Concrete questions, answered
Why does concrete crack?
Concrete shrinks as it cures and expands and contracts with temperature, and the ground beneath it can move. Control joints give cracks a planned place to form. Good base preparation, correct thickness, reinforcement and proper curing reduce cracking, but some cracking is normal.
How long before I can drive on a new driveway?
It depends on the mix, the weather and the contractor's recommendations. Walking is usually allowed sooner than driving, and heavy vehicles need longer. Ask your contractor for specific times based on your slab and the conditions.
Should concrete be sealed?
Sealing protects concrete from moisture, stains and, in cold climates, freeze-thaw damage and deicing chemicals. It's especially important for stamped and colored concrete. Reapply as the manufacturer recommends.
Can sunken concrete be lifted instead of replaced?
Often. Slab jacking with a cement-based grout or polyurethane foam injection can lift and stabilize sunken sections. Replacement is better when slabs are badly cracked, crumbling or poorly drained.
What is air-entrained concrete?
Concrete that contains tiny, evenly spaced air bubbles, created by an admixture. The bubbles give freezing water room to expand, which helps concrete resist freeze-thaw damage. It's important in climates with regular freezing.
Do I need a permit for a concrete driveway?
Replacing the part of a driveway in the public right-of-way, such as the approach at the street, usually needs a permit. Other flatwork may or may not, depending on local rules. Ask your contractor.
Is stamped concrete slippery?
Sealed stamped concrete can be slippery when wet. A slip-resistant additive in the sealer and textured patterns help, especially around pools and on walkways.
What's the best time of year to pour concrete?
Moderate temperatures are easiest. Pouring in extreme heat or cold is possible with precautions such as adjusting the mix, timing, covering and curing methods. Ask your contractor how they'll handle the weather on your pour date.
Should I use salt on my concrete in winter?
Deicing salts can damage concrete, especially new, decorative or poorly air-entrained concrete. Sand provides traction without chemical damage. If you must use a deicer, follow the concrete and product manufacturers' guidance.
How do I compare concrete quotes?
Compare excavation depth, base material and thickness, slab thickness, reinforcement, mix, joint layout, finish, curing, sealing, permits, demolition and disposal, and the warranty, not just the price per square foot.
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