Coupled effect of expansive agent and curing on mechanical and shrinkage properties of fiber-reinforced Eco-Crete

Abstract

This study evaluates the effectiveness of various shrinkage mitigating strategies on the properties of economical and ecological concrete (referred to here as Eco-Crete) made with a low binder content and 55% substitution of cement with fly ash and slag cement. Shrinkage mitigating strategies were included the use of Type G expansive agent (EA), saturated lightweight sand (LWS) for internal curing, and 0.5% micro–macro steel fibers. The coupled effect of these materials along with external moist curing (MC) of 1 and 14 days on mechanical and shrinkage properties was investigated. Eight plain and eight fiber-reinforced Eco-Crete mixtures were tested for compressive strength, flexural strength, drying shrinkage, and restrained expansion. Induced stress resulting from the restrained expansion of the Eco-Crete mixtures was determined, and a multiple regression model was developed to estimate the internally induced stress. MC, EA content, fiber volume, and coupled effect of EA-fiber were found to be significant in enhancing the induced stress. The Eco-Crete mixtures including 10% EA and 14 days of MC exhibited the maximum initial expansion and minimum shrinkage in both shrinkage and restrained expansion length change experiments. The coupled effect of EA and fiber reduced 112-d shrinkage and restrained expansion length change by up to 26% and 54%, respectively, compared to the system made with EA, LWS, and fiber. The highest induced stress and flexural strength of 25 kPa and 6.2 MPa, respectively, were obtained by the mixture made with 10% EA and 0.5% fiber.