Performance Assessment of Gypsum-Based Composites with Coconut Fibers: Durability, Circularity, and Environmental Impact Assessment

Gypsum-based composites are widely used in construction for their rapid setting and fire resistance; however, their low mechanical strength and limited durability in humid conditions restrict their use in highly humid indoor environments. In this study, gypsum-based composites were developed with a partial volumetric replacement of up to 17.5% using pre-consumer coconut fiber waste (an agro-industrial by-product) as a reinforcing material. The experimental program was structured in four stages. First, the hygrothermal behavior of commercial gypsum composites containing coconut fiber was assessed through accelerated aging tests, including water-oven cycles and humid chamber-air cycles. Second, the Building Circularity Index (BCI) was estimated at life cycle stage C3 (waste treatment), considering the separation and recovery of gypsum and coconut fibers at the end of life (EoL) of a panel made from gypsum and coconut fibers. Third, three series of composites incorporating pre-consumer recycled gypsum (an industrial by-product) as a binder and coconut fiber, with substitutions of 5%, 10%, and 15%, were produced and mechanically characterized. Finally, a comparative Life Cycle Assessment (LCA) was carried out on two laboratory-scale panels: a gypsum panel and a recycled gypsum panel, both reinforced with coconut fibers. The results show that coconut fibers act as a hygrothermal stabilizer within the gypsum matrix. Following accelerated aging cycles, all formulations maintained flexural strengths greater than 1 MPa and compressive strengths greater than 2 MPa, despite maximum losses of 34.7% and 41.8%, respectively. Meanwhile, the series containing recycled gypsum showed a reduction in compressive strength of up to 74.4%, with only the mix containing 5% fiber meeting the minimum regulatory requirements. The circularity analysis showed a recovery potential of 50.34% for gypsum and 44.99% for coconut fiber at EoL, with a maximum BCI of 13.70%. Finally, the LCA confirmed a reduction in Global Warming Potential of up to 80% in panels made with recycled gypsum. In conclusion, this research suggests the technical potential of commercial gypsum reinforced with coconut fiber, whereas for recycled gypsum matrices, only the 5% fiber formulation is identified as technically viable lightweight building components.