Flexural Behaviour of Reinforced Concrete Beams Strengthened with Textile-Reinforced Strain Hardening Geopolymer Composites (TR-SHGC)

Abstract This study aims to assess the behaviour of Reinforced Concrete (RC) beams strengthened in flexure with a composite layer of strain-hardening geopolymer composites (SHGC) and Fiber Reinforced Polymer (FRP) textiles. One unstrengthened reference beam and ten strengthened beams were tested under static loading conditions. The tested beams had similar dimensions: a total depth of 250 mm, a width of 200 mm, a total length of 2400 mm and a clear span of 2200 mm. The textile-reinforced mortar (TRM) strengthening was applied in the form of either externally bonded (EB) or hybrid near surface embedded and externally bonded (NSEEB) technique. Thus, before the strengthening applications, longitudinal grooves were created in the soffit of nine beams: in eight beams, a groove with a depth of 25 mm and a width of 100 mm was created, whereas, in one beam, two grooves with a depth of 25 mm and a width of 50 mm were made. This study compares three types of strengthening mortars: ordinary cementitious mortar (OM), strain-hardening cementitious composites (SHCC), and SHGC. Embedded into the mortar, either null, one, two or three layers of textile reinforcement were provided. The mortar reinforcement was either steel, GFRP or CFRP. The test results showed that the application of SHGC in the form of the NSEEB technique increased the ultimate load and ductility of the strengthened beams. With the strengthening of NSEEB–SHGC, the improvement in the ultimate capacity reached about 67%. Finally, a flexural capacity model was proposed that agreed with the experimental results.