Cementitious versus alkali-activated textile-reinforced mortars combined with mineral wool insulation for strengthening masonry panels exposed to high temperature

Abstract

This study focuses on the experimental investigation of an integrated system that combines seismic upgrading of masonry load-bearing elements with their protection against fire-born high temperatures. Two systems of carbon textile-reinforced mortar (TRM) comprising different matrices were combined with mineral wool panels. The first matrix was a cementitious mortar with polymers based on ordinary Portland cement (OPC), while the second one was an environmentally friendly alkali-activated mortar (AAM) based on ferronickel slag. The study focused on the mechanical performance of retrofitted masonry specimens in terms of shear bond capacity, out-of-plane monotonic and in-plane cyclic bending capacity. Prior to their mechanical testing, some of the retrofitted specimens (both thermally protected and not) were exposed to 600 °C for 1.5 h. It was concluded that: (i) the residual (post-heat) shear bond capacity of both the thermally protected and unprotected masonry-to-TRM joints remains unaffected or decreases in case of prisms furnished with textile-reinforced alkali-activated or polymer-modified mortar overlays, respectively; (ii) exposure to high temperatures bears a moderate negative effect on the flexural response of the TRM-retrofitted-insulated walls irrespective of the matrix type; (iii) textile-reinforced alkali-activated mortar jackets comprise a promising retrofitting option for flexure-deficient walls without any thermal protection means.