Behaviour of RC beams and mechanical properties of geopolymer concrete

The effects of substituting ordinary Portland cement (OPC) with fly ash and ground granulated blast furnace slag (GGBFS) on fresh and mechanical properties of concrete and the behaviour of reinforced concrete (RC) beams are explored. A control mix and two geopolymer concrete (GPC) mixes using 50% GGBFS and 50% fly ash for the first and 70% GGBFS and 30% fly ash for the second were used to cast 189 samples. Testing revealed that GPC samples reached the design compressive strength after 56 days of curing. Moreover, GPC demonstrated better durability when compared to conventional concrete. Upon testing of RC beams, it was concluded that GPC exhibits more ductility. Finally, GPC RC beams experienced the expected failure mode, i.e., flexural testing samples experienced a tension-controlled failure mode and shear testing samples exhibited a diagonal crack that propagated from the loading point to the support.