Thermal and structural performance of precast concrete sandwich panels

Abstract

The energy efficiency of a building predominantly depends on the temperature gradient across the wall. Use of Precast Concrete Sandwich Panels (PCSP) to achieve energy efficiency inside buildings is gaining importance all over the world. PCSPs are used both as precast load bearing wall panels and as precast cladding in buildings due to the high thermal resistance provided by them. PCSPs are generally made up of an insulation layer at its inner core which is sandwiched between two concrete wythes placed on either sides and fixed together using mechanical connectors. The material type of the insulation layer and its thickness predominantly influences the thermal insulation behaviour whereas the concrete wythes take care of the structural stability of the panel. The mechanical connectors provide the required composite action. newlineThe thermal efficiency potential and the increasing popularity for precast concrete in building sector have resulted in considerable innovations in sandwich panel designs in the recent years. Use of high performance thin concrete sections, foamed concrete, fibre reinforced polymer connectors and low conductivity insulation technologies have been developed as a replacement to conventional concrete, steel reinforcement and insulation materials in PCSPs and tested for their thermal and mechanical performance. They provide excellent thermal insulation properties, but a number of research studies have also reported that, new reinforcing materials exhibit low shear strength, brittleness, de-bonding/bond slip and high cost. Also, the structural performance of foamed concrete is questionable due its high porosity. The structural strength of these panels viz. flexural, compressive and shear strengths cannot be compromised for some incremental improvement in thermal properties. newline