Using Accelerated Test Methods to Specify Admixtures to Mitigate Alkali-Silica Reactivity

Abstract

Abstract The development of accelerated tests for alkali-silica reactivity (ASR) included the investigation of a wide range of aggregates and cements that gave results indicating the potential reactivity of these combinations. The development procedure did not provide for comparison of specific aggregates and cements in areas where ASR is known to be of concern. Through the development of a matrix comparing available materials and their reactions, specifications for concrete proportions may be developed to further alleviate the effects of ASR in a specific area. Tests conducted, using New Mexico aggregates and available admixtures in conjunction with AASHTO Test Method T 303, indicated that fly ash and fly ash/lithium admixtures resulted in significant reduction in expansion of mortar bars. The matrix for this research involved five fly ash sources, five aggregate sources, one local cement, and a lithium nitrate solution. Subsequent to this research, the New Mexico State Highway and Transportation Department has implemented the findings into their specifications for infrastructure concrete.