Experimental and analytical study for shear strengthening of reinforced-concrete beams using a prefabricated geopolymer–mortar panel

This study investigated the performance of geopolymer–mortar panels (GMPs) in improving the shear capacity of reinforced-concrete (RC) beams. A GMP with a thickness of 15 mm was prefabricated and fixed to the shear span of beams using mechanical anchors. Five RC beams were constructed and tested under a four-point bending monotonic load: one unstrengthened, three strengthened with a GMP, and one strengthened with a Portland-cement-mortar panel. The investigated parameters included (a) anchor-bolt spacing, (b) presence of a wire mesh, and (c) binding material types. The results indicated that the GMP is an effective technique for improving the shear capacity of RC beams. The maximum gain in the shear capacity of the strengthened beams ranged from 14.1% to 34.9% with respect to the unstrengthened beam. Moreover, the results suggested that the failure mode of the beam changed from brittle to ductile failure if an anchor bolt spacing of 200 mm and wire mesh were used at the GMP. Based on these findings, the GMP can be used as an alternative method for shear-strengthening RC beams in building applications owing to its high strength and ductility. Finally, an analytical model based on the simplified-modified–compression-field theory model was proposed to predict the shear capacity of RC beams strengthened with the GMP. The analytical model was in reasonable agreement with the test results.