Composite behaviour of wide sandwich panels with thin high performance recycled aggregate concrete wythes with fibre reinforced polymer shear connectors

ABSTRACT The traditional means of using precast concrete sandwich panels are restrictive in terms of applications, where thick wythes result in heavy panels which are often unsuitable in retrofitting domestic and commercial buildings. As concrete sandwich panel technology has evolved to make it more widely accessible, recent research work has demonstrated that it is possible to achieve thermally efficient partial composite action within a thin wythe panel provided non-conductive shear connectors are used. This paper examines high performance recycled aggregate concrete in heavily insulated non-load-bearing panels for retrofitting domestic and commercial buildings. A series of concrete mixes were tested to develop one which would be more sustainable than the widely accepted standard mixes for wythes. Different 220 mm thick concrete sandwich panels were tested consisting of 20 mm thick fibre-reinforced recycled aggregate concrete wythes and a 180 mm layer of XPS insulation. Unconnected and shear connected panels were tested in flexure in a displacement control test. The effects of composite action and post-cracking toughness were examined and it was concluded that a shear connected panel comprising sustainable thin recycled aggregate concrete wythes enclosing a thick layer of insulation is a feasible product to use for light high-performance sandwich panels.