Elaboration and characterization of earth-sand adobe bricks reinforced by Alfa fibers

Abstract The main aim of this work is to investigate the effect of Alfa fiber length and quantities on linear shrinkage, mechanical strength, and failure manner of the reinforced material as compared to the unreinforced mix, by the incorporation of Alfa fibers in earth-sand building material. The earth-based composite consisted of a mixture of earth 60 wt% and sand 40 wt% reinforced with various lengths and rates of fibers extracted from the Alfa plant. First, fibers' tensile strength and water absorption were evaluated to understand their behavior. Moreover, tests have been conducted on prismatic specimens 40x40x160 mm3 with different cutting lengths (1, 2, and 3 cm). These fibers were added to soil at various weight ratios (1%, 1.5%, and 2%). The results have indicated that the incorporation of 2%wt of fibers reduced the unit weight from 1849 kg/m3 to 1632 kg/m3, which results in a slight material. The experimental investigation has shown also that the unreinforced adobe specimens had a high linear shrinkage rate and low mechanical behavior compared to fibrous samples. Specially, specimens with a higher fiber content of 2%wt of 3 cm length were revealed to be the most suitable in terms of mechanical behavior. Moreover, fibers prevent and delay crack propagation, where fiber length and content play a principal role in crack attenuating. Despite the improvement of mechanical properties, the microstructural observation of the reinforced composite shows poor fiber/matrix adhesion, which affects negatively the compactness of the adobe specimens.