Experimental assessment of shear connectors for sandwich hemp insulation panels with FRCM and 3D printed wythes

This study investigates a novel enclosure solution comprising an inner FRCM (Fabric Reinforced Cementitious Matrix) structural layer and an outer 3D-printed mortar layer, connected to a hemp-based insulation panel via flexible connectors. The sandwich solution requires a proper shear transmission between layers. Two surface adaptations of the insulation panel—bonded particles and bonded mesh—and two types of punctual connectors—shredded yarn and closed staples—are analysed for their performance under direct shear, flexural, and pull-out (adherence) tests. Results show that connectors do not improve flexural response, but closed staples effectively resist shear when mortar penetration is manually ensured. Among surface adaptations, bonding a hemp mesh enhances strength across all tested efforts. Consequently, the combination of no connectors and a bonded hemp mesh emerges as the most viable solution for further research. A global mechanical assessment confirms that this connection method supports handling and installation of panels up to 900 mm in length • Bonding a mesh on the insulation layer improves the connection with mortar. • Manually applied mortar assures connector interaction. • Closed staple connectors improve shear and adherence performance. • 3D printed mortar is not penetrating mechanical shear connectors.