Impact of mussel shell aggregates on air lime mortars. Pore structure and carbonation

Abstract

[Abstract:] Galician “Rías”·conditions (extension, water temperature …. ) enable the production of excellent quality cultured mussels. This leads Spain to be the third producer country in the world. Cannery industry (35% of the total cultured mussel production) generates 25000 tons of mussel shell waste per year. Hence, it is necessary to find a sustainable use for this material. The purpose of this work is to verify the most significant changes in the properties of air lime coating mortar when replacing limestone sand with mussel shell sand. Two different air limes have been used: non-aged hydrated commercial lime powder and 10 month-old slaked lime putty. Reference mortars and mortars with mussel shell aggregate as a substitute for limestone aggregate at different rates - 25%, 50% and 75% - have been tested. The behaviour of mortars at the age of one year from kneading has been studied. Studies show that mussel shell increases the pore volume of air lime mortar mixtures, which means a reduction in the mortar's workability and density. The poor paste-aggregate cohesion of mussel shell particles in the air lime matrix worsen the mortar mechanical strength results, which is confirmed by ultrasound test results. Carbonation at this age and hygric behaviour are properties that improve with mussel shell content.