City University of New York. University Transportation Research Center

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This report summarizes the findings of an experimental investigation into shrinkage, and the mitigation thereof, in alkali-activated

fly ash and slag binders and concrete. The early-age (chemical and autogenous) and later-age (drying and

carbonation) shrinkage of sodium silicate-activated fly ash and slag binders was evaluated in accordance with relevant

specifications. The influence of activator concentration and water content on the resulting shrinkage was investigated. The

shrinkage behavior of alkali-activated binders and concrete was compared to that of ordinary portland cement. Finally, the

effectiveness of several common shrinkage-mitigation techniques on the early-age and later-age shrinkage of alkali-activated

binders was evaluated.

Overall, this study demonstrates that, while shrinkage and associated cracking are problematic in many alkali-activated

concrete mixtures, there are several promising methods which can reduce the magnitude of autogenous and drying shrinkage.

US Transportation Collection

49997-24-25