Effect of nano-silica on the chemical durability and mechanical performance of fly ash based geopolymer concrete

This study aims to examine the performance of fly ash/Nano silica-based geopolymer concrete (FANSGPC) to chemical attacks for the first time in literature. For this, an experimental study was carried out to achieve the goals of the study. A specified geopolymer concrete (GPC) with class F fly ash (FA) with and without Nano-Silica (NS) was produced for the investigation. Normal concrete (NC) was also prepared as a control specimen. The chemical attacks were achieved by sulfuric acid solution (H2SO4), Magnesium Sulfate (MgSO4), and Salt Water (NaCl) with the amount of (5%, 5%, and 3.5%), respectively. The main factors studied were the evaluation of mass, split tensile strength, compressive strength, and fracture toughness. The study results show that the performance of GPC, when exposed to chemical solutions for 30-days, was superior to NC concrete. This result is attributed to a more stable cross-linked alumina-silicate polymer structure formed in the geopolymer concrete. Furthermore, incorporating Nano-silica increases the durability of geopolymer concrete due to the formation of a high dense microstructure in geopolymer concrete. Keywords: Geopolymer Concrete (GPC), Fly Ash, Nano Silica, Chemical Attacks, and Fracture Toughness.