Many outdoor home-improvement projects involve concrete. Before you start them, you need to know which kind of concrete is best for each application. Standard concrete mix (figure A), consisting of equal parts Portland cement, gravel and sand, works well for most applications such as patio slabs and walkways. Fast-setting concrete mix (figure B) is good for fenceposts or mailbox posts. It sets quickly because it includes fast-setting additives. Fiber-reinforced concrete mix (figure C) is used primarily in cosmetic areas. It works well for covering cracks in existing concrete. Commercial fiber-reinforced concrete has a high compression strength, which means that it can't be easily compressed. This kind of concrete sets quickly and can usually withstand pressures of up to 5000 pounds per square inch. When you work with concrete, you'll need certain tools. One of the most important is the finishing float. Different styles are available, including floats made of wood, steel and magnesium (figure D). Choose one that fits your personal preference. For most applications, wooden floats are perfectly fine for homeowner use. When mixing concrete, wear a dust mask. Mix the concrete in a large container such as a wheelbarrow, using a hoe or a "potato masher" concrete mixer. To prevent the concrete from getting too wet, pour the water first, then mix in dry concrete until you reach a consistency similar to that of oatmeal (figure E). If you're installking a walkway, you'll need forms to shape the concrete. When using forms, make sure they're level, and smooth the concrete with a small trowel to prevent air bubbles from forming (figure F). For most applications the concrete should be at least 4" to 6" thick. The ideal temperature for concrete installation is 40 to 50 degrees Fahrenheit. If the outside temperature is colder, use warm water to mix your concrete; in warmer temperatures, mix the concrete with cold water. After pouring your concrete, use a float to press the gravel down to the bottom and bring the cement to the top for a smoother finish (figure G).
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