Mussel shells: A canning industry by-product converted into a bio-based insulation material

Abstract

The canning industry in Galicia produces 25 thousand tonnes of mussel by-product (i.e. unconsumed shells) per year, having a significant environmental impact. Mussel shell becomes suitable for different uses after undergoing heat treatment such as poultry feed or bedding, etc. However, other end uses for this by-product must still be explored. Building insulation material (for instance expanded polystyrene, extruded polystyrene, polyurethane, etc.) has a significant harmful effect on the environment, which is especially seen when analysing its entire life cycle (use of large amounts of energy and water for production, difficulty recycling or reusing waste in the event of demolition or refurbishment, etc.). The aim of this research is to prove the feasibility of using mussel shell as a building solution. Mussel shell has been found to have thermal and acoustic characteristics suitable for using it as building insulation material. Mussel shell confined inside an enclosed space (e.g. a wooden box) has a thermal conductivity similar to that of a light conifer wood, so it can be considered a material with low thermal conductivity. Furthermore, several acoustic studies indicate that a section of confined mussel shell displays a behaviour similar to that of commercialised insulation material. The embodied energy of mussel shell as a loose-fill material is similar to that of other bio-based insulation materials. The main goal of this paper is to demonstrate that it is possible to design mussel shells building solutions, that actively participate in environmentally responsive architecture.