Influence of fly-ash based geopolymer additives on the preliminary properties of cold asphalt mix

Cold asphalt mix (CAM) offers a promising alternative to traditional hot mix asphalt (HMA) for pavement construction. Production and compaction at ambient temperatures result in a reduction in energy consumption and emissions. Despite these benefits, CMA mixtures exhibit inferior mechanical properties, including reduced early-life performance and increased porosity. Geopolymer is a new green technology that was developed in the construction industry. Geopolymers are produced using alkali solutions and alumina-silica precursors. This study focuses on the influence of the NaOH/ Na₂SiO₃ ratio and alkali solution/fly ash ratio on the strength of CMA. The molarity of the alkalisolution was fixed at 5 molars, then Marshall specimens for various mixtures were prepared at different NaOH/ Na2SiO3 ratios and alkali solution/fly ash ratios; later, specimens were left for 6 days at lab temperature and cured for 24hr at 40°C. Preliminary evaluation properties included conducting Marshall characteristics, i.e., stability, flow, and Marshall stiffness, and volumetric properties by bulk density. The results revealed that the best alkali solution/fly ash ratio and NaOH/ Na₂SiO₃ ratios are 0.65 and 1, respectively. As a result, it’s worth saying that geopolymer upgraded CMA to significant strength.