Utilization of quarry by-products for reduction of expansion due to alkali-aggregate reaction

The replacement of normal fine aggregate with high fines limestone screenings is a technique to reduce waste from crushed stone operations, while potentially improving the durability and performance of concrete. The main objective of this research is to evaluate varying percentages of high fines limestone screenings as a partial weight replacement of reactive fine aggregate (similar to limestone sweetening) in mortars to assess reductions in the expansion due to alkali-aggregate reaction (ASTM C 227, ASTM C 1260, and modified ASTM C 1105). Fresh and hardened properties have been evaluated to assess the effects of limestone screenings on performance criteria. Environmental scanning electron microscopy (ESEM) was performed to visually observe and confirm alkali-aggregate reaction products and associated damage. From the physical testing and microstructural analysis, it was found that 50% or more of limestone screenings significantly reduce expansions due to alkali-aggregate reaction, attributed to the preference for monocarbonate formation in the presence of limestone and/or reactive silica dilution. Replacements less than 50% did not significantly reduce expansion.