Manufacturing and mechanical performance of lightened gypsum reinforced by hemp/epoxy composites

In recent years, the construction industry has increasingly focused on reducing its environmental impact, addressing research efforts towards innovative materials and technological solutions. In this context, gypsum-based materials and natural fibers represent some of the most promising alternatives in terms of sustainability. This paper aims to propose a new gypsum structure reinforced with a composite hemp fabric impregnated with epoxy resin, investigating its manufacturing process and the mechanical properties, specifically in terms of flexural, impact and bearing strength. To achieve lightweight structures, lightened gypsum was also considered in addition to conventional gypsum. Both the lightened gypsum matrix and the hemp/epoxy reinforcement were produced using specific techniques able to obtain lightweight gypsum composites. Beneficial effects in the use of lightened gypsum matrix were found indeed, the reinforced lightweight samples exhibited higher values of flexural strength coupled with a density reduction of about 18%. Additionally, a significant change in post-cracking behavior was observed, with a gradual failure rather than a brittle one. The same trend was observed for the impact, while for bearing strength, the presence of porosity affected negatively the resistance of the composites, prevailing over the benefits of density reduction. Experimental results demonstrated the presence of a good interaction between the hemp fabric and the gypsum matrix, which was further confirmed by the microstructure analysis. The interesting mechanical properties showed by these lightweight gypsum/hemp composites, suggested their possible use for different and unconventional applications of gypsum-based walls and components.