Structural sandwich composites out of wood foam core and textile reinforced concrete sheets for versatile and sustainable use in the building industry

Sandwich components can combine very stiff mechanical properties with very low weight due to shear resistant core materials and load bearing cover sheets and are well established in the building industry in the façade application and a number of indoor usages are known. Such sandwich cores are mainly made from polymer foams, such as PUR or XPS, cover sheets are made from metal, polymer sheets or fiber reinforced concrete. In this work wood foam (100% fibers without a synthetical binder) is used as a sustainable alternative to polymer-based core materials in façade elements with fiber-reinforced concrete. Wood foams made from pine and beech were manufactured in a density range from 50 to 250 kg/m³ and investigated on strength, insulation properties and fire retarding. It was found, that wood foams in comparison to widely used polymer foams have comparable properties in thermal insulation and also strength, wood foam from beech achieved a disproportionately higher noise reduction. Used in a sandwich, the wood foam core can be adhesively bonded with established construction adhesive or adhesion can be provided by the core or sheet element itself by casting or grouting concrete out of the liquid phase direct on wood foam. Therefore a number of material combinations and processes are possible.