A Bio-Based Render for Insulating Agglomerated Cork Panels

Natural and bio-based thermal insulation materials play an important role in the lifecycle impact of buildings due to their influence on the amount of energy used in indoor temperature control and the environmental impact of building debris. Among bio-based materials, cork is widespread in the Mediterranean region and is one of the bio-based materials that is most frequently used as thermal insulation for buildings. A particular problem is the protection of the cork-agglomerated panels from external stress and adverse weather conditions; in fact, cork granulates are soft and, consequently, cork panels could be damaged by being hit or by excessive sun radiation. In this study, an innovative external coat for cork-agglomerated panels made of a blending composite of beeswax and rosin (colophony) is proposed. The performance of this composite, using different amounts of elements, was analysed to discover which mix led to the best performance. The mix of 50% beeswax and 50% rosin exhibited the best performance out of all the mixes. This blend demonstrated the best elongation and the lowest fracture density, characteristics that determine the durability of the coating. A performance comparison was carried out between cork panel samples coated with lime render and beeswax–rosin coating. The coating of beeswax and resin highlighted a detachment value about 3.5 times higher than the lime plaster applied on the side of the cork.