Application of alkali-activated materials (AAM) in seismic and combined energy and seismic retrofitting of beam-type masonry walls: In- and out-of-plane behavior

The application of alkali-activated materials (AAM) based on metakaolin, fly ash and ladle furnace slag in seismic retrofitting of beam-type unreinforced masonry (URM) walls with textile reinforced mortars (TRM) was investigated in this study. Additionally, a combined seismic and energy retrofitting scheme comprising an extruded polystyrene (XPS) thermal insulation, alkali-activated or traditional cementitious mortar and styrene-butadiene rubber (SBR)-coated glass-fiber textile was studied on beam-type URM walls. A total of 12 wall specimens made of perforated fired-clay bricks were subjected to in- and out-of-plane cyclic tests. Seismic retrofitting with AAM-based TRM led to a substantial increase of load-bearing capacity, up to 70 %, while the combined energy and seismic retrofitting increased the energy dissipation capacity by at least 8 times for both in- and out-of-plane loading. Durability of the TRM jackets consisted of SBR-coated glass-fiber textile and AAM mortar was studied experimentally and at the matrix-fiber interface with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). A severe impact of the AAM mortar mix in fresh state on SBR-coated glass-fiber textile was quantified through a set of uniaxial tensile tests and confirmed at a microscopic level. Alkali-activated materials pose a great potential in becoming an effective and environmentally friendly alternative to traditional cementitious materials in structural repair and retrofitting applications. However, to systematically utilize the AAM-based TRM strengthening configurations studied here, the addressed durability issues need to be resolved. • Seismic and combined seismic/energy retrofitting was applied at deep beam-type URM walls. • Cyclic in- and out-of-plane four-point bending tests of URM walls strengthened with AAM- and OPC-based TRM configurations. • Seismic retrofitting with TRAAM increased the load-bearing capacity up to 70 %. • Combined seismic/energy retrofitting increased the energy dissipation capacity 8 times. • Durability of TRM comprising a geopolymer (AAM) mortar and SBR-coated glass-fiber textile was studied.