Strength and Behaviour of Small-Scale Reinforced High Calcium Fly Ash Geopolymer Concrete Beam with Short Shear Span

Abstract

The small-scale reinforced high calcium fly ash geopolymer concrete beams with short shear span were studied in this research. Reinforced concrete beams with 150x150 mm2 cross-section and 530 mm in length were used for tests. Conventional reinforced Portland cement concrete beams (RC) with designed concrete compressive strengths of 35, 45 and 55 MPa and high-calcium fly ash geopolymer reinforced concrete beams with similar strength were tested. The geopolymer concretes (GC) were designed with alkaline liquid to fly ash ratio (L/A) of 0.5, sodium silicate to sodium hydroxide (S/H) ratio of 1.0 and two sodium hydroxide (NaOH) concentrations of 10M and 15M. Two temperatures of 23 and 60 °C were used for curing geopolymer reinforced concrete (GRC) beams for 24 hr, while RC beams were moist cured at 23 °C. The maximum sustained moment and shear were compared with the predicted values from the RC-design standard. The results showed that the failure patterns of small GRC beams were different to that of normal RC beam. The small GRC beams failed in flexure whereas the similar small RC beams failed in shear. However, the GRC beams were able to sustain higher shear and moment than the values obtained from the design code. The different in failure mechanism was probably due to the different in modulus of elasticity of geopolymer concrete and normal concrete.