Review of precast concrete sandwich panels and their innovations

Abstract Precast concrete cladding is experiencing a resurgence in popularity as a means of building cladding. Precast concrete sandwich panels are a specific type of precast cladding, characterised by high thermal resistance provided by a layer of insulation which is sandwiched between two concrete wythes and fixed together with mechanical connectors. Hence, they have the potential to offer a thermally efficient cladding solution for new buildings and as replacement cladding in the case of renovation. Due to this thermal efficiency potential, and the resurgent popularity of precast concrete generally, considerable innovation in sandwich panel design has occurred in recent years. New high-performance concrete, with novel means of reinforcement, have enabled lighter and thinner concrete wythes. Numerous new fibre reinforced polymer connectors have been developed and tested that facilitate shear load transfer across the layers while also minimising localised heat loss. State-of-the-art low-conductivity insulation technologies allow for remarkably low U-values for thin wall build-ups. All these innovations are increasing the applicability of sandwich panels for a wider range of building typologies and are augmenting the inherent benefits of precast cladding. A review of precast sandwich panels is therefore timely to evaluate the body of research undertaken and analyse proposed design-solutions and test-results to identify future research focuses. This review determines particular advancements in the development of high strength concretes with no steel but that achieve high flexural strengths. It reviews the considerable number of studies focused on the structural performance of sandwich panels but highlights a need for further thermal validation of novel sandwich panel designs and further testing of different connector types.