Site-mixed mud can be batched as accurately as ready-mix, given a strong back and a few guidelines.
Synopsis: A short but useful guide to mixing your own concrete. Charts provide the correct proportions of cement, aggregate, and water.
Most batch plants charge extra for less than a cubic yard or two of concrete. The service you’re likely to get on a small order is pretty minimal, so it often makes sense to mix on site. You can do this by hand in a trough or wheelbarrow, or you can rent a mechanical concrete mixer. You’ll be using the same ingredients as the batch plant; if you measure and mix carefully, the quality of the concrete should be at least as good. For folks beyond the range of ready-mix trucks, this is the only way.
Clean water is a must for concrete. Sea water is okay if the concrete won’t be reinforced with steel. The pour will attain high early strength, but will not be as strong in the long run. Increase the cement content and reduce the water to recover some of the strength lost to the salt.
Cement should be bought by the 94-lb. bag and kept dry. In most cases, Type I is what you need. For resistance to freeze-thaw cycles in northern climates, buy air-entrained cement, which requires using a portable power mixer, since the air-entraining agent needs vigorous mechanical agitation to be effective.
Large aggregate and sand can be purchased by the cubic yard from quarries, building-supply yards and batch plants. Large aggregate can range from ½ in. to 1½ in. It should be clean, hard, durable gravel or crushed stone such as granite or hard limestone. Most sandstone isn’t usable. Crushed stone should be square, triangular or rectangular in shape, Flat, elongated pieces shouldn’t be used, Sand, the fine aggregate, should be a mix of coarse and fine…