The effect of reinforcement ratio on the flexural performance of alkali-activated fly ash-based geopolymer concrete beam

Alkali activated fly ash (AAFA) based geopolymer concrete structure is getting attention due to its eco-friendly construction characteristics and improved engineering properties. However, comprehensive studies on the structural performance of hardened properties of AAFA geopolymer concrete is not well addressed, especially on non-linear fracture behavior. This paper aims to present the reinforcement ratio effect on the flexural performance and non-linear fracture characteristics of alkali activated fly ash based geopolymer concrete beams. Sixteen finite element (FE) and four experimental models were used to study the effect of reinforcement ratio on the flexural performance and non-linear fracture characteristics. Four groups of concrete specimens with an average compressive strength of 19.30 MPa, 32.60 MPa, 38.2,0 MPa, and 41.70 MPa were utilized under this study. To investigate the effect of reinforcement ratio on flexural performance of the beams, reinforcement ratios of 0.03, 0.042, 0.045, and 0.063 were used for each compressive strength class. The result showed that the ultimate load carrying capacity of the beam showed significant improvement by about 36.38% by increasing of reinforcement ratio from 0.03 to 0.063 by keeping the compressive strength of concrete constant. However, it was observed that the effect of compressive strength was not such substantial as reinforcement ratio in enhancing the ultimate load bearing capacity. The experimental result showed that the increase in ultimate load by keeping the reinforcement ratio constant is about 12.20% for different compressive strength. Furthermore, the crack formation in the concrete was highly associated with the tensile reinforcement ratio, i.e., smaller reinforcement ratio led to higher strain growth in the concrete. Moreover, the validation study between the numerical simulation and test results showed a good agreement.