Analysis of Mechanical and Thermal Performance and Environmental Impact of Flax-Fiber-Reinforced Gypsum Boards

Abstract

Gypsum board is a building material known for its various qualities and functional characteristics, including its low density, fire resistance, thermal insulation, moisture regulation, and decorative appeal. However, it is important to consider the environmental aspects, as the production of one ton of gypsum board releases approximately 355 kg of CO2 into the atmosphere. This research aims to reduce the carbon footprint while improving the mechanical and thermal properties of gypsum boards. To achieve this objective, flax fibers of three different lengths (12 mm, 24 mm, and 36 mm) were used to replace gypsum at a certain volume fraction. Incorporating up to 10% flax fiber effectively offsets the carbon footprint of gypsum boards. However, practical constraints related to the processing conditions and mechanical strength limited the addition of flax fiber to levels of 1%, 2%, and 3%. A 3% fiber incorporation gave us a more homogeneous mix with good workability, ensuring good mechanical performance and a 29% reduction in the carbon footprint. This study showed an improvement in flexural strength for flax-fiber-reinforced composites regardless of their length. In particular, the addition of 3% flax fiber (36 mm in length) showed the most significant increase in flexural strength, exceeding 438%. In addition, the mechanical behavior, including toughness, showed improvements over unreinforced gypsum. Flax fibers were found to be effective in bridging microcracks and limiting their propagation. Notably, all reinforced composites showed a decrease in thermal conductivity, resulting in a 47% improvement in thermal insulation with the addition of flax fibers.