Thermal performance of super-insulated precast concrete structural sandwich panels

Precast concrete sandwich panel (PCSP) is introduced to improve the thermal performance of solid concrete panels by sandwiching an insulation layer between the concrete layers or wythes. The two concrete layers are connected through the insulation using C-shape shear connectors. The shear connector makes these concrete wythes to act as one panel and allow it to be a load-bearing sandwich panel to carry lateral force. In PCSP, material and arrangement of connectors influence both thermal and structural efficiencies of the system. The existing sandwich panels employ direct shear connection method (truss, bent-up bars, pin etc) which reduces its thermal resistance. Attempts to use three-layer PCSP led to an un-economical section and increased production time while alternative materials approach such as the use of fibre reinforced polymer (FRP) for shear connection leads to a reduction in structural performance. Hence, this paper presents a renewed approach to the development of two layers PCSP using thermal path method. In this method, the concrete layers are produced in split units and assembled together with the insulation layers. The improvement of thermal resistance is measured with three staggered spacing of shear connectors at 200 mm, 300 mm and 400 mm in the column stud along the height of sandwich panels designated P2, P3 and P4, respectively, while, the control spacemen is P0. Heat transfer was experimentally measured using Hot Box Test (HB) method and the results were verified using 3D component of COMSOL Multiphysics Software (CM). Thermal resistance, transmittance, and conductivity of the assembled panels obtained were 0.7-2.35 m2K/W, 0.06-0.21 W/mK and 0.43-1.43 W/m2K, respectively. It can be concluded that the most staggered panel (400 mm) achieved the highest thermal resistance compared to others. This proofed that better thermal resistant building can be achieved with conventional steel and concrete materials using thermal path approach. Hopefully, this super-insulated precast concrete structural sandwich panel (SIPCSSP) will provide a better thermal resistance load bearing panel to the industry in the near future towards green and sustainable buildings.