Influence of natural fibers on hydration and carbonation of reactive magnesium oxide cement (RMC)

This study offers insights into the influence of cellulose fibers at 0, 0.25, and 0.5 vol% on the hydration and carbonation of reactive magnesium oxide cement (RMC). The cumulative heat increased with the fiber content, attributed to the nucleation and possibly internal curing effects of the fibers. The reinforcing action provided by the fibers also improved the mechanical performance of the air-cured samples, yet the compressive strength under 20% CO2 and 80% RH was maximized at 0.25 vol%. At 0.5 vol%, the contents of brucite and carbonates were reduced due to confinement and crack control, which restricted the growth of brucite and CO2 diffusion. The carbonation phase was mainly poorly crystalline or amorphous, marked by a fused structure and with a thermal decomposition peak at approximately 405 °C. The cellulose fibers with a porous cell wall and cavity provided a pathway for enhanced CO2 diffusion, resulting in concentrated carbonates at the fiber-matrix interface.