Stress-strain constitutive model of concrete corroded by saline soil under uniaxial compression

Abstract

Abstract Stress-strain constitutive relationship is one of the basic mechanical properties of concrete materials, and the stress-strain relationship of concrete subjected to salt corrosion has changed significantly. Saline soil in Western China has the characteristics of many kinds of salt and high concentration, which makes the damage to concrete more serious. In this paper, the uniaxial compressive stress-strain constitutive relation of corroded concrete in saline soil area of Western China is studied, and the constitutive model based on ion diffusion, chemical reaction and mechanical analysis was also given. Firstly, the causes and mechanisms of the change of stress-strain curve of corroded concrete were analyzed via the stress-strain curve, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and porosity. Then, the corroded concrete specimens were divided into three parts from the outside to the inside, namely, the corrosive damage part, the corrosive enhancement part and the non-corrosive part. Combined Fick's diffusion law and chemical reaction, the formulas for calculate the critical failure depth and the internal expansion stress were given. The corrosion effects of the corrosive damage part and the corrosive enhancement part were expressed by the critical failure depth and the internal expansion stress respectively. Finally, based on the meso-statistical parallel bar constitutive model of non-corroded concrete, a stress-strain constitutive model of corroded concrete in saline soil region of Western China was established considered the corrosion effect.