EPOXIES VS. POLYURETHANES
Related Links: Why low-pressure injections is best Basic steps in the injection pocess Using epoxies vs. polyurethanes for repairing cracks Tools for crack injection: Advantages of dual-cartridge dispensers Do-it-yourself crack repair: A kit for homeowners Limitations of Low-Pressure Injection How to fix basement walls: Expert tips from Chris Sullivan Concrete Contractors: Find Epoxy and Polyurethane Products and Suppliers So which material is better for repairing concrete cracks: epoxy or polyurethane foam? The answer isn't always clear-cut. In many cases, either material can accomplish the task, and applicators may simply choose the material they have the most experience with. But here are some general guidelines: If the crack needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it, use an epoxy. If the crack needs to be repaired only to prevent water leakage or the crack is actively leaking, a polyurethane is usually the best choice. Here's a look at the advantages and limitations of each material. Epoxies Epoxies for crack injection are available in a range of viscosities, from ultra-thin to paste-like (such as the Emecole Epoxy Crack Repair Products), to accommodate cracks of different widths. Coles advice is to use whatever viscosity is needed to inject a given crack at pressures less than 40 psi. The wider the crack, the thicker the material required. The main advantage of epoxies is their amazing compressive strength, which at 12,000 psi or greater exceeds that of most concrete. That's why epoxies are the only choice for cracks requiring structural repair. However, epoxies cure very slowly, generally taking hours to harden. This can be an advantage because it allows time for the epoxy to flow into even the smallest crevices. On the other hand, its also possible for the epoxy to flow out of the backside of the crack before it has hardened if the backfill outside the wall has separated from the foundation. "Often there are voids behind cracks due to soil erosion or poor compaction," explains Cole. That's why the crack is leaking in the first place; its easy for water to enter. Polyurethanes If there is concern about material leaking out the back of a crack, polyurethane foams (such as Emecole Polyurea) should be used. These elastomeric, fast-setting foams are effective alternatives for applications involving only crack sealing (waterproofing) and not structural repair. Because of their elastomeric nature, they are able to accommodate slight concrete movement so the seal stays intact. They also begin to harden and foam within minutes of injection. This reduces the chances of the material flowing out of an injected crack while still in liquid form, and even if some does leak out, the foam will fill the void. "Urethanes are great for basic crack filling. They add practically zero compressive strength, but in most residential applications, you don't need it," says Cole. See www.emecole.com for more information. Concrete Contractors: Find Epoxy and Polyurethane Products and Suppliers Find a Concrete Contractor 24 Services in 221 Metros -- U.S. and Canada 
| Follow us on:
 
| Sign Up for Our Newsletters:
© 1999-2009 ConcreteNetwork.com None of this site may be reproduced without written permission |
Other Resources |
Concrete Crack Repair
Sign Up Today