Deformation behavior and damage evaluation of fly ash-slag based geopolymer concrete under cyclic tension

Abstract

Geopolymer concrete (GPC) is a potential alternative to ordinary Portland concrete (OPC) owing to its inherent benefits of low-carbon footprint and eco-friendliness. A comprehensive understanding of the deformation behavior of GPC under cyclic tensile loading is crucial to promote its engineering applications. This study first presented a detailed investigation into the nonlinear behavior of fly ash-slag based geopolymer concrete under cyclic tension. The proportions of slag in the precursors of GPC were designed at 20 %, 30 %, and 40 %, respectively, and the test results were compared with those of OPC. The experimental results indicate that the increase of slag content enhances the ultimate tensile strength, ultimate tensile strain and elastic modulus of GPC, but the elastic modulus of GPC is approximately 36 % lower than that of OPC with a similar strength level. The nonlinear characteristics of the stress-strain curves under cyclic tension for GPC and OPC are highly similar, including residual deformation, reloading strain, and stiffness degradation. Furthermore, the cyclic tensile unloading-reloading curve models with explicit functional forms suitable for engineering analysis are established for both GPC and OPC, which show good agreement with experimental data. Damage evaluation and damage localization based on acoustic emission technology broaden the understanding of the progressive failure process of geopolymer concrete under axial tension.