Considerations on Alkalinity in the Use of Bivalve Shells for the Production of Artificial Reefs for the Galician Estuaries

One of the important services of the marine ecosystems in the region of Galicia is the production of bivalve mollusks. After harvesting, it is necessary to purify the mollusks, and this purification process generates waste due to the mortality of individuals. The proposal is the conversion of this waste (calcium carbonate in its allotropic varieties of calcite and aragonite) into raw materials to be included in the production of green type artificial reefs (ARs), aimed at modifying coastal ecosystems and increasing their production in a sustainable way. Seeking the sustainability of the materials employed in ARs it is sought that the pH of the concrete is similar to that of the marine habitat. By means of mechanical tests, after different periods of permanence of the concrete specimens under immersion in seawater, the leached products are analyzed by means of instrumental chemical analysis techniques, determining their pH. With this study of alkalinity, the convenience of replacing 20% of coarse aggregates in the composition of the concrete with residues of shells of some of the varieties of mollusks collected in Galicia is characterized.