Concrete is made by mixing cement with sand, water and aggregates. The cement acts as a dry bonding agent, which when wet adheres to the coarse edges of the sand and aggregate. At times, sand may not be available, leaving the mixer to consider substituting dirt instead. Dirt is generally a rounded material with no sharp edges for the cement to bond to. Although it can be a challenging mix to pull together, it is possible as long as the right materials are used.
Obtain sufficient quantities of the dirt, crushed stone and portland cement. Use only pure portland cement -- not pre-mixed concrete -- when working with dirt. The ideal concentration is one part cement with two parts dirt and three parts crushed stone.
Pour the dry materials into a cement mixer. You can also use a wheel barrow and shovel for mixing, but the work will be messier and more strenuous.
Mix the concrete, dirt and stone with water. Do not add too much water, as this will produce weak concrete. Continue adding small amounts of water while mixing the ingredients until they reach a thick, moist consistency. Measure a sample of the mixture with the slump cone. A slump of 3 to 4 inches is ideal. Anything more and there is too much water; less and there is not enough water.
Continue mixing after you get the correct moisture level until all the materials are well blended. When the dirt can no longer be distinguished from the cement and when the crushed stone is evenly distributed, the mix is ready.
Pour the mix into your concrete forms and spread it evenly. Allow 24 hours for the mixture to dry.
Crushed stone is essential when working with dirt instead of sand. Pebbles also make a nice addition, but they should not be used to replace crushed stone.
Tips and warnings
- Crushed stone is essential when working with dirt instead of sand. Pebbles also make a nice addition, but they should not be used to replace crushed stone.