Vermont. Agency of Transportation. Materials and Research Section

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The Vermont Agency of Transportation undertook a simple experiment to determine the corrosion

resistance ability of various reinforcing steels (rebar) that may be used in bridges and other concrete

structures. Eight types of rebar were used in the study,

including: black, MMFX2, epoxy coated, Z

-

Bar,

stainless clad, high nickel stainless steel, high manganese stainless steel, and a duplex stainless steel.

Rebar samples were subjected to a 3% sodium chloride salt water solution bath three days a week for

ei

ght hours. When not submerged, samples were left to dry under standard temperature and

pressures. Samples went through this procedure for a total of 260 cycles, which was equated to an

approximately 10 year outdoor lifecycle under Vermont’s climatic cond

itions. Samples were measured

for mass, diameter, and coating thicknesses prior to, periodically during, and at the completion of their

exposure testing.

Results prove that each type of rebar show varying degrees of corrosion resistance to sodium

chloride.

Black bar showed not only extensive corrosion, but it also began rapidly from the onset of the

immersions, while epoxy coated bars (ECR) showed adequate resistance to corrosion. Some ECR

bars were intentionally cut and not repaired for the stud

y showed a considerable increase in corrosion

over intact bars. Bars that are designed to further combat construction damage, Z

-

Bar, stainless

-

clad,

and solid stainless steels, exhibited far greater corrosion resistance

US Transportation Collection