirmed the exchange of sodium (Na+) ions and adsorption of water molecules (H2O) in the chambers of crystal structure. SEM images revealed STEAM particles to be larger and layered with fibrous look. The XRD images of MMT K10 and STEAM additive synthesized using one-step hydrothermal reaction showed similar high peaks at 2θ of 26.58°, and 12.24, 24.79°, which correspond to quartz and Kaolin, respectively, indicating no alteration in the crystal structure. The thermal analysis of STEAM additive confirmed the presence of water molecules (both physically and structurally bonded) with the loss in mass of about 10.52% between the temperature range of 80–260 °C similar to the mass loss in the commercially available standard zeolite A (SZA). Thus, the newly synthesized STEAM belongs to the group of synthetic zeolites. The approach taken in this study would help reduce the viscosity of asphalt binder during asphalt mixture production at lower temperatures making it suitable as a WMA technology.