Geopolymer Concrete Columns under Combined Axial Load and Biaxial Bending

Synopsis: Fly Ash based geopolymer concrete is an alternative concrete that uses fly ash instead of cement. It is important to study the performance of a new material in various applications for its use in construction of structures. This paper presents the behavior of geopolymer concrete columns under combined axial load and biaxial bending. Twelve reinforced geopolymer concrete slender columns were tested at different combination of biaxial load eccentricities. The compressive strength of concrete varied from 37 to 63 MPa and the reinforcement ratio was 1.47 % or 2.95 %. No change was observed in appearance of the columns and the cylinders after exposure to varying outside environment under direct sun and rain for more than one year. The failure behavior of the columns was similar to that of Ordinary Portland cement (OPC) concrete columns under biaxial loading. Strengths of the columns were calculated by using the well-known Bresler’s load reciprocal formula and the current Australian Standard for OPC concrete. The mean ratio of the test strength to calculated strength of the columns is found to be 1.18. Thus, the Bresler’s formula which is commonly used for the design of OPC concrete columns resulted in good correlation with test results of the geopolymer concrete columns.