Spalled Concrete in a New Driveway
I had a new driveway installed last fall, and the following spring the surface began to flake away in some areas. The driveway isn't even a year old. Why is this happening?
Premature concrete surface failure, or "spalling," is caused by the expansion and contraction of water within the concrete as it goes through freeze-thaw cycles. Good-quality concrete that was mixed, placed and finished properly should be able to handle typical freeze-thaw cycles for decades without issue. But if your concrete contractor left out the air-entraining admixture (see Protect Against Freeze-Thaw Cycles), added too much water or overfinished the concrete, you now have concrete that is weak and susceptible to freeze-thaw destruction. Such surface failures often occur after the first or second winter or after a very bad winter with conditions that are colder and wetter than average. Deicing chemicals can magnify the problem and cause additional water saturation of the concrete. Use deicing salts that are labeled as "concrete friendly," and wash salt residue, including that dripping from your car, off the concrete as soon as temperatures and conditions allow. (See How to Maintain Your Concrete Driveway.)
VIDEO: UNDERSTANDING SPALLED CONCRETE
Watch this easy-to-understand explanation of what causes concrete spalling, from concrete expert Chris Sullivan. – Length: 06:08
VIDEO: REPAIR SPALLED CONCRETE
Watch this easy-to-understand explanation on repairing spalled concrete, from concrete expert Chris Sullivan. – Length: 05:17
Sealers are a great way to protect concrete from spalling deterioration. A good-quality sealer designed for use on exterior concrete will help minimize water saturation and protect against salt damage. Even with a good sealer, the concrete itself remains the most important component in avoiding spalling (see The Correct Concrete Driveway Mix). In most cases, spalled concrete is caused by poor finishing and the use of water on the surface to aid in the finishing process. Excess water and overfinishing create a weak surface that can't handle freeze-thaw expansion and contraction. You should always get a signed contract with a concrete installer with specific warranty language dealing with spalling and cracking. To fix the spalling, you may need to resurface the driveway with an overlay (see How to Fix Spalled Concrete).
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Author Chris Sullivan, ConcreteNetwork.com technical expert and vice president of sales and marketing for ChemSystems Inc.