Textile-Reinforced Alkali-Activated Mortar for In-Plane Shear Capacity Improvement of Masonry Before and After High Temperature Exposure

In view of the pressing need for strengthening old masonry structures, while considering the importance of reducing CO₂ emissions in the construc-tion sector, masonry retrofitting techniques with environmentally friendly (i.e., non-cementitious and non-corroding) materials need to be studied and developed. This paper discusses the mechanical performance of historical brick single-leaf masonry elements strengthened with a textile reinforced alkali-activated mortar (TRAAM). Ferronickel waste slag was used as the precursor of the TRAAM matrix, whereas the textile reinforcement consisted of carbon fibers. The mechanical performance was determined experimentally on the basis of diagonal compres-sion capacity of wallettes. Apart from normal conditions, the mechanical prop-erties were also determined after fire exposure. Two fire tests were performed, with a high heating rate in the first stage, a steady-state stage, and a cooling stage. The maximum temperatures reached at the TRAAM overlays were in the order of 300 °C and 550 °C, respectively, for the two tests. The results showed a significant increase in the shear capacity of the strengthened walls compared to non-strengthened ones, in ambient conditions. Fire exposure of the strengthened specimens did not lead to a decrease of the shear capacity compared to the unex-posed strengthened specimens. This was attributed to the superb fire performance of the ferronickel slag based TRAAM.