Effect of Alkali Silica Reaction (ASR) in Geopolymer Concrete Final

Alkali silica reaction (ASR) occurs due to chemical reaction between hydroxyl ions in the pore water within the concrete matrix and certain forms of silica. This reaction could lead to strength loss, cracking, volume expansion and potentially failure of the structure. This manuscript reports findings of an experimental investigation of the inter-particle bonding between the reactive aggregates and the geopolymer matrix. Specimens were prepared using two Class F and one Class C fly ash stockpiles. Mechanical testing included the potential reactivity of aggregate and length change measurements as per ASTM standards. Petrographic analysis was conducted using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The results suggest that the extent of ASR reactions due to the presence of reactive aggregates in fly ash-based geopolymer concrete is substantially lower than in the case of OPC based concrete, and well below the ASTM specified threshold. The ability to utilize ASR-vulnerable aggregates in the production of geopolymer concrete products would increase the economic and sustainability appeal of this technology, potentially resulting in significant cost savings and reduce carbon footprint by eliminating the need to transport large volumes of high quality aggregates across the country.