Performance enhancement of reinforced concrete exposed to electrochemical magnesium chloride using nano-ferrite zinc-rich epoxy

Abstract

The principal issues with regular reinforced concrete are the deterioration of the bond strength and steel corrosion due to chlorides exposure. In response to treating these issues, a novel hybrid zinc-rich epoxy (ZRE) coating with various percentages of nanoferrite (NF) was created (NF-ZRE). Two concrete mixes were designed, normal (MN) and silica fume (MSF). Each mix had four coating categories. These contain uncoated rebars, ZRE-coated rebars, NF-ZRE (1%) and NF-ZRE (2%) nanoferrite coatings. The specimens were electrochemically accelerated in magnesium chloride (MgCl2) solution in the presence of electric current for up to 21 days to investigate corrosion and bond strength (fb). The results were compared to those of water-cured specimens. The results showed improvements in (fb) for NF-ZRE specimens with 1% and 2% which indicates that preventing the corrosion improved the concrete performance in the presence of the chlorides and the electric current. Energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM) were used to examine the microstructures of MN and MSF subjected to electrochemical chlorides-exposure. After 21 days of electrochemical curing, fb was improved to be 18.9 MPa and 19.9 MPa for MN and MSF, respectively. The results for 28-days of water-cured specimens were 15.4 MPa and 17.4 MPa, respectively. The SEM and EDAX results showed that cement-based materials containing chloride ions improve pore structure, reducing pore size, increasing tortuosity, and decreasing porosity and permeability.