6 / 10
Avoid Too Much Water in the Concrete Mix
When you have concrete delivered, the first words out of the driver’s mouth may be “Should I add some water?” Unless the concrete is too dry to flow down the chute, your answer should be no. The right amount of water is carefully measured at the plant. Extra water weakens the mix. More water makes it easier to work with right away, but will lead to a weaker slab.
If you’re mixing concrete yourself, do this test: Plow a groove in a mound of concrete with a shovel or hoe. The groove should be fairly smooth and hold its shape. If it’s rough and chunky, add a smidgen of water. If it caves in, add more dry concrete.
7 / 10
Don’t Delay Floating the Concrete
After screeding concrete, the next step is to “float” it. Floating forces the stones in the mix down and pulls the cement “cream” to the surface so you can trowel or broom the surface later without snagging chunks of gravel. If you wait too long and the concrete begins to stiffen, drawing the cream up is difficult or impossible. So the time to float is right after screeding.
On a long sidewalk or driveway, it’s best to have a helper who can start floating even before all the screeding is done. There is one reason to delay floating, though: If puddles of water form on the surface after screeding, wait for them to disappear before floating.
On small projects, you can use a hand float made from wood or magnesium. The “mag” float glides easier for less arm strain. But for bigger projects like driveways or patios, don’t mess around with a hand float. Instead, use a bull float. The long handle extends your reach and makes the job easier, while the broad head covers the surface quickly and flattens out any bulges or depressions. To make the surface as flat as possible, float it in both directions. Learn how to pour concrete patio.
8 / 10
Cut Deep Control Joints in the Concrete Walkway
The grooves in concrete are called “control joints” because they control cracks in the surface. Concrete shrinks as it dries, so cracks have to happen somewhere. Control joints create straight breaks rather than an ugly spiderweb pattern. They also limit cracks that form later. On a sidewalk, space joints 5 ft. apart or less; on a slab or driveway, no more than 10 ft. apart.
There are two ways to make control joints: Plow them in the wet concrete right after floating or cut them the following day with a saw. You can buy a diamond blade for your circular saw at home centers. Creating joints with a “groover” in wet concrete is less work and less mess. Joints should be at least one-fourth the depth of the concrete.
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