Fabrication and structural characterisation of hybrid timber-cardboard sandwich beams

Abstract

This paper develops a novel class of timber-cardboard sandwich (TCS) panels, consisting of low-cost timber facings and a block-laminated corrugated cardboard core. Experimental and analytical studies are conducted to characterise the flexural performance of TCS beams made from recycled or waste materials. TCS beams made from scrap cardboard cores have the exceptional characteristic of being made mostly from waste, up to 91% by volume or 76% by weight, and are demonstrated to have equivalent performance to beams made with recycled cores. TCS beam flexural behaviour is found to be primarily governed by timber face sheets, with very strong composite action and no observed core shear or debonding failure. The strength, stiffness, and dominant failure mode of TCS beams are thus shown to be accurately predicted using composite sandwich beam theory and cross-sectional analysis. TCS beam bending strength is also found to be significantly higher than conventional foam-core structurally-insulated panels with comparable densities, making them highly viable as a bio-based structural alternative. These research findings enhance the capacity and confidence by which cardboard can be used as a construction feedstock, supporting societal progression toward a greener and more circular economy.