Assessment of carbonation as a complementary strategy to increase the durability of Magnesium Oxysulfate (MOS)-based fiber cement boards

Abstract

Magnesium oxysulfate (MOS)-based fiber cement boards reinforced with lignocellulosic fibers were manufactured using the Hatschek process and cured for 24, 48, and 72 hours before curing in a CO2-rich atmosphere. The boards were rehydrated before the accelerated carbonation process to evaluate changes in carbonation after water addition to the system. The materials showed property changes after accelerated carbonation, which was responsible for an increase of approximately 15 % in the MOR values of the carbonated boards after 48 hours. In contrast, pre-rehydration of the boards increased the Modulus of Rupture (MOR), Limit of Proportionality (LOP), and Modulus of Elasticity (MOE)values of the carbonated materials and favored the production of cementitious composites with specific energy values close to 4.4 kJ/m2. The quantification of mineralized CO2 showed that the rehydrated and carbonated boards after 48 hours presented the highest SCO2(effective) values, which is related to the densification and consequent decrease in voids in the carbonated materials under these conditions. Accelerated aging showed that the carbonated boards had a lower loss of mechanical properties, demonstrating that accelerated carbonation, in addition to increasing mechanical properties, emerges as an alternative to increasing the long-term durability of MOS-based fiber cement boards.