Eco materials from CO₂ capture: Compressive strengths of a plasterboard alternative

The utilization of carbon dioxide to produce solid carbonates as construction materials can provide a large-scale sink for CO₂, in terms of long-term storage, while providing a sustainable solution for the industry. In this context, nesquehonite (MgCO₃·3H₂O), that may be precipitated from captured CO₂ and Mg-brines, has been proven as a promising cementitious material. However, the individual and coupled influences of process parameters, at different stages of production, on its mechanical properties is yet to be investigated. The goal of this study is to further the development of a method to synthesise and convert nesquehonite for use as a sustainable, plaster-like cementitious material using a factorial design-based approach. Analysis of variance (ANOVA) has been employed herein to assess the effects of four factors with the aim of enhancing the compressive strength of the final product. These factors included agitation rate, synthesis time, storage time and activation temperature. The products described in this study achieved the highest recorded compressive strengths of NQ-based materials (up to 15.6 MPa), all of which fall within, and exceed, the accepted range for traditional plasterboard manufacture. Observations in the study emphasised the interaction effect between the rate of agitation at synthesis and the activation temperature of the powder, as having the main significant influence. The study clearly indicates the importance of the microstructural of the synthesised nesquehonite, as well as the thermal treatment thereof, on the mechanical properties of the final hardened product.