This reference provides a detailed resource covering all aspects of galvanized reinforcing bar. Both serviceability and durability aspects are well covered, with all the information needed maximize the life of structures constructed from it. Containing an up-to-date and comprehensive collection of technical information and data from world renowned authors, it is a valuable source of reference for academics, researchers, students and professionals. Read the summary.

Reinforced concrete is one of the most widely used modern construction materials.  It is inexpensive, readily available, has a range of attractive properties and characteristics and is suitable for a variety of building and construction applications. It is also used in a number of exposure conditions, which in some cases highlights one of the main weaknesses of reinforced concrete: the potential for the steel reinforcement (rebar) to corrode, resulting in staining, cracking and failure of the surrounding concrete.  This brochure highlights the performance of galvanized rebar in concrete along with projects that have benefited from its use.

Authors:  O. A. Kayyali and S. R. Yeomans
Concrete beams reinforced with black, epoxy-coated, or galvanized steel were tested to failure in flexure and the slip of the reinforcement was monitored.  While there was clear evidence of the influence of bar deformations on the bond capacity of beams reinforced with smooth compared to ribbed black steel bars, the majority of the work concentrated on comparing the load-slip behavior of ribbed bars as affected by the presence of surface coatings.  Overall, the results of this work indicated that there was no significant loss in bond with the use of galvanized bars, though a significant reduction was observed with epoxy-coated bars.

Author:  S. R. Yeomans
Further studies of the characteristics and properties of fusion-bonded epoxy-coated steel reinforcement and hot-dip galvanized reinforcement have been undertaken.  The comparative corrosion performance of black, galvanzed, and epoxy-coated reinforcement was investigated in which the influence of exposed cut ends of coated reinforcement and the repair of cut ends was examined.  Pullout testing of black, galvanized, and epoxy coated plain rebar was also done, as well as pullout tests using galvanized plain reinforcement in which varying amounts of chromate ions were added to the concrete via mix water additions.  Where the cut ends of coated reinforcement were repaired, the epoxy-coated bars showed many sites of local breakdown of the repair and corrosion of the underlying steel.  In contrast, the repairs to the galvanized bars performed very satisfactorily with little or no evidence of breakdown of the repair even in the wet and dry salt water environment.

Author:  S. R. Yeomans
The corrosion of galvanized reinforcement in concrete is a multi-stage process.  After a generally long period to the initiation of corrosion, dissolution of the galvanized coating commences with the loss of the outer pure layer of zinc, followed by slow dissolution of the underlying zinc-iron intermetallic layers.  Corrosion of the parent steel does not commence until the zinc alloy layers are completly lost from extensive areas of the bar surface.  This process results in the well documented delay int he appearance of corrosion of zinc coated steel reinforcement in concrete.  The zinc corrosion products appear to cause little or no disruption to the cover concrete and have been observed to fill microcracks and small voids in the matrix, resulting in a an apparent densification of the cement matrix, at distances up to 0.5 mm from the bar interface.

Authors:  M. C. Brown and R. E. Weyers
The corrosion protection service life extension provided by epoxy-coated reinforcement (ECR) was determined by comparing ECR and bare steel bars from 10 Virginia bridge decks buildt between 1981 and 1995.  Altogether, 141 drilled cores, 4 inches in diameter, were employed in this study.  The corrosion service life extension attributable to ECR in bridge decks was found to be approximately 5 years beyond that of bare steel and, therefore, ECR is not a cost-effective method of corrosion prevention for bridge decks.

Author:  T.J. Kinstler
Experimental and anecdotal evidence have shown the efficacy of galvanized reinforcing steel in concrete applications.  However, the mechanism for this performance has not been collectively explored.  This paper reviews significant experiences with galvanized rebars, and synthesizes these experiences with a newly reported investigation into a paradigm which is consistent with demonstrated field and laboratory behavior.  The superior performance of galvanized bars versus balck bars results from a higher threshold for corrosion initiation, reduced corrosion kinetics, and a lowering of stresses induced in the concrete as a result of the mobility of zinc corrosion products.

This 16-page publication from the American Galvanizer’s Association discusses rebar corrosion, hot-dip galvanizing,  and how galvanized rebar performs in concrete including design, specification, fabrication, and installation concerns.