Effect of precuring time on the strength, microstructure, and energy consumption of direct electric curing concrete

Abstract

The study assesses the role of precuring duration in facilitating the rapid curing of concrete and its associated impacts on current, resistance, and temperature variations during direct electric curing (DEC) of concrete. Additionally, the research examines the effects of precuring duration on aspects such as concrete strength development, pore structure, hydration product morphology, and the interfacial transition zone. For a comprehensive analysis, it introduced the "unit-strength energy–time product" as a measure to compare the relative benefits and drawbacks of DEC and steam curing concerning concrete productivity and environmental implications. the findings reveal that the variations in current, resistance, and temperature during DEC are affected by the precuring time duration, with both current and temperature decreasing with an increase in precuring time. A precuring duration of 90 min under DEC yields an early high strength. At this point, the 1 d compressive strength of the concrete specimen is 51.5 MPa, representing 90.51 % of the 28 d strength, without any significant reduction in the late strength. DEC also mitigates the pore-coarsening effect induced by steam curing, thereby reducing the specimen's porosity and enhancing the performance of the interfacial transition zone. The precuring time and energy required for DEC are significantly lower compared to steam curing. The optimal DEC regime, consuming a mere 450 min, contrasts with the lengthy 780 min process required for steam curing. By considering time and energy consumption, the unit-strength energy–time product of DEC ranges between 22.01% and 27.86 % (at age 1 d) and 17.93%–23.45 % (at age 28 d) of that of steam curing. In summary, the research provides evidence that an appropriately devised DEC regime can augment production and energy efficiency, possibly instigating a technological transformation in contemporary construction practices.