This article analyzes the effect of the rehydration method on the physical–mechanical properties of accelerated carbonation-cured magnesium-based fiber cement boards. The rehydration process of the boards was analyzed in conjunction with the analysis of the pre-curing time before accelerated carbonation (24, 48, and 72 h before carbonation), resulting in eight different curing parameters used in this investigation. The physical–mechanical performance and microstructural characteristics of magnesium oxysulfate boards before and after carbonation were investigated by water absorption, apparent porosity, and bulk density using the four-point bending test, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. According to the results, the accelerated carbonation process improved the mechanical properties of the boards. The samples that carbonated after 48 h showed a higher modulus of rupture. The rehydration process of the composites before carbonation led to enhancements in the pre-cured boards for 48 and 72 h, demonstrating that carbonation occurred more effectively after water rehydration. The mechanical improvements were associated with the formation of hydration products, which preferentially formed in the pores and voids of the fiber cement matrix. These carbonation products altered the physical properties of the composites, increasing the density of the boards and reducing the void volume. The decomposition of the formed carbonates was confirmed by thermogravimetric analysis, which indicated that the rehydration process favored the carbonation of the composites.

This study investigated the effects of substituting magnesium oxide (MgO) with dolomitic limestone (DL) on the mechanical and physical properties of magnesium oxysulfate (MOS) cement. Additionally, the hydration formation phases and the influence of the molar ratio on the MOS cement’s performance were examined. The corresponding action mechanisms were identified and explored by compressive strength tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), isothermal calorimetry, and a thermogravimetric analysis (TGA). The results showed that replacing MgO with DL decreased the reaction speed and heat release rate generated in the hydration process of the MOS cement. This substitution also reduced the quantity of non-hydrated MgO particles and delayed the formation of Mg(OH)₂. The diminished formation of Mg(OH)₂ contributed to an increase in the apparent porosity of pastes containing DL, thus alleviating internal stresses induced by Mg(OH)₂ formation and enhancing their mechanical strength after 28 days of curing. Conversely, the increased porosity improved the CO₂ diffusion within the structure, promoting the formation of magnesium carbonates (MgCO₃). Through the characterization of the cement matrix (XRD and TGA), it was possible to identify phases, such as the brucite, periclase, and 318 phases. The obtained results revealed the potential of incorporating mineral fillers like limestone as a promising approach to producing MOS cement with a reduced environmental impact and better properties at higher curing ages.

Basic magnesium sulfate cement (BMSC) is a non-conventional binder with advantages such as fire resistance, lightweight properties, and low alkalinity, widely used in lightweight panels. However, the effects of cellulosic fiber incorporation on the hydration mechanisms and mechanical performance of BMSC remains insufficiently explored. This study evaluates the effects of incorporating different dosages of bleached eucalyptus fibers (EB) on the physical, mechanical, and microstructural properties of BMSC composites. Additionally, it examines their influence on hydration reactions and phase formation to determine optimal compositions for construction applications. The composites were analyzed using mechanical tests, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and DIC. Results indicate that the 5-1-7 phase enhances mechanical strength through a space-filling effect, while fiber incorporation increases porosity and alters phase distribution. Higher fiber contents led to increased porosity and a reduction in compressive strength, whereas flexural strength and energy absorption were improved due to fiber-bridging effects. These findings highlight the potential of optimizing fiber dosage to balance strength and toughness in BMSC composites for construction applications.

The natural variability and moisture sensitivity of bamboo limit its widespread use in construction applications. To address these challenges, densification and delignification processes have emerged as promising modification techniques. Densification and delignification processes can lead to significant improvements in the physical, mechanical, and chemical properties of solid wood. In this study, a two-step process of delignification and densification was carried out on Dendrocalamus asper bamboo specimens. The objective was to assess whether the optimized parameters of densification for natural bamboo on an open pressing system can be transferred for delignified bamboo. Delignification was achieved using an alkali solution (NaOH and Na₂SO₃) with two different temperature settings (25 °C or 100 °C). The pre-treated samples were dried in one of the two different conditions, either at 100 °C for 24 h or 25 °C for 30 days, resulting in four different groups with an average moisture content ranging from 7 to 10%. The samples were densified to 50% of their original thickness through an open thermo-mechanical press system at 160 °C with a compression rate of 6.7 mm/min and compared to densified bamboo without delignification (reference). The compression stress required to achieve a 50% degree of densification was evaluated, with untreated samples exhibiting an average value close to 17 MPa. Following treatment, the compression stress ranged from 7 to 13.4 MPa, indicating that the exposure to a high pH solution facilitates the densification process. However, a reduction in flexural properties (MOR, LOP, and MOE) was observed on the alkali-treated samples after a three-point bending test. Physical properties (water absorption and thickness swelling) were not altered after delignification. These findings demonstrate that the direct application of a densification process optimized for natural bamboo is not fully effective for chemically modified bamboo, highlighting the need for adjustments. Delignified bamboo showed an increase in free space after chemical treatment, which should be further densified under higher degrees.

Fiber-reinforced cementitious composites have become increasingly important in the development of durable and sustainable construction materials, particularly following the replacement of asbestos-based reinforcements. However, the long-term performance of these composites is strongly influenced by the characteristics of the fiber–matrix interface, where moisture transport, interfacial degradation, and stress transfer mechanisms govern durability and mechanical behavior. Consequently, considerable efforts have been devoted to developing surface engineering strategies capable of improving fiber–matrix compatibility and enhancing composite performance. This review examines recent advances in surface modification and interfacial engineering approaches applied to fiber-reinforced cementitious composites. The discussion covers fiber–matrix bonding mechanisms and the main modification strategies, including alkali treatments, hornification, silane coupling agents, polymeric and hydrophobic coatings, nanomaterial-assisted modifications, and carbonation-induced surface engineering. The effects of these approaches on interfacial properties, durability, dimensional stability, and mechanical performance are critically assessed. The literature indicates that treatments combining surface chemistry modification, moisture control, and mineral-based densification provide more consistent improvements in durability than single-mechanism approaches. Future developments are expected to focus on scalable treatment methods, low-carbon cementitious systems, and advanced materials design strategies, enabling the development of next-generation fiber cement composites with enhanced durability, sustainability, and long-term performance.