Assessment of Ground Soda-Lime Glass Pozzolan When Used with Non- or Marginally- Alkali Silica Reactive Aggregates

Abstract

Industrial byproducts such as fly ash have been used as supplementary cementitiousmaterials (SCMs) for many years to improve concrete properties and reduce demand for portland cement, thereby reducing CO2 emissions. Due to recent closures of coal power plants, the supply of fly ash has declined significantly, leading to research on alternative SCMs. Ground soda lime glass (glass pozzolan) has shown promise in this application due to its widespread availability and favorable chemical composition. However, due to the high alkali content in the glass, concerns have been raised over the mitigation potential and even possible exacerbation of alkali silica reaction (ASR) in concrete mixtures. Previous research indicates concrete containing ground glass pozzolan undergoes unacceptably high expansion when combined with highly reactive aggregate. This research investigates the ASR mitigation potential of ground glass pozzolan in concrete mixtures containing three mildly reactive fine aggregates, which are widely available throughout the United States. A commercially available ground soda lime glass pozzolan was used at 10, 20, and 30% portland cement replacement levels, and compared to fly ash and inert fillers at the same levels. Expansion due to ASR was measured using ASTM C1567, ASTM C1260, and AASHTO T380 while compressive strength was measured using ASTM C192 and ASTM C109. Compressive strength was monitored as previous research indicates that increased pozzolan dosages result in lower early compressive strengths. Results from this study indicate concrete containing mildly reactive aggregates combined with soda lime glass pozzolan performs acceptably in most cases while concrete containing highly reactive aggregates combined with soda lime glass pozzolan will not perform acceptably. Ternary mixtures including soda lime glass pozzolan and fly ash were found to have improved expansion performance while still suffering from relatively low early compressive strength. Expansion and compressive strength data from this study will help inform engineers regarding the use of soda lime glass pozzolan in concrete mixtures containing mildly reactive aggregates.