Pouring a Concrete Slab CorrectlyPouring a concrete slab is hard work, but the steps involved are relatively simple. With the right tools, good planning, and a willingness to do some fairly heavy physical work, you can pour your own DIY slab of concrete for a sidewalk, patio, or other use. I'm going to take you through the steps of framing, mixing, and pouring a simple rectangular slab. If this is your first concrete pouring experience, you are advised to start small. If you take on something large, like a parking pad for your driveway, you might be easily overwhelmed by the experience. A small pad for your barbecue grill, or a stepping stone, on the other hand, might be a good first project. This project assumes you will only need an amount of concrete that can be mixed in a standard wheelbarrow. Tools & Materials Needed concrete mix circular or table saw The first step is to dig a space for pouring a concrete slab.It should be bigger than the actual slab because you'll set your lumber frame in the space before pouring.After you have the space dug, use your level to make sure the ground is flat. It is important that the ground where you're pouring is level so that the concrete will set properly. Next, cut the lumber to the correct size and create a frame for the concrete slab.The inside area of the frame should have the same area as the concrete slab you want to make.If your frame is larger than 4 feet in any dimension, you may need to add a diagonal cross brace to strengthen it. Set the frame in the ground where you want to pour your concrete slab. Make sure the area inside the frame is level and that any debris like grass is cleared from the inside of your frame. Now it's time to mix the concrete.You'll basically follow the directions on the package of concrete that you have, mixing it in your wheelbarrow.Measure the water carefully. The curing process will depend on having the correct ratio of water to other materials. Using your shovel or a garden hoe, stir the concrete until it is mixed thoroughly and is of the right consistency. Mix in sand or gravel if the directions on the package say to. Measure these properly, too. Make sure the water you use is clean and is not contaminated with any sulfates, oils, alkalies, or acids. Just as a rough guideline, for retaining walls and foundations, use 6.25 gallons of water for each sack of concrete if the sand is damp. If the sand is wet, only use 5.5 gallons of water. For sidewalks and stepping stones, the mix should consist of 5.75 gallons of water per sack of dry mix for damp sand, or 5 gallons if the sand is wet. In some cases, such as sidewalks, concrete should be reinforced with steel mesh. This can be regular fence material or a grid of rebar or other steel. This grid should usually be laid deep in the bottom of the slab. On the other hand, if the strong point of the slab is in the middle and pressure will come from either end, the reinforcement mesh should go high up and closer to the top of the slab. Before pouring or shoveling the concrete in to the frame, lightly spray the ground and the inside of the frame with water. When the form is full, use a tamper to ensure that the poured concrete is compacted around the edges. A stepping stone can be easily compacted using a 2 x 4. Larger areas may require a roller tamper. Once it's tamped, use a 2 x 4 as a screed to level the concrete. Use your finishing trowel to smooth the surface. Add contraction joints to control and minimize cracking.Add the contraction joints when the concrete has set well enough to support a 2 x 8 plank.Use the 2 x 8 as a straight edge to guide a groover (which can be a nail hammered into the side of another 2 x 8) to slice contraction joints in slabs measuring larger than 4 feet in any dimension. Contraction joints help keep concrete from randomly cracking. Contraction joints should be at least one-fourth the depth of the slab. Let it be... Let it cure.Allow the concrete to cure for several days after pouring a concrete slab. During this time, keep the concrete surface wet by misting it twice daily and covering it with a tarp.This sets up the chemical reaction that gives concrete its strength. Well, that about covers it. If you have any questions on how to pour a concrete slab, please feel free to ask me. Return to DIY Project Advice
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