The durability of structural sandwich elements

Abstract

Structural sandwich elements typically have two thin metal faces and a lightweight core. The core may be polyurethane or polyisocyanurate foamedin situ, or it may be formed from either rigid plastic foam or mineral wool slabstock. It is particularly in the latter case that durability problems may arise which have not been properly addressed by the industry. This paper considers appropriate test regimes for considering the durability of the adhesive bond between the core and the faces. In the case of panels with a core formed of mineral wool lamellae, it also considers possible degradation of the core material. The results of these tests demonstrate that commercially available mineral wools do not have uniform durability. It is necessary to pay particular attention to this factor when choosing core material for structural sandwich panels. Although the research described in this paper was conducted with mineral wool core metarial in mind, it is believed that the procedures are equally applicable to other materials. They are being codified in European recommendations for sandwich panels with additional recommendations for panels with mineral wool core material, published jointly by the European Convention for Constructional Steelwork (ECCS) and the International Council for Building Research Studies and Documentation (CIB).