Concrete Repair: Bonding Agents

Bonding agents are a widely debated family of products. Some concrete contractors will tell you they have a favorite bonding agent, one that they use almost exclusively. Others say they evaluate every job and develop a unique solution, drawing from a wide range of products. And there are some contractors who swear by the oldest bonding agent of them all, simply using a mixture of portland cement and water. In fact, there are dozens of products and methods that may be used to create a bond between old concrete and new.

If there's one thing that nearly all contractors agree on, it's this: no matter what bonding agent is used, proper preparation of the substrate is essential for a successful, lasting bond. "Regardless of the manufacturer, polymer-modified toppings are only as good as the substrate on which they are installed," says Scott Truax, president of the Concrete Division of Vail, Colo.-based Gallegos Corp.

Bonding agents fall into two basic categories, cement-based bonding agents (which include simple solutions like a slush coat or a scrub coat as well as a wide variety of latex-modified bonding agents), and epoxy bonding agents.

And new products are being introduced all the time. "New bonding agents today allow you to apply it and let it get to a hard state, where you can walk on it while it's tacky," says Bob Ware, owner of the Decorative Concrete Store in Cincinnati. This allows the contractor to do larger areas at a time, he says, saving time and costs on big jobs.

Other manufacturers are adding tint to bonding agents so contractors can ensure even and complete coverage. The bottom line: contractors have to find the methods that work for their unique jobs to ensure a complete, lasting bond.