Design and properties of cement coating with mussel shell fine aggregate.

• Mussel shells are a by-product converted into fine aggregate after a low environmental impact process. • Shell aggregate disturbs microstructure and pore size distribution of cement coatings. • Particle shape and shell composition are the main characteristics affecting coating properties. • The use of 25% mussel shell leads to accurate surface and base layer coatings. The production of farmed mussels amounts to millions of tonnes across over 40 countries. Shell waste resulting from this production has a very significant environmental impact. In Galicia, mussel shell waste is transformed, using low impact heat treatment, into a by-product that can be used as an aggregate. This research investigates cement-coating mortars where conventional aggregate is partially replaced with mussel shell aggregate. Reference mortars and mortars with mussel shell sand replacing conventional sand at different rates: 25%, 50% and 75% have been tested. Results show the feasibility of mussel shell in cement coatings at an optimal replacement rate of 25% of the conventional aggregate. [ABSTRACT FROM AUTHOR]