Evaluation of the impact of corrosion of hot-dip galvanized reinforcement on bond strength with concrete – A review

Published Date
1 February 2017, Vol.132:271–289, doi:10.1016/j.conbuildmat.2016.11.096

Review

Author

Petr Pokorný ^a,,

Petr Tej ^a

Milan Kouřil ^b

• aKlokner Institute, Czech Technical University in Prague, Prague, Czech Republic
• bUniversity of Chemistry and Technology Prague, Prague, Czech Republic

Received 30 December 2015. Revised 12 October 2016. Accepted 20 November 2016. Available online 9 December 2016. 

Highlights

• This review article describes in detail the impact of corrosion of hot-dip galvanized steel on bond strength with concrete.
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  This work focuses on the influence of all aspects (not only corrosion induced aspects) of the development of bond between hot-dip galvanized steel and concrete.
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  To evaluate the extent of effective corrosion protection, investigations evaluating the corrosion behavior of galvanized steel in fresh and hardening concrete must be re-opened.

Abstract

This review focuses on the effect of initial corrosion of hot-dip galvanized reinforcement in both fresh and curing concrete on total bond strength.

Corrosion behavior of hot-dip galvanized steel is studied in detail in both alkaline solutions without calcium cations and model pore solutions (with Ca²⁺). Relation between pH and resulting extent of corrosion attack on coating is also discussed. The effect of top layer of coating, consisting of various intermetallic phases on corrosion resistance is also discussed.

Regarding the standardized bond strength test procedures, the effects of hydrogen evolution on porosity of adjacent cement and bond strength of galvanized steel and concrete were analyzed. Negative effect of zinc corrosion products is described – concrete curing and hardening of concrete is retarded in their presence, their growth can cause local disintegration.

Close attention is also given to eventual surface modification of galvanized reinforcement aimed at reducing the negative effect of reinforcement corrosion on bond strength (chromate, phosphate, organosilane and other coatings).

The review points out many contradicting results and therefore the fact that real consequences of galvanized reinforcement corrosion are not, even at present day, known. Use of galvanized zinc coatings for protection of conventional steel reinforcement cannot, to this day, be considered clearly beneficial and research regarding the topic to be finished.

Keywords

Corrosion steel in concrete

Epoxy coated reinforcement

Hot-dip galvanized reinforcement

Fe–Zn intermetallics

Bond strength

Pull-out test

Beam test

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