Effects of rapid electrical curing and internal curing with cellulose microfibers on alkali-activated fly ash mortar

Abstract

This study investigates an electrical curing method for the appropriate pre-casting application of alkali-activated fly ash (AAFA) composites, which offer a low-carbon alternative to traditional cement. Cellulose microfibers (CMFs) were incorporated into AAFA mortar to induce internal curing and prevent self-desiccation. The thermal conductivity of hardened AAFA mortar was measured at relatively low 0.461 W/mK. This emphasizes the necessity of an electrical curing method for the proper curing of AAFA mortar. Temperature change and its distribution on the AAFA surface was monitored during 24-hour electrical curing, revealing that electrical curing sufficiently cured AAFA mortar with a spacing of over 10-cm between the electrically conductive cementitious composite (ECCC) elements. Compressive strength tests showed that AAFA mortars with CMFs had greater strength than plain AAFA specimens. Microstructural analyses, including XRD, TG/DTG, and MIP, demonstrated that CMFs promote the formation of C-S-H, while reducing the amounts of calcium hydroxide and calcite, formed from false setting. Furthermore, CMFs effectively reduced pore sizes in the 300-1000 nm range, leading to decreased average pore diameter and enhanced material durability.