How to Pour Concrete
All homeowners should have a very thorough understanding of concrete in order to save not only time but also effort and money. You will achieve a better result for projects that involve determining which type of concrete to use, mixing, estimating materials, building frames, pouring, reinforcing, styling, and curing. Read these tips and instructions before starting any concrete project.
Which Concrete to Use
Although a wide array of concrete is available for sale, ready-mix concrete is a popular choice because of its simplicity. All it needs is water. Although it is convenient for small areas, it is too expensive to use for large projects.
Revolving barrel trucks supply transit-mix concrete, which is great for large projects, but you have to plan for the cost of delivery and mixing. Shop around for the best price. Services are sometimes available which allow you to rent a mixer truck so you can enjoy the convenience of delivered concrete without the full expense.
To save the most money, buy the dry ingredients and mix them yourself. It's arduous labor, and you need to have the appropriate mixing tools.
Mixing Your Own Concrete
There are four basic elements in concrete: Portland cement, a fine aggregate, such as sand, a coarse aggregate, such as crushed rock or gravel, and water. Sand and gravel comprise the majority of finished concrete, but you should always make sure the components are free of dirt and other debris. The best water to use is filtered water that is acid-free, alkalide-free, oil-free, and sulfate-free. Concrete components never change, but the quality of the end result always depends on how well you mix them.
When you are working with moist sand, add 6 1/4 gallons of water for each standard bag of cement to build concrete foundation walls and retaining walls. Adjust the amount of water according to the dampness of the sand. To mix concrete for a sidewalk, begin with wet sand and add 5 3/4 gallons of water for each bag of cement. If you are working in a very small area, measure the components according to the outlined ratios. Always adhere to the manufacturer's instructions for mixing the concrete.
Estimating Your Materials
Refer to this chart for information on the number of cubic yards of concrete required to pour slabs.
|Area in square feet
(length x width)
|Thickness in inches|
Determine the total square footage of your project by multiplying the length of the work area by its width. Then, compare the square footage by the thickness of the planned slab.
Building the Forms for Pouring Concrete
In most cases, you will have to build a frame for the concrete, either by digging or constructing-up.
Excavate as needed and construct a frame with 2x4s to accommodate the design of your concrete, whether it be a patio, path, or what have you. Design the slope with temporary posts. Then, use nails to attach stakes to the forms which you have built. If you prefer, you can also make use of clamps to hold the forms in place. Use a level to verify that you have the proper grade for your slope. Once you’ve confirm that it’s correct, place permanent stakes to fasten the form.
Concrete is best poured when temperatures are between 40 to 80 degrees Fahrenheit. Hot weather and direct sunlight can make your concrete cure too quickly, which will cause it to crack, and cold air will prevent the concrete from setting at all. Look for a string of days boasting moderate temperatures and try to schedule your pouring then.
Wet the area for the concrete with a hose and then pour it. The concrete must completely fill the entire area you’re pouring. A 2x4 can be used to tamper small spaces, but when working on a large space, you should use roller tampers.
Flatten the concrete and create clean edges by scraping a wooden board along the top of the form. This process is called screeding. You’ll want to sweep the board over the surface several times to get a good, level surface. A concrete rake can come in handy for leveling areas which cannot be reached with the board.
Once the concrete has partially hardened, sweep a grooving tool over it to cut. Concrete contracts during the cool season and expands in the warm season, so you must cut contraction grooves in the surface to prevent cracks. Narrow patches of concrete require grooves every four feet, while large concrete patches require grooves to be cut in each
direction. Form grooves for large concrete patches by implementing two pieces of beveled clapboard as illustrated.
Apply motor oil to the beveled clapboard after driving a single nail into one. Insert the boards into the concrete, and then pull the board with the nail free when the concrete has partially settled.
To make the strongest concrete for your project, you should reinforce the material with mesh or chain link fence. Adjust the placement of the mesh according to the area where pressure will be the strongest. Mesh should be placed lower for concrete patches that will receive pressure from the center. If pressure will be applied from the sides, install the mesh toward the top.
Ways to Finish Concrete
Smooth the concrete with a trowel. To add a decorative touch, sweep the trowel in a circular motion for a swirled pattern. For a more pronounced pattern, sweep the concrete with a wood float, or form a lined pattern simply by sweeping the concrete with a broom. You can even make wavy lines with a garage floor brush, which slip-proofs the floor, or make a flagstone look with a bent copper pipe. A mold can also create a flagstone pattern, but you will probably have to hire a contractor to stamp the concrete for you. However you choose to finish it, make sure water doesn't lodge in the grooves, as it will deteriorate the concrete faster.
Finally, you can add dye to the concrete to change the color to whatever you choose.
Curing the Concrete
Mist the concrete with a garden hose to keep the top moist while it settles every 12 hours for three days. Cover exterior concrete with either building paper or burlap between misting. Interior concrete doesn't need to be misted, but you must make sure nothing disturbs it while it cures
Once the project is complete, you should seal it. You may select a sealant that provides texture and eliminates slips, but definitely avoid sealants that become slippery when wet for exterior projects.
Information in this article has been furnished by the National Retail Hardware Association (NRHA) and associated contributors.