Q.: The engineer for our parking garage repair job required us to paint an epoxy coating on some of the exposed bars before placing a latex modified concrete overlay. Is this really necessary?
A.: The suppliers of latex modifiers assure us that a properlv installed overlay of latex modified concrete effectively protects against corrosion and that the epoxy is not necessary. They seem to have enough field experience to support their claims. However, designers of parking structures, particularly in municipal work where maintenance budgets are limited, frequently take a "belt and suspenders" approach. At times they also specify corrosion-inhibiting admixtures in the concrete surrounding epoxy coated bars.
Remember, for an effective repair job the overlay must be well bonded to the old concrete. This means that its surface must be absolutely clean and free of foreign matter, including particles of epoxy. Carefully clean up any spills or dripping of the epoxy from the rebars onto the old concrete before placing the overlay.