Tensile and Textile–Mortar Bond Behavior of Bamboo (Bambusa blumeana J.A. & J.H. Schultes) Textile-Reinforced Mortar (TRM): Influence of Yarn Ply Configuration and Epoxy Coating

Bamboo textile fiber (BTF) is a renewable alternative to synthetic textiles in textile-reinforced mortar (TRM), but the effects of yarn architecture and coating on its tensile and bond behavior are not well established. This study tested four BTF-reinforced TRM configurations with a 15 × 15 mm grid: textiles woven from single-ply (SP) and two-ply (DP) yarns, each in dry and epoxy-coated (SPI, DPI) conditions. Twenty direct tensile coupons and twenty textile–mortar bond specimens bonded to concrete substrates were tested under displacement control. The effects of ply configuration, coating and their interaction were evaluated by two-way ANOVA, and the coated yarn surface was examined by scanning electron microscopy. Epoxy coating significantly increased peak strain and toughness (p < 0.001) and peak tensile stress (p = 0.008), with the largest effect for the two-ply textile, for which toughness increased from 0.09 to 0.54 MJ/m3 and peak tensile stress from 16.11 to 28.36 MPa. Ply configuration (p < 0.001) and coating (p = 0.018) both significantly increased the peak textile-normalized bond stress, from 3.52 MPa (SP) to 9.65 MPa (DPI), with no significant interaction; all bond specimens failed by textile rupture, so these values are lower bounds. DPI gave the highest peak strain, toughness and peak bond stress, supporting its selection for structural-level validation.