How to Finish a Concrete Surface
Concrete is a mixture of Portland cement, gravel, sand and water. It is used in a variety of building projects and is often used for building foundations and sidewalks. You need to build a form to contain your concrete before pouring it. To finish concrete properly, you need a very specific set of tools as well as some time to learn to master the proper finishing techniques. Every step of the finishing process requires a different finishing tool. Some you may want to purchase to keep, others you should rent unless you'll be doing a lot of concrete projects. If you're a novice, it's best to practice on a small project to begin with. Once you have perfected your concrete finishing skills, you can move on to a larger project. Does this Spark an idea?
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Things You'll Need
- Poured concrete in a form
- Magnesium float
- Edging tool
- Grooving tool
- Steel trowel
- Darby
- Screed board
- Plywood boards 1 x 2 inches wide and the width of your project
- Rubber work gloves
- Safety goggles
- Rubber boots
- Broom
Instructions
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1
Gather your concrete finishing tools together so that you'll be ready to finish the concrete surface immediately after the concrete is poured.
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2
Pull a screed board across the surface of the wet concrete in a back and forth motion. The object of the screeding is to level the surface of the concrete to make it even with the forms. If you see a low spot, smooth the concrete into it to level the surface.
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Move the darby across the surface of the concrete in an arc (semi circle) design, overlapping each arc as you go. Flatten the surface and fill any small holes left by the screeding as you sweep the darby; lift the leading edge very slightly. Continue this process one more time but not more. You don't want to overwork the concrete.
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4
Wait while the concrete begins to set. Water will rise to the surface and disappear. Test to see if the concrete is ready for the next step by pressing a gloved thumb onto the surface near the edge of the concrete. It will be ready to work on again when you can press in only ¼ of an inch.
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5
Move the edging tool back and forth over the surface. Lift the front edge as you smooth and round the edges of the concrete. Run the edger around the perimeter to round out the corners.
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6
Divide the concrete slab into equal parts using a straightedge such as a plywood board and a grooving tool. For a path or sidewalk you should place a groove every 4 feet. For a driveway, do this every 10 to 12 feet. This will keep the concrete from cracking. Set a plywood board into the concrete at each of these distances according to what you are constructing. Run the grooving tool back and forth along the board until the bed of the tool is flush with the surface of the concrete.
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7
Run a magnesium float over the concrete surface in large semi-circles to compact the concrete. Be sure to lift the front edge slightly as you do this.
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Smooth out any streaks left by the edging or grooving tools with a steel trowel. Hold the trowel flush against the surface and move it in large overlapping semi-circles. Apply pressure while doing this.
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9
Sweep a broom over the surface of the concrete to make a textured, non-slip surface.
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Tips & Warnings
Keep in mind that the larger the slab, the more difficult it will be to finish the concrete before it sets. Concrete will set faster in hot, dry weather. It will set more slowly on a cool day or in the shade.
Wear rubber gloves, long sleeves and pants, safety glasses and rubber work boots. Concrete can burn your skin. If you get wet concrete on your skin, rinse it off with water immediately.
