Assessment of the physical-mechanical performance of magnesium-based fiber cement submitted to accelerated carbonation

Abstract

In the search for unconventional binders that reduce energy consumption in production, magnesium oxysulfate (MOS) cement is an alternative. Besides that, the carbon dioxide (CO2) has been used to curing some products of MOS cement, for instance, magnesium fiber cement because this method improves their performance. The aim of this paper is to evaluate the effect of pre-curing before accelerated carbonation on the physical-mechanical changes of magnesium fiber cement boards. These boards were produced by the Hatschek process simulation and submitted a pre-curing of 24h, 48h and 72h after production. The correlation between microstructural changes and the physical-mechanical properties was observed by water absorption, apparent porosity, and apparent density, four-point bending test, X-ray diffraction and SEM analyses. The results demonstrated that pre-curing influenced the physical-mechanical properties of the produced boards. The carbonated materials after 72 hours showed a decrease in mechanical performance, which was attributed to the carbonation reactions between CO2 and the hydration products responsible for the enhance of mechanical strength of the cementitious materials.