| Concrete is the most commonly used man made | | | | Pouring concrete, such as a sidewalk, requires |
| building supply on Earth. Six billion cubic meters are | | | | several steps. First, figure out how much you |
| manufactured a year, in a $35 billion industry. This | | | | need. This is determined by measuring the |
| means there are pretty good odds that you'll | | | | surface area and thickness to determine how |
| eventually do something with, or be around | | | | many cubic yards you need, and this will tell you |
| something with concrete. | | | | whether you can mix it yourself, or need to have |
| Weather and climate will affect your concrete. It | | | | it delivered. |
| is not wise to pour your cement in conditions that | | | | Then you build your forms. This probably involves |
| involve a drop below freezing before the cement | | | | digging, and laying 2"x4" boards to hold the edges |
| cures, as this will prevent the cement from | | | | of the concrete. 2"x2" boards should be used to |
| reaching its maximum strength. Likewise, if the | | | | hold those in place, pounding them deep enough |
| humidity is too low, the surface of the cement | | | | that the weight of the concrete won't push the |
| can crack and produce weaknesses for weather | | | | boards out of place. |
| to attack. | | | | You will almost always want to lay reinforcing |
| All concrete will eventually crack to some extent, | | | | material in the bottom, such as metal fencing |
| though this can be minimized by good design and | | | | materials. Ensure that you have everything square |
| selection of good reinforcement where needed. | | | | and at the proper level, as after you pour, it will |
| This does not mean concrete is a bad choice, as | | | | be too late. Then ensure that all of the pieces are |
| concrete structures have lasted thousands of | | | | well secured with nails and clamps. Spray the site |
| years. | | | | with later lightly, and pour. Tamp the concrete |
| Concrete is used as a fire barrier, but while it | | | | down, especially on the edges, and level the |
| doesn't burn, it can be damaged by heat. Once | | | | concrete. |
| the temperature reaches or exceeds 300 | | | | Once it has set enough to support a 2"x8" board, |
| degrees, the concrete is considered unsafe, and | | | | use one as a straight edge to cut contraction |
| this can usually be detected by a pink, light gray | | | | joints. These should be every four to six feet. For |
| or yellow-brown color. Discolored concrete should | | | | sidewalks or narrow areas, this is sufficient, but |
| be replaced. | | | | for patios these should go in both directions. A |
| For handyman style use, bagged cement is | | | | pair of beveled clapboards can be used. Coat |
| perfectly reasonable, and for convenience, there | | | | them with motor oil and place a nail into one. |
| are pre-mixed bags with aggregate already | | | | Insert them into joints on large concrete |
| mixed, just requiring water. These are very | | | | structures. As the concrete begins to set, the nail |
| handy for small jobs such as setting a pole into | | | | is used to remove one of the boards, and the |
| the ground for a doggy chain or clothesline. This is | | | | other is hidden inside, leaving room for the |
| usually too expensive for large jobs. | | | | concrete to expand or contract with the weather. |