Q: What's the best way to specify epoxy-coated reinforcement for construction projects?

A: A good specification will help assure that high quality epoxy-coated reinforcement is supplied to the project. Although many agencies have their own variations, CRSI recommends that the standard ASTM specifications be used.

• ASTM A775/A775M (Coating Application and Powder Qualification)
• ASTM D3963 (Fabrication and Field Requirements, Repair Material Qualification)

Make sure that proper specifications are included for all stages of the project: coating application, fabrication, field handling, and material pre-qualification.

Q: How much cost does epoxy coating add to the cost of steel reinforcement?

A: As with everything costs vary but as a rule of thumb one that is frequently used is that epoxy coating will only add about 25 percent to the installed price of reinforcement. Actual costs depend on location, job complexity, quantity, and proximity of suppliers.

For most structures, this equates to only a one to two percent increase in the overall structural cost.

Q: Should the bottom mat of steel on a bridge deck or a parking garage be epoxy-coated along with the top layer?

A: Researchers in an FHWA study concluded that coating the bottom mat reduces the area of steel that is available to serve as a cathode in a corrosion reaction, thus slowing the rate of corrosion. Another reason to coat the bottom mat of steel is that chlorides can quickly penetrate a cracked slab and reach the bottom mat, even when high quality concrete is used. There are numerous bridge decks built with epoxy coated bars in the top mat and uncoated bars in the bottom mat. These uncoated bars are now corroding.

CRSI recommends the practice of using epoxy-coated bars throughout the area of the structure which is exposed to the corrosive environment. Using epoxy-coated bar throughout makes it more difficult for corrosion to initiate and if it does occur it slows the rate as well.