Flexural characteristics of bio-based sandwich beams made of paper honeycomb cores and flax FRP skins

Sandwich structures have been used for building applications as building envelope and cladding systems. The sandwich structures used today are typically made of conventional Fiber Reinforced Polymer (FRP) made of synthetic fibers such as glass and carbon, and synthetic foam core. With the increasing of environmental consciousness, it is important to develop sustainable building materials to replace conventional building materials. The use of bio-based materials for construction is a good way to improve the sustainability of buildings. However, bio-based sandwich structure has not been widely used today. Therefore, it is essential to investigate and understand the characteristics of structures made with bio-based materials. In this study, a total of 18 large-scale bio-based sandwich beams made of flax FRP skins and two types of paper honeycomb core were studied. The parameters of the tests were skin thickness (1,2 and 3 layers of flax FRP) and core types (namely, hollow and foam-filled). Each specimen was 1200 mm long, 100 mm wide and approximately 80 mm thick and was tested by three- point bending. The failure modes were observed, and the test data were collected and processed. The test results were shown by load-deflection diagrams, and moment-curvature diagrams. Overall, the bio-based sandwich structures have potential to be used for building applications with much less environmental footprints in comparison with other synthetic counterparts.