Abstract: The mechanical and deformation properties under cyclic loading and unloading with variable amplitude are crucial for concrete structures under sulfate attack. The evolution of the mechanical properties,deformation properties and dissipation energy of concrete specimens under chemical erosion immersed in 10%,15% and 20% sodium sulfate solution for 5 and 7 months in advance was examined via uniaxial compression cyclic loading and unloading test with variable amplitude. Results demonstrated that with the increase of sodium sulfate concentration and erosion time,the strength of the specimen declined,and the number of cycles at failure decreased. The cumulative residual strain increased with the rising of loading strain,and such increment intensified continuously. The loading strain difference was always larger than the cumulative residual strain difference,but approached closer gradually with the proceeding of cyclic loading and unloading. The dynamic elastic modulus and plastic deformation rate both increased with the cyclic loading. The dissipated energy also increased with the cyclic loading,and especially boosted in the later stage.

Key words: concrete, sulfate attack, cyclic loading and unloading with variable amplitude, mechanical properties, deformation properties