Effect of reinforcement ratio and textile pre-impregnation on the mechanical properties of flax textile reinforced sulfoaluminate matrix

This study evaluates the effect of reinforcement ratio and textile pre-impregnation on the tensile behavior of flax textile, embedded in an inorganic CSA matrix (sulfoaluminate cementitious matrix), known as Fabric Reinforced Cementitious Matrix (FRCM). Two reinforcement ratios of (3 and 6%) and two impregnation techniques (polymeric and mineral) are applied. Direct tensile tests are conducted on FRCM specimens as well as on bare flax textiles featuring three configurations: NP (non-impregnated), PP (polymeric-impregnated), and PM (mineral-impregnated), between 1L (one layer) and 2L (two layers) of flax textile. The results show a direct correlation between the reinforcement ratio and the enhancement of mechanical properties, with a notable 44% increase in mechanical strength observed for NP FRCM specimens between 1L and 2L of flax textile. Mineral pre-impregnation enhances yarn-cement matrix bonding inside FRCM, while FRCM specimens with polymeric-impregnated textiles have limited influence on the mechanical properties due to premature failure. Polymeric impregnation has a pronounced effect when applied to bare flax textiles, with PP flax textiles demonstrating exceptional mechanical strength and rigidity, reaching up to 480 MPa and 37 GPa, respectively. In contrast, this effect was mitigated when employing PP textiles in FRCM specimens, where the lowest fabric efficiency reached 12% for the 2L.PP configuration suggests significant chemical incompatibility between epoxy resin and CSA matrix. Mineral-impregnated specimens display consistent efficiency regardless of reinforcement ratio, suggesting a novel and homogeneous distribution of cement matrix particles within the yarns of textiles. Two distinct failure modes of FRCM are observed in this study, a delamination for PP configurations and a fiber pullout for NP and PM configurations. No effect of reinforcement ratio is remarked on the failure mode. The cracking mode in PM FRCM configurations showcased improved aesthetics, durability, and elongation after rupture (6.28%). As a result, 2L.PM FRCM is the best configuration in terms of mechanical strength, rigidity, ductility, and durability.