Brown algae: Sargassum sp. and Lobophora sp. incorporation in magnesium oxychloride cement

Abstract

The massive arrival of brown algae in the Caribbean is a current problem affecting some tourist countries ecosystems and economies. Hence, it is necessary to find alternatives to harnessing algae in different applications, e.g., in the construction industry. Herein, it is proposed to analyze the feasibility of harnessing two types of brown algae: Sargassum sp. and Lobophora sp. collected in the Caribbean as additives in Magnesium Oxide Cement (MOC). Three loads of algae (5, 7, and 10 %wt.) were incorporated into the pastes to investigate their effect on its physicochemical properties. The addition of algae resulted in a more compact microstructure; meanwhile, the crystallization of the 5 Mg(OH)₂·MgCl₂·8H₂O (phase 5) in the MOC was not affected. The incorporation of the algae in the paste improved the moisture stability of the pastes but decreased their mechanical performance due to a higher surface area and lower pore size. In summary, this work demonstrated that harnessing brown algae such as Sargassum sp. and Lobophora sp. is a feasible alternative to valorize this plague to design more sustainable building materials.