The Secrets to Pouring Concrete in the Heat of Summer

Longer days and warmer temperatures make summer the prime season for tackling home projects in and out of the house. But those warm, sunny days can be a double-edged sword: All that heat and dryness can create a few challenges for projects that involve pouring concrete, such as planters, garden edging, patios, pathways, slabs, and more.

On a hot day, freshly mixed concrete can start to set in as little as 30 minutes, so you have to work quickly to get the concrete poured and finished before it hardens. As well, concrete that dries out too quickly—a real issue in hot weather—isn’t as resilient as concrete that dries more slowly. Overall, it’s weaker and more likely to crack.

Fear not. You don’t have to wait until fall to pour. Summer’s still a great time to tackle your concrete projects, you just need to borrow a few techniques from the pros. Whether you’re installing an outdoor kitchen, a patio, or just a couple of steps, the following tips from Quikrete‘s team of professionals will help ensure a successful pour and a concrete project that will be the envy of the neighborhood.

As a rule of thumb, 90 degrees Fahrenheit is the cut-off point. If it’s over 90 degrees, plan to pour another day. During summer, pour as early in the morning as possible. This tends to be the coolest part of the day and will therefore offer the best chance for moisture retention as the concrete begins to cure. If pouring in the morning isn’t an option, you can try pouring later in the evening when the temperatures start to drop. Just don’t schedule the pour so late that it gets dark before you finish.

While direct sunlight on wet concrete speeds the evaporation process, high winds can be just as bad—or worse. A windy day can dry out the surface of the concrete before you can smooth it and finish the edges, or create a brushed texture (if you’re pouring a slab). Position sun shades, wind blocks, and anything else you can rig up to keep the sun and wind off the concrete as you pour, then leave the protection in place for a few hours after you finish.

Review your project materials list and make sure everything you need is within reach before you start mixing the concrete. There’s nothing quite like pouring wet concrete into the forms only to discover you’ve forgotten your shovel, trowel, or concrete screed! Once the pouring starts, you’re on the clock—there’s no time to hunt down any tools or supplies you may have forgotten.

Before you start, you also need to make sure you have enough concrete to complete your task. This handy calculator from Quikrete will help ensure that you’ve mixed up enough for your project. Too little concrete, and you risk not being able to fill the entire form in one go. If you have to fill up the rest of the form later, the concrete you initially poured will have already hardened and won’t form a secure bond with the concrete you add, creating a “cold joint,” or a weak spot in the concrete.

If you’re pouring a slab, you probably have a substrate of gravel in the bottom of the forms to help support the slab and reduce movement. Spray the gravel with a hose until it’s saturated, but don’t spray so much that the water puddles. Also spray down the concrete forms to moisten them and cool them off. A dry base can quickly suck the moisture out of wet concrete, making it dry too quickly and ultimately weakening it.

If you have a large pour, such as a patio, wall, or sidewalk, you’ll need plenty of strong arms and backs to
help mix the concrete, spread it in the forms, screed it, and finish the surface. Without enough help, it can be difficult to get the concrete in the forms and smoothed out before it starts to set. To work quickly and efficiently on the day of the project, make sure your helpers all know what their job is before starting. Get ready by checking out this instructional video on how to pour and finish concrete slabs.

Whether you’re mixing concrete by hand according to the instructions in this Quikrete video or you’re using a concrete mixer, make sure your water is cold and always stick to the directions found on the back of the concrete bag.

For best temperature control, use water directly from a garden hose, and let it run a few seconds each time you turn it on until the water runs cold. If you’re pouring concrete in a place where a hose won’t reach, fill a cooler with a bag of ice and add some to your water bucket as needed to keep the water cool.

If you’ve followed the above tips, the pour itself should go off without a hitch! But don’t call it quits just yet. You’ll still need to take steps to prevent moisture from evaporating too quickly. The slower the new concrete project dries out, the stronger it will be.

After smoothing and brooming the concrete surface (if you’re creating a nonslip surface), apply a light mist of water, and reapply it as needed to keep the concrete surface damp. For the next seven days, you’ll want to continue wetting down the concrete several times per day, if possible, but the first couple of days are the most important.

Even easier? You can apply a concrete curing agent, such as Quikrete’s Acrylic Concrete Cure & Seal, to the surface. The sealant forms a membrane on the concrete that keeps moisture from evaporating too quickly.