Experimental investigation and design-oriented model for concrete column confined with textile reinforced geopolymer composites

The present study deals with an experimental investigation on concrete columns (small-scale) confined with TRM (textile reinforced mortar) having geopolymer-based matrix. Two different types of fibers for the textile were used, namely basalt and glass, while the number of layers varied ranging between 2 and 4. Furthermore, hybrid textile confinement, obtained by installing glass textile inner layer coupled with basalt textile outer layer, was tested. In addition, a pilot sample was also considered with geopolymer matrix-only confinement. From the experimental results, the confinement was found to be effective in increasing axial strength proportionally to the number of textile layers. An increase in the compressive strength of 43.7% and 47.7% was recorded for the four layers of glass and basalt textile, while a maximum axial ductility of 2.18 and 2.19 was obtained for three and four layers of glass and basalt textiles, respectively. Furthermore, both the hybrid textile and the matrix-only configurations have demonstrated a significant improvement in strength. Based on the experimental findings, a theoretical model was empirically calibrated to predict the compressive strength of TRM-confined columns. While the existing models on TRM generally neglect the matrix's contribution according to the FRP-based (fibre reinforced polymer) theory, the present study reports and discusses a new design-oriented model considering both the confining matrix and textile effects.