Precast lightweight foamed concrete sandwich panel (PLFP) tested under axial load: preliminary results

Abstract

A study is carried out to develop a Precast Lightweight Foamed Concrete Sandwich Panel, PLFP, as a new and affordable building system. Experimental investigation to study the behaviour of the panel under axial load is undertaken. The panel consists of two lightweight foamed concrete wythes and a polystyrene insulation layer in between the wythes. The concrete panels are reinforced with 9mm diameter high tensile steel bars. The rebars are tied to each other through the insulation layer by shear connectors which are made of 6mm mild steel bars bent to 45º angle. Total number of four specimens was tested with one specimen; PA1 was cast without capping at both ends. It was used as a pilot test. The other three specimens are capped with normal concrete at both ends to avoid end crushing during axial loading. Axial load test was conducted and the results are presented here, which include the ultimate load capacity, crack pattern and failure mode, strain distribution and load-deflection curve of the panels. The experimental ultimate strength achieved recorded lesser percentage difference with the formulae by Pillai and Parthasarathy when compared to formulae in BS8110. It is also observed that the strength of the panels are affected by the compressive strength of the foamed concrete forming the wythes, the presence of concrete capping at panel’s ends and the slenderness ratio, H/t. Specimens with capping at both ends recorded higher ultimate loads with no premature crushing. Failure of panels with slenderness ratio, H/t < 18 were by premature buckling near the supports whereas for panels with higher H/t ratio, slight bending was observed in the middle zone. The results also indicate that a certain degree of compositeness is achieved between the wythes.