21 Most Frequently Asked Questions About Concrete

If you’ve decided to use concrete for your new driveway, sidewalk, pool deck or patio, congratulations—you’ve made a great choice! Concrete is a durable, versatile, and low-maintenance material that will last a lifetime when properly installed. But if you’re like most people who are new to concrete, you probably have a lot of questions, ranging from “How much concrete do I need to order?” to “How do I maintain my concrete and preserve its appearance?”

Here are the top 21 questions we receive about concrete, along with answers that will help you gain a better understanding of the best practices for concrete installation and care.

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CONCRETE BASICS

What is the difference between cement and concrete?

The words cement and concrete are often used interchangeably. However, portland cement (a type of hydraulic cement made primarily from limestone) is actually an ingredient of concrete, along with sand, aggregate, and water. When these components are combined, a chemical reaction, called hydration, takes place to form a solid material that hardens and gains strength over time. Learn more about the basic components of concrete.

How do I determine the amount of concrete I need?

Because ready-mix concrete is sold by volume measured in cubic yards, you’ll need to multiply the length and width of the slab in feet and divide it by the square-foot coverage based on slab thickness to determine the amount of concrete needed. (Our online concrete calculator can help you do the math.) If you plan to use premixed bags of concrete rather than ordering concrete from a ready-mix supplier, you’ll need to calculate how many bags you need based on the cubic feet of concrete you’re pouring. For more information, see How Many Square Feet Will a Yard of Concrete Cover?

How much does concrete cost per yard?

The cost of concrete generally ranges from $140 to more than $170 per cubic yard, depending on material, labor, and transportation costs. For a more accurate estimate, call your local ready-mix supplier. Learn about other factors affecting the price of concrete.

Can I pour a concrete slab myself?

While pouring your own concrete slab may look like a simple DIY project, it’s not recommended if you don’t know what you’re doing. Even small mistakes in site preparation, concrete mixing, or concrete finishing can cause significant structural problems requiring costly repairs. Here are the most common mistakes DIYers make when pouring a concrete slab.

How long does concrete take to dry?

Under most conditions, freshly placed concrete will dry and become solid enough to walk on 24 hours after placement. However, it will take 28 days for your concrete to fully cure and attain its maximum strength, durability, and wear resistance.

Can you pour concrete in the rain?

After freshly mixed concrete has been placed, exposure to a heavy, driving rain can wash out some of the cement at the concrete surface and compromise its strength. If rain is in the forecast, you should postpone your concrete pour until conditions improve. Learn more: Pouring Concrete In Rain.

Can it be too hot or too cold to place concrete?

Placing concrete during extreme temperatures should be avoided because the concrete may not cure properly. Pouring concrete during hot weather can cause water in the concrete to evaporate too quickly, resulting in a loss of strength. On the flip side, pouring concrete during cold weather can cause hydration to slow to a near standstill and prevent strength development.

How long do I wait before driving on new concrete?

Driving on a concrete slab too soon can cause cracking and other permanent damage. To give the concrete ample time to harden and gain strength, you should wait at least 7 to 10 days after placement before driving and parking a standard vehicle on a new concrete driveway. See How Long to Wait Before Driving on New Concrete.

CONCRETE CLEANING, MAINTENANCE & RESTORATION

Is it necessary to seal concrete?

Periodically sealing your concrete offers a number of benefits. When properly applied, a sealer will help prevent surface defects by protecting your concrete from water absorption, deicing salts, abrasion, and stains. A sealer will also help bring out the natural beauty of your concrete and make it easier to clean.

How do I remove oil and grease stains from concrete?

There are multiple methods you can use to remove oil or grease stains from concrete. Small spills or spots can sometimes be removed with nothing more than a strong detergent and a scrub brush. For more stubborn stains, you may need to use a commercial concrete cleaner and degreaser, a microbial cleaner, or a stain-absorbing poultice.

How do I clean a concrete driveway or patio?

To remove everyday dirt and grime from a concrete driveway or patio, you can usually use a concrete cleaner and degreaser along with a stiff broom or brush to scrub the surface. For more stubborn dirt and stains, a power washer is often more effective, but you need to use the right setting so you don’t etch the concrete. See these tips for power washing concrete.

How do I remove paint from concrete?

The materials and methods required for paint removal from concrete will depend on a number of factors, including the type of paint (water vs. oil-based), the size of the spill, and the porosity of the concrete.

Can you resurface concrete?

Yes, resurfacing is a good way to revive an old, worn, or damaged concrete surface like a driveway, patio or pool deck. It involves applying a thin cement-based overlay on top of the existing slab to cover up any cracks, pits or other imperfections. You can choose different finishes—from simple broom-finished texture to decorative stamped patterns or staining. Properly done, a resurfaced concrete slab can last as long as a new pour but at a much lower cost than full removal and replacement. Just make sure to hire an experienced concrete contractor for professional results.

PREVENTING CRACKS AND OTHER PROBLEMS WITH CONCRETE

How do I prevent cracks in concrete?

If you're having new concrete poured, there are several measures your concrete contractor can take to significantly reduce the possibility of cracking. These include using a concrete mix with a low water-cement ratio, placing the concrete on a well-compacted subgrade, installing control joints where needed, and properly curing the concrete. Learn more about why concrete cracks.

How do I repair cracks in concrete?

Most cracks in concrete can be repaired if you use the right patching materials and application techniques. In some cases, crack repair can be a simple DIY project. In others, you may need to hire a professional to fix the damage. Here are how-to tips for fixing both wide and narrow cracks in concrete.

What causes spalling concrete?

If the surface of your concrete slab is spalling (also known as scaling), it’s often due to poor installation. Common causes include adding too much water to the mix to make it easier to pour, bad finishing techniques, and not curing the concrete properly. Spalling is also more common in colder climates where the concrete is exposed to frequent freeze-thaw cycles. Learn how to prevent and repair spalling concrete.

Can I use salt or chemical deicers on concrete?

Because rock salt and most deicing chemicals increase freeze-thaw cycling, you should avoid using deicers on concrete the first winter after it’s placed. If you do need to apply a deicer, there are several products and methods you can use that won’t damage your concrete or harm your lawn or other plant life. See How to Melt Ice on Concrete.

DECORATIVE FINISH OPTIONS FOR CONCRETE

What decorative finishes can be applied to concrete?

Concrete can be stamped, stained, broom finished, or colored to achieve a wide array of decorative effects. You can also create patterns using stencils and decorative scoring. Take a look at some of your options: 10 Types of Concrete Finishes.

Can I stain concrete myself?

When applying concrete stain, thorough surface prep and the use of the proper tools and techniques are vital to achieving good results. Once the stain is down, the color is permanent and there's no going back. If you have any doubts, hire the services of a professional, especially if you want to incorporate multiple stain colors. See Stain Application: DIY or Hire a Pro?

How long does concrete stain last?

Because stains penetrate into the concrete surface, the color is permanent and won't fade, chip, or flake off like paint. However, the color may eventually wear away as the concrete surface is worn by traffic or weather exposure. To prolong stain life, you should protect stained concrete surfaces with a clear or tinted sealer. Get more tips on how to seal and maintain stained concrete.

What are the benefits of stamped concrete?

Stamping allows you to imprint patterns in a concrete surface that resemble more expensive building materials such as brick, tile, flagstone, and slate. Stamped concrete is also fully customizable by allowing you to combine your choice of colors with many different stamping patterns. Although stamped concrete is more expensive than plain concrete, it can potentially increase the value of your home by enhancing its curb appeal. Learn more about the pros and cons of stamped concrete.

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