Flexural performance of RC slabs with corroded reinforcement and strengthened using carbon textile-reinforced mortar

Corrosion-induced degradation of reinforced concrete (RC) is a global challenge affecting many existing structures. Repair and strengthening are required to recover their load-bearing capacity, mitigate further deterioration, and extend service life. In this work, the use of textile reinforced mortar (TRM) to repair and strengthen corrosion-damaged slabs was investigated. To this end, the flexural response of one-way reinforced concrete slabs affected by chloride-induced corrosion and strengthened with carbon TRM was evaluated. Four slab specimens were subjected to an accelerated corrosion process in which the longitudinal bars on one half of the slabs reached a nominal 8% mass loss, reproducing the non-uniform corrosion commonly observed in practice. Following deterioration, two of the slabs were repaired and strengthened with two TRM layers composed of carbon textiles and a high resistance mortar with short glass fibres. To improve bond and delay premature debonding, carbon spike anchors were installed, and two anchorage layouts were investigated. Flexural testing was performed using a three-line bending configuration. The strengthened slabs achieved a 32–39% increase in maximum load capacity and a 63–96% increase in the cracking load with respect to the un-strengthened slabs. In addition, TRM strengthening reduced midspan deflections by 48–57% within the service load range. In both anchorage arrangements, spike anchors ensured full activation of the carbon textile. Digital image correlation was used and showed that bond degradation related to corrosion promoted arching action and tension-tie behaviour in the corroded region, leading to stress concentrations and concrete spalling. Analytical estimations of the slabs strength and nonlinear finite element (FE) models were developed to provide additional insight into the observed response. The analytical resistance predictions differed by less than 5% for strengthened slabs, while the FE simulations differed by approximately 2–5% from the experimental strengths, showing good agreement with the test results. Parametric FE analyses on the corrosion level and number of TRM layers confirmed the effectiveness of the strengthening method, showing that even in the studied worst-case scenario of 15% steel mass loss and only one TRM layer, the strengthened slab would exhibit a 7.2% strength increase with respect to an uncorroded slab.