Flexural Performance of Low-Cost Lightweight Low-Bearing Sandwich Panels with Minimal Shear Reinforcement

• Lightweight thermal insulated plates for jack-arch roofing applications were tested. • Four-point flexural tests were conducted on 18 SCC 10 mm-facings sandwich plates. • Six wire reinforcement configurations were evaluated at early and mature ages. • Load capacity, stiffness, ductility, toughness, and composite action were analysed. • Test showed that all specimens exhibited adequate composite action until cracking. • Plates with 2.5 mm wires spaced at 60×60 mm recorded optimum structural efficiency. Concrete sandwich panels are typically used when thermal insulation is a key parameter for walls and floors. Extensive studies have explored the structural performance of sandwich panels, whereas few studies have focused on low-load-capacity roofing panels. The experimental work in this study aimed to evaluate the structural efficiency of lightweight, low-cost, and low-capacity cementitious sandwich panels. Each panel weighs approximately 20 kg, making it suitable for quick and cost-effective jack-arch roofing systems in housing and industrial applications. Eighteen panels with 10 mm top and bottom self-compacting concrete facing layers insulated by a 50 mm insulation core, were tested under four-point bending. Six steel wire mesh configurations with different diameters and spacings were examined to select an optimum cost-effective tensile reinforcement mesh. The six meshes defined the six groups G1, G2, G3, G4, G5, and G6. From each group, three identical panels were tested at early and mature ages of 3, 7, and 28 days. The evaluation of the panels considered multiple structural response parameters, including cracking and ultimate loads, cracking patterns, stiffness, ductility, toughness, and composite action. The results showed that most of the tested panels retained acceptable load capacities and failed in ductile flexure at early and mature ages. G5 panels with 2.5 mm diameter wires spaced at 60×60 mm exhibited the optimum structural response at early and mature ages and recorded the highest normalized structural efficiency among the six groups.