Water migration mechanism during internal curing of cement composites with cellulose microfibers

Abstract

This study aimed to investigate the internal curing mechanism of cement composites containing cellulose microfibers (CMFs) derived from kenaf stalk bast. The primary test variable was the CMF content, which controlled the amount of water absorbed by the CMFs, thereby facilitating internal curing. The evolution of proton signals from time-domain nuclear magnetic resonance (NMR) was analyzed for the solid phases and various mobile water components during the curing process. The NMR results showed strong correlation with the thermal decomposition and degree of hydration, as determined by thermogravimetry and quantitative X-ray diffraction, respectively. The higher CMF content led to a delayed onset of hydration at early age. Moreover, the internal curing process was supported by the delay in the detection time of the solid-phase signal and an increase in signal intensities of the interlayer water and solid components, indicating the formation of hydrated phases. These insights clarify the significant role of CMFs in enhancing internal curing effects in cement composites.