Impact of treated red-algae fibers on physico-mechanical behavior of compressed earth bricks for construction

Red algae, abundant along the Moroccan coast, have fostered an agar-agar industry. However, industrial processing of red algae produces significant fibrous waste, posing environmental challenges. A new challenge is to find sustainable methods for repurposing this fibrous waste. Valorizing red-algae fibers in building materials promotes sustainable development and eco-construction. This study aims to valorize these red-algae residues as fiber reinforcements in compressed earth bricks (CEB). Various mass ratios of red-algae fibers (0.5%-3%) were incorporated into CEB. The addition of raw red-algae fibers to mixtures slightly increased the Atterberg limit values of the earth mixture. A slight adjustment in manufacturing water content was also observed with fiber addition. The incorporation of red-algae fibers did not improve the mechanical strengths of the CEB. Nevertheless, at a 1.5% addition ratio, CEB exhibited compressive and flexural strengths of 4.07 and 0.77 MPa respectively. To enhance mechanical properties, fibers were pre-saturated and subjected to alkaline and double coating treatments. Untreated and treated fibers were added to CEB at an optimal mass addition rate of 1.5%. Pre-saturated fibers showed a slight improvement of 5% in mechanical strength. However, alkali-treated and double-coated fibers offer a significant improvement of 20% in the mechanical strengths of CEB, demonstrating the efficacy of treatments.