Steel Corrosion and Control in Concrete Made with Seawater

Abstract

Aims: The aim of the research is to use seawater to make reinforced concrete. Background: Water scarcity is amongst the biggest problems the world is facing in the 21st century. To reduce the consumption of potable water (PW) in construction industries and to make concrete construction more sustainable, its replacement with seawater (SW) has been explored. Technical literature on this subject is not widely available. Such investigations are necessary for determining suitable remedial measures for the effective utilization of seawater for making sustainable concrete. Objective: In the present study, use of seawater (SW) has been explored as both mixing and curing water in concrete. To counter the adverse effects of seawater on strength and corrosion resistance, use of fly ash (FA) and red mud (RM) as cement replacements in the seawater concrete had been investigated. Method: The possibility of the use of seawater in making concrete has been explored by literature and experimental investigations. The obtained results are discussed in light of the information available in the literature. Various tests were performed such as compressive strength, Half-cell potential, electrochemical impedance spectroscopy and microstructural analysis using SEM and XRD. Result: Results showed higher compressive strength and improved corrosion resistance for seawater concrete (SWC) with FA & RM as compared to potable water concrete (PWC) specimens. SWC specimens without supplementary cementitious materials show lower electrical resistivity and potential more negative than -450 mV indicating severe corrosion. Conclusion: Seawater concrete containing both fly ash and red mud shows improved corrosion resistance and better compressive strength. Combination of fly ash and red mud prevented the decrease in compressive strength at 90 days in SWC also. An appropriate mixture (SW30F5R) of fly ash and red mud significantly reduced corrosion of steel bar in seawater concrete according to HCP and EIS tests, as a result of dense microstructure and increased chloride binding resulting in a reduction of free chloride ions which is responsible for corrosion of steel in concrete. Other: Seawater can be effectively used in concrete by adopting suitable preventive measures. But it still requires further research.

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Comparative study on durability of binary geopolymer concrete

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