Three-dimensional characteristics of steel corrosion and corrosion-induced cracks in magnesium oxychloride cement concrete monitored by X-ray computed tomography

Abstract

We investigated corrosion-induced crack formation of magnesium oxychloride cement concrete (MOCC) in saline soil. Accelerated corrosion of steel in MOCC occurred through an improved galvanostatic accelerated test. X-ray computed tomography, used to scan the MOCC after curing for 14 days, revealed surface cracks of 0.11 mm, 0.25 mm, and 0.44 mm. Steel corrosion, corrosion distribution and corrosion-induced cracks were investigated, using scanning electron microscope (SEM) study the interface transition zone of MOCC. Results show a good linear relationship between steel volume loss and an increase in crack width; a good exponential relationship between an increase in corrosion-induced crack volume and an increase in crack width; and a good exponential relationship between steel volume loss and an increase in the volume of corrosion products. Corrosion-induced cracks do not necessarily form in the direction of the corrosion distribution. The product of the interfacial transitional zones (ITZs) is needle-shaped, which causes the formation of a weak surface in the ITZs so that corrosion-induced cracks usually develop along those zones.