Homemade Cement

Concrete

• Concrete usually contains cement, sand, water and rocks of various sizes and shapes. The rocks are collectively called aggregate. Concrete is used in structural components: building foundations and weight-bearing columns in large structures, including massive dams; in foundations and slab floors in smaller buildings and homes; and in smaller projects like paving driveways and securing fencing and mailbox posts. The intended use of the concrete determines what types of aggregate you'll need to include in the mix.

Using Homemade Concrete

• Concrete is a common component for many home projects. While some projects can be done by a single person, those that involve mixing and applying concrete or other cement-based mixtures can be tricky for one person to pull off. If you've never worked with cement, mortar or concrete, you should consider getting help or hiring a contracting company. If the project is small and you want to do it on your own, you'll have more success if you produce your cement mixtures in small batches. You'll need only a few materials and tools depending on whether you are using straight cement, a cement-based mortar or concrete.

Aggregates for Concrete

• Aggregate is all the solid, non-cement ingredients used in the concrete. Aggregates are granular materials that affect the properties of the final concrete product. An aggregate can be coarse, like crushed rock or gravel, or fine like sand. When choosing an aggregate to mix into concrete, it is best to choose aggregates that are durable and strong. Sandstone, for example, is a poor aggregate to mix into concrete. Concrete needs to be durable to harsh elements and weather, so a material like granite would be a better aggregate. You also need to make sure the aggregates you choose do not react chemically with the cement mix.

Proportions of Ingredients

• The general rule of thumb is that for every cubic yard of concrete, you'll need six bags of cement. You'll also need up to 6 gallons of water for every bag of cement used. It is more difficult to determine the amount of aggregate to use. Calculate the total volume of aggregates you need to use by subtracting the cement content from the concrete's wet density. The content of free water is subtracted from the previous number. You can find applications on the Internet that will help you with these calculations, or you can get help from a specialist at your local home improvement store. To make sure your calculations are in the right range, keep in mind the general rule that aggregates should make up 60 percent to 75 percent of a concrete mix.

Mixing the Concrete

• After determining the proportions of the materials you'll need in your concrete, it is time to mix all the components together. First, mix the cement and water and stir well to form a strong paste. The more cement you use, the harder the paste becomes. After stirring these two together, add the aggregates and mix the materials well. As you work, make sure you mix the concrete frequently; the aggregates tend to sink, even in a stiff mixture. Use the concrete immediately after you mix it, because it begins to harden the minute the cement and water come together.