Assessment of the fracture behavior of commercial quasi-brittle gypsum boards with and without reinforced paper fibers used in timber modules

One adopted solution for the building sector to reduce greenhouse gas emissions and fulfill the environmental requirements imposed on modern construction is the use of prefabricated timber modulus. However, gypsum plasterboards mounted in the sheathing walls of such modules are susceptible to fracture near the door openings during the on-site installation (lifting) and by horizontal loads. In this regard, fracture properties of the plasterboards are essential to be measured and integrated in structural models of the modules to predict the crack initiation and propagation toward better structural design. Here, two commercial plasterboards typically used in the timber modules, an ordinary gypsum board and a fiber gypsum board with reinforced recycled paper fibers, were evaluated under standard fracture tests for estimating the fracture properties. The fracture toughness of the fiber gypsum board (= 800 J/m²) was twice as high as of the ordinary gypsum board (= 400 J/m²) as well as the tensile strength evaluated at the peak forces and the traction-separation laws during the crack growth. The superior mechanical properties for the fiber gypsum board are attributed to their higher density and fiber reinforcement, and its resistance to cracking to the fiber bridging during the crack growth. Post-mortem micrographs revealed fibers almost intact with gypsum fine particles on the surfaces due to the fiber pull-out mechanism. The fracture process of the ordinary gypsum board was much affected by its paper surfacing, but a tortuous crack path was found in the gypsum core due to the significant amount of porous.