Development and testing of a sandwich panel with UHPC and PCM concrete layers

Precast concrete sandwich panels provide a thermally efficient alternative to conventional brick and mortar construction and improve the energy efficiency of existing buildings. This project comprised the design and testing of a sample re-cladding panel composed of a phase change material (PCM) in the concrete inner wythe (for thermal efficiency) and a thin ultra-high performance concrete (UHPC) outer wythe, joined compositely using a C-grid shear connector. Six different concrete mixes were prepared and structurally tested in compression and flexure. A concrete sandwich panel was cast using two of the best performing mixes and subsequently tested in three-point bending to investigate its flexural performance. The strongest PCM and UHPC concretes had average compressive and flexural strengths of 25MPa and 5.1MPa, and 121MPa and 9.2MPa respectively. The 900mm span panel tested in flexure reached its serviceability limit at 10kN, with ultimate peak load occurring at 97kN. Post-peak behaviour illustrated the role of the shear connector in allowing composite action to occur.