Mechanical Performance of Compacted Earth Bricks (CEB) Incorporated by Raw and Treated Red Algae Fibers “Gelidium Sesquipedale”

Red seaweed is widely available worldwide and its exploitation for the production of agar products has become an important industry in recent years. In Morocco, the industrial processing of red seaweed generates a large amount of algae fibers waste, which is a source of serious environmental problems. The main objective of this work is to valorize this algae fibers of Moroccan origin as a reinforcement of compacted earth bricks (CEB). These fibers were added to CEB at various ratios ranging from 0.5 to 3% by weight. The introduction of the fibers significantly increases the plasticity of the earth mixture in the fresh state. However, the algae fibers do not significantly alter the manufacturing water content of the CEB. In the hardened state, the inclusion of algae fibers leads to a significant decrease in mechanical properties, is probably due to the voids created by the algae fibers inside the matrix, which leads to poor fiber/matrix adhesion. In this regard, to enhance the mechanical properties of the CEB, various treatments were explored: pre-saturation of the fibers, alkaline treatment by sodium bicarbonate, and double coating treatment (linseed oil and metakaolin). Raw and treated algae fibers were incorporated into CEB with an addition ratio of 1.5% by weight. Compared to the untreated fibers, the pre-saturated fibers show a slight improvement of more than 5% in mechanical strengths. However, the alkali treated and double coated fibers provide a significant improvement of more than 20% in the mechanical strengths of the CEB.