Shear tests on reinforced slag-based geopolymer concrete beams with transverse reinforcement

Although various studies have been performed on alkali-activated cement or geopolymer concrete (GC) in material level, a limited research literatures are available on the structural performance of reinforced GC members. To investigate the shear behavior of reinforced slag-based GC beams, beam shear tests were performed on 18 reinforced slag-based GC beams and 3 conventional reinforced concrete (RC) beams. The test parameters were the concrete type, concrete strength, longitudinal reinforcement ratio, longitudinal bar strength, shear span-to-depth ratio, and beam depth. The test results showed that the shear strength and failure mode of GC beams was comparable to those of RC beams. On the other hand, GC beams were vulnerable to the cracking resistance, which degraded the cracking load corresponding to the allowable crack width. As the shear span-to-depth ratio decreased, the normalized shear strength provided by GC was significantly increased. Further, the contribution of concrete strength f_c′ to the shear strength of GC beams was affected by (f_c′)^0.65. The current design codes were applied to the test results including existing experimental studies, which underestimated the test results. On the other hand, the existing shear strength model based on compression zone depth predicted well the test results of slag-based and fly ash-based GC beams.