Tracking the Observations of Volume Deformation of Concrete under Sulfate Attack through 3D Digital Image Correlation

Abstract

Abstract In this study, three-dimensional digital image correlation was used to characterize the nonuniform volume deformation of concrete under sulfate attack. Based on the test and results, it was determined that the displacement distribution of the concrete exposed to sulfate attack was inhomogeneous, and the expansion of the concrete in the sodium sulfate (Na2SO4) solution was greater than that in magnesium sulfate (MgSO4). Thus, the distribution of nonuniform expansion and the mechanisms of sulfate attack were identified. Notably, sample expansion did not increase linearly with the content of hydrates such as ettringite and gypsum. The volume expansion of the concrete in the Na2SO4 solution grew slowly when the content of corrosion products was low and developed rapidly with further increases in corrosion products. The volume expansion of the concrete in the MgSO4 solution grew slowly with low corrosion product content, and then the volume expansion slowed down with the accumulation of corrosion products.