SEISMIC RETROFIT OF RC SHORT COLUMS WITH TEXTILE REINFORCED ALKALI-ACTIVATED OR CEMENT-BASED MORTARS

The effectiveness of textile reinforced mortars (TRM) utilized in a form of jacketing overlays applied on short, shear-critical RC columns is investigated experimentally and verified analytically in this study. Moreover, the possibility of replacing the standard ordinary Portland cement (OPC) matrix with an alternative alkali-activated material (AAM) in the TRM retrofitting technique is explored. A total of seven RC columns were tested, at a scale of approximately 2/3, with the shear span – to – height ratio of 1.5. Four out of seven specimens were designed to be more ductile with closely spaced shear reinforcement, while the rest had their stirrups positioned at larger spacing. Both series of columns were retrofitted with two and four layers of TRM jacket overlays, made of uncoated carbon textile and AAM or OPC-based mortar, and subjected to cyclic loading combined with a constant vertical load. While control (unretrofitted) specimens exhibited a brittle failure, the retrofitted ones performed significantly better in terms of deformation capacity, with a clear shift of the failure mode towards shear-flexure. The load capacity of jacketed columns was governed by yielding of longitudinal reinforcement. An important result is that AAM-based TRM jacketing is not inferior by any means to its OPC-based counterparts.