Characterisation at different elevated temperatures of thermomechanical and residual tensile behaviours of refractory mortar reinforced by glass textiles

This study investigates the thermomechanical and residual tensile behaviour of a Textile Reinforced Concrete (TRC) composite which is made up of a refractory matrix and an alkali-resistant (AR) glass textile grid. An experimental program was conducted using two distinct loading protocols: thermomechanical (TM) tests, involving simultaneous heating and loading, and residual resistance (RR) tests, where specimens were heated, cooled to ambient temperature, and then loaded. Tests were performed across a temperature range of 25 °C–600 °C. Key findings reveal a significant divergence in material performance depending on the loading path. Under TM conditions, the ultimate tensile strength showed a slight increase at 300 °C before declining, while RR tests demonstrated a notable strength enhancement after exposure to 75 °C, 150 °C, 450 °C, and 600 °C. Furthermore, the maximum axial strain at failure, which is mostly subjected to the deterioration of the polymer coating on the textiles, differed markedly between the two protocols, particularly in the 75 °C–450 °C range. The study also analysed the temperature-dependent evolution of initial and post-cracking stiffness, highlighting the complex interplay between matrix degradation, fibre weakening, and interfacial damage. Cracking patterns further differentiated the two regimes, with RR specimens exhibiting improved resistance to thermal damage. These results underscore the critical importance of considering both thermal history and loading conditions for accurate performance prediction and design of TRC structures in high-temperature environments.