Optimizing the production and performance of MgO-based fiber cement using flocculant and recycled fibers

This study evaluates the influence of anionic flocculant dosage on the processing behavior and mechanical performance of fiber cement composites based on Basic Magnesium Sulfate Cement (BMSC), a low-carbon binder derived from magnesium oxide. Recycled textile fibers (RTF) from post-industrial waste were incorporated as reinforcement, replacing conventional fibers commonly used in fiber cement production. Flocculant additions ranging from 0.025% to 0.1% improved drainage efficiency by up to 80% and reduced segregation by approximately 70%, enhancing the uniformity and processing of the composites Flexural strength increased over curing time for all formulations, with the 0.1% flocculant mix reaching a maximum modulus of rupture (MOR) of 9.76 MPa at 28 days. XRD, TGA, and SEM/EDS analyses confirming the formation and stability of the 5-1-7 hydrated phase, which is responsible for mechanical strength development. The flocculant dosage had no detectable impact on the nucleation and crystallization of the 5-1-7 phase, preserving the microstructural integrity of the matrix and the fiber–matrix interface. Physical properties such as water absorption (~22–24%) and apparent density (~1.6 g/cm³) remained stable across all formulations. These results indicate that flocculant incorporation is a viable strategy to optimize processing of MgO-based fiber cement without compromising final performance. The use of recycled textile fibers also contributes to circular economy strategies by reducing the use of lignocellulosic materials traditionally applied in fiber cement production.