Influence of different curing regimes and accelerated carbonation on the physical, mechanical, and aging performances of fiber cement

Abstract

The curing process in fiber cement is essential to improving the characteristics of the fiber-matrix interface, physic-mechanical performance, and durability. This work studied the effect of different curing regimes and accelerated carbonation on fiber cement to optimize these materials' production stages and physic-mechanical performance. The fiber cement flat sheets were produced with 10% bleached eucalyptus pulp by slurry-dewatering method to reproduce the commercial Hatschek process. Carbonated and non-carbonated samples were assessed at different regimes and curing ages to provide a comparative parameter. Thermal curing at 60 °C (7 days) and wet curing (28 days) was carried out after carbonation as supplementary curing. The accelerated carbonation was performed in a climatic chamber at 60 °C, 90% RH, and 20% CO2 concentration. Accelerated aging trials were also conducted for durability evaluation. X-ray diffraction, TGA, and scanning electron microscopy analyses determined the mineralogical composition, chemical components, and fiber cement microstructure. Mechanical results presented an average increase of 33% in resistance of carbonated samples compared to non-carbonated fiber cement. Additional curing increased the materials' hydration potential and demonstrated an 11% increase in calcium carbonate amounts. However, there was no statistically significant difference in fiber cement’ physic-mechanical performance with additional curing. The carbonated samples without supplementary curing presented a fiber-matrix interface like that observed in other curing regimes, even after being subjected to a shorter curing time (3 days) and accelerated aging cycles. The accelerated carbonation process enables the materials’ production at reduced ages, achieving physic-mechanical performance and durability like materials produced at more advanced ages with conventional curing regimes.