How to Pour a Concrete Sidewalk (page 3 of 4)

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Advice and Safety Tips

Steel Mesh And Expansion Strip Prevent Heaving, Cracking And Buckling
Mesh comes in 5-ft. wide, 25- or 50-ft. long rolls. Some lumberyards also carry 5 x 8-ft. flat sheets of mesh that are easier to handle but cost more per square foot. If a roll is a little too short for the job, finish up the rest with these sheets rather than buying a second roll.

Expansion strips are asphalt-impregnated fiber strips that compress when concrete expands to prevent heaving, cracking and buckling. Pick up 4-ft. expansion strips for each 30 ft. of sidewalk and for ends where the sidewalk abuts other unyielding masonry surfaces such as driveways, other sidewalks, house foundations and steps.

Watch The Weather Channel; Dry, Cool Weather Is The Best For Pouring
The quickest route to disaster is an unexpected rainstorm, either in the middle of your pour or during the finishing process. If there’s a chance of rain on the pour day, cancel the order and set it up for a different day. During normal summer weather (60 to 80 degrees F), you’ll need three to five hours to pour and finish. Don’t order concrete for delivery too late in the day or you’ll be finishing in the dark. To ensure a strong sidewalk, avoid very hot days and days that are followed by freezing nights.

Have At Least Three Helpers Ready To Haul And Level The Concrete
Screed (level the concrete even with the top of the forms) every few feet of pouring. With three people, have one person screeding and directing wheelbarrow dumps while the other two haul concrete to keep the project moving along. The person who’s screeding can usually also go back and do large sections of bull floating over freshly screeded areas.

Use the bull float right after screeding if there’s no bleed water present. Bleed water is water that migrates to the surface from the fresh concrete in small pools. Look carefully; bleed water can be hard to spot. Don’t work concrete with bleed water present; wait until it reabsorbs or evaporates. It’ll seriously weaken the surface, which may flake off later. Wait until it disappears before using the bull float or hand float.

Working With Concrete Safely
Concrete is a fabulous, inexpensive paving material. But as any emergency room doctor can attest, its benign appearance belies a caustic, highly alkaline nature. Wet concrete on skin can cause everything from mild redness to third-degree, permanently disfiguring chemical burns. A few drops of concrete isn’t dangerous, but avoid practices like working in concrete-sodden clothes, concrete-filled boots or gloves wet with concrete juice. It’ll keep you out of the hospital waiting for skin grafts. Take these steps to protect you and your helpers.

Wear eye protection. Sandy concrete splashes can wreak havoc with your eyes.
Wear long pants and long sleeves to protect your skin. (We didn’t only because it was very warm and humid. But we did rinse off any skin that got splashed.)
Wear tall rubber boots if you have to wade in wet concrete.
Wear gloves (rubber gloves are the safest bet).
If your clothes get saturated with wet cement, remove them, thoroughly rinse your skin and change into clean clothes before going back to work.

Here’s What You Need To Know To Shape And Smooth Fresh Concrete
Start hand tooling (floating, edging and grooving) when you can’t push your thumb into the surface more than 1/4 in.

The series of step-by-step photos may give the impression that each tool is used only once for a specific task. While that’s true of the bull float and broom, you’ll need to switch between the hand tools throughout the finishing process as the concrete firms up. Use the mag (magnesium hand float) to resmooth areas and to work out holes as they appear. You’ll also use it to soften transitions between edges, corners and control joints after they’re cut in, and to smooth ridges you produce with the groover and edger (“Two Heavy Wheelbarrows Can Save the Day”). The first time is easy; light pressure will even out the surface. As the mud continues to set up, you’ll have to work harder and harder to smooth out imperfections. Toward the end, you’ll have to put both hands on the mag’s handle and scrub to smooth problem areas.

Make the first pass with the edger and groover when the concrete is just beginning to firm up to form the rough shape. Use them to push the aggregate (gravel in the concrete mix) away from the rounded edges. The next pass gives a more finished shape as the concrete begins to harden. One last time polishes the final shape and smooths out inconsistencies.

Always work the concrete from where you poured first. Avoid overworking the concrete. Your goal is to create a flat, ridge-free surface for the broom finish. If you tool the surface too much, you’ll weaken it.

TIP
If the concrete “gets away from you” (sets up faster than you can finish it), just concentrate on getting the hand floating, edging and brooming done and forget the control joints for now. You can always rent a diamond masonry saw and cut in the 1-in. deep control joints another day. Focus first on getting a good-looking surface.