Sustainable reinforcement strategy for green insulation panels: Evaluation of hemp mesh geometry and natural coatings

The composite prefabricated sandwich panels, manufactured with concrete and insulating material, are gaining popularity due to the importance of prefabricated insulation in buildings. The significant difference in mechanical properties between the two elements presents a challenge in achieving good adhesion between the two materials. Since there are some applications where the core insulation materials may also need a mechanical reinforcement; this study proposes a new method that consists of reinforcing the insulating panel with plant-based meshes to enhance mechanical properties and simplify the construction system of the prefabricated panel. To study this reinforcement, a hemp mesh with three different geometries was developed, varying the spacing in the weft direction (15/30/60 mm) and using two coatings (epoxy and colophony). The mesh can be applied externally, adhered to the panel, or internally, embedded within the panel. During the experimental campaign, the reinforcement was validated through two types of tests: pull-out and bending. The results show that bending strength increases by up to a factor of 2.5 in the case of the embedded mesh and 4.0 with the external mesh. The meshes with smaller weft spacing exhibit greater tensile strength in the tensile test but also demonstrate lower adhesion due to reduced penetration of the panel fibers. A weft spacing of 60 mm is found to be the most effective. The results indicate that the reinforcement improvement achieved using epoxy coating does not justify its use over more sustainable alternatives such as colophony. • Developed mechanical reinforcement for low-density bio-based insulation material. • External hemp mesh increases bio-composite flexural strength by factor of 4. • Mesh adhesion to hemp panel depends on coating and weft-direction spacing.