Tensile, bond and flexure strengthening response of textile reinforced mortars for reinforced concrete structures

Abstract Textile reinforced mortars (TRM) are a promising solution for strengthening concrete structures. In this paper, the mechanical response TRM composites incorporating coated carbon and basalt textiles combined with mortars based on calcium sulfoaluminate cement (CSAC) and ordinary Portland cement (OPC) was investigated, together with the flexural performance of carbon TRM-strengthened reinforced concrete (RC) beams. Tensile response and bond behaviour to concrete were studied using clevis grip and single lap shear configurations, respectively. TRM with CSAC mortar achieved tensile performance comparable to OPC TRM. In bond tests, carbon TRM mainly failed by matrix-textile debonding, with weaker bonding when CSAC was used, while basalt TRM failed by fibre rupture with no significant differences between mortars. A bond model with a trilinear cohesive law was proposed, being able to reproduce the single-lap shear force-slip response and identify an optimal bond length beyond which additional strength gains are minimal and friction-controlled. Three-point flexure tests were conducted on beams strengthened with carbon TRM, and the use of spike anchors was examined. Companion parametric finite element analyses were performed to gain further insight into the flexural response, with the material and bond response of TRM modelled according to the data obtained from tension and single-lap shear tests. Flexural tests and numerical analyses displayed that failure was dominated by concrete crushing without full textile utilisation. Additional numerical and theoretical analyses suggest that external/internal reinforcement ratios above 7.3% can deliver flexural strength increases greater than 10%.