Concrete Driveways, Sidewalks & Patios Educational Content
DRIVEWAYS
Residential concrete driveways should be at least four inches thick. If they’re much thinner, they will be more likely to crack over time. The driveway should also have adequate slope and drainage. This prevents water from puddling or running down the side of the driveway. A concrete surface that doesn’t drain well is at higher risk of erosion and cracking.
The first step in replacing a concrete driveway is to break up and remove the old driveway. Then, the contractor may put down extra gravel or fill to create a stronger base. This base material should be compacted with mechanical tamping equipment. This step helps ensure that the new driveway will be poured on solid, dense ground. A dense, well-prepared base won’t be as susceptible to erosion as it might be otherwise. The contractor might also add a steel reinforcement grid for additional strength. With temporary forms in place, the contractor will pour and smooth the concrete. Then, the crew will cut shallow grooves called control joints into the slab. The forms are removed once the concrete hardens.
The concrete curing process begins as soon as the concrete is poured and smoothed. Along with control joints, the curing process is vital to preventing the slab from shrinking and cracking.
You’ll be able to walk on the driveway a day or two after pouring. After about one week of curing, you will be able to use the driveway for light vehicle traffic. After about one month, the driveway will be completely cured and ready for full use. Keep an eye on your driveway for the first several weeks after it’s poured. As concrete sets, it has a natural tendency to shrink. This shrinking can cause cracks, especially in large projects like driveways. Control joints (and a proper curing process) allow the concrete to contract while minimizing cracks in the surface.
Superficial cracks are virtually inevitable. So many things can cause them, from the weather to small changes in the soil. Because of these variables, companies can’t guarantee their concrete projects against superficial cracking. Fortunately, these cracks don’t affect the concrete’s strength. Larger cracks, however, may be worth a second look from your contractor. In rare cases, large cracks can compromise the driveway’s strength. If this happens, the slab may need to be torn out and replaced.
PATIOS AND WALKWAYS
There are a few common methods for using brick, stone, or pavers on a patio or walkway. The first uses mortar to attach bricks or stone to a poured concrete surface.
The second method involves placing bricks or pavers onto a prepared sand bed. This method doesn’t involve mortar. It makes for a relatively quick update to your outdoor living space. It also doesn’t need much ongoing maintenance. With the variety of paver and brick styles on the market, you can customize the surface to your liking.
Your contractor should first tamp down the sand or crushed gravel base. The finished surface should be compacted again (lightly, this time). This final step ensures that the pavers are solidly in place and won’t move around. These steps are important for safety and the long-term appearance of the patio or walkway.
Some contractors attempt a third method: placing the bricks or stone on a sand bed and then mortaring between them. Walkways made this way usually don’t age well. Materials sitting on sand move around with normal use, which could break up mortar joints. If you want mortar joints in your patio, insist on a concrete foundation.
PAVERS
Pavers are brick-like pieces of high-density concrete. They come in different sizes, shapes, and colors. They can even mimic the look of cobblestone, brick, and slate. Concrete pavers are usually more expensive than standard concrete but less expensive than brick or natural stone. Pavers are installed individually as the top surface of a patio, walkway, or driveway. In most cases, pavers aren’t mortared in place.
If you opt for a paver surface, the contractor will start by excavating the space. Once that step is complete, the dirt will be compacted with a compaction machine. Next, the crew will put down layers of crushed stone as a foundation for the pavers. After the final layer of crushed stone is in place, the crew will put down and compact a layer of granite sand. This fills the gaps between the crushed stone and creates a smooth surface for the pavers.
Then, the team will install the pavers in whatever design you choose. After the pavers are laid, they are tapped firmly into place with the compaction machine. Next, the installers spread a layer of polymeric sand or regular sand on top of the pavers and sweep it into the cracks between them. Polymeric sand binds together when it is sprayed with water. This makes the pavers more secure.
CONCRETE CURING
The concrete curing process is one of the most important steps in a concrete job. Concrete that isn’t cured the right way can be as much as 50 percent weaker than properly cured concrete. That’s a significant difference. And while the curing process may seem like a lengthy end to a time-consuming project, the results are well worth it. Properly cured concrete surfaces are strong and less likely to crack. They also wear better and more evenly over the years.
The most common concrete curing methods are water curing, surface sealing, and chemical curing. The goal of all three methods is to prevent water from evaporating from the concrete as it cures. Concrete that is water cured is kept wet during the curing process. The contractor will do this by flooding the concrete, continuously spraying it with water, or covering it with cloth that is kept wet.
Concrete surfaces can also be covered (or sealed) to keep them wet during the curing process. For this method, the contractor covers the wet concrete with heavy paper or plastic film. This cannot be done until the concrete has hardened enough that the material won’t mar the surface. In most cases, this is one to two days after pouring.
Chemical curing involves spraying the finished concrete surface with a chemical that forms a thin membrane. This chemical membrane prevents the water in the concrete mix from evaporating.
HOW CLIMATE INFLUENCES INSTALLATION
Concrete installation can vary based on different soil types. In areas with expansive soil, concrete contractors use a thicker gravel base. A thick gravel base compensates for the expansive soil that shrinks and expands with changing moisture levels.
In areas with very dry soil, concrete crews dampen the soil before pouring any concrete. This prevents the soil from leaching water from the wet concrete and making it brittle.