Development of thin precast concrete sandwich panels: Challenges and outcomes

Abstract

The development of thin precast concrete sandwich panels presents many structural, thermal and practical challenges. This study outlines the design, testing and production of novel panels constructed of two layers of high strength, fibre-reinforced concrete that sandwich a layer of high performance insulation. The layers are connected with fibre reinforced polymer grid connectors in an effort to achieve composite action. Thin precast concrete sandwich panels offer weight and material savings over standard reinforced concrete panels, that enable manufacturing, transport and onsite efficiencies, as well as reduced embodied energy. Much current research, focused on reduced concrete section thickness, prioritise the use of textile reinforced concrete which requires specialist equipment and manufacturing methods. This work instead presents a solution that is suitable for production in standard precast facilities. The design development and testing of different design iterations is outlined. Ten samples of 3 m high panels are tested structurally using flexural tests. The panels are tested thermally using experimental techniques and finite element analysis. A case study is presented on a demonstration building. It achieved bending moment capacities in excess of the design wind load requirements, a measured U-value less than 0.18 W∙m−2∙K−1 and post cracking residual strength ensuring a ductile failure. Hence, the final panel design is deemed to achieve both structural and thermal requirements of a high performing cladding element. The panel was developed at scale in a precast facility for practical implementation on a building in-use.