When mixing concrete for a specific project there are a few things you should keep in mind. First, it is important to know what soil type you plan to pour your concrete into. Different soils such as sand or clay offer very different load bearing qualities for your finished structure. Because of this, the type of aggregate used in the mixture needed for your project will vary.
It is equally as important to correct and issues your soil may have in regards to how compact or loose it is before pouring concrete. In some areas, it is recommended to have a survey soil taken in order to best deal with any issues the soil type may pose. These surveys are used to check soil type and density that will ultimately tell you how to properly prepare the ground before your concrete pour. Failure to do so can result in cracks forming in the concrete as the ground settles.
The other important aspect of concrete mixtures is determining how strong the structure needs to be. For instance some people consider a typical mortar mix to be concrete and just as strong as any other concrete. This is not true. Where a mortar based type of material contains cement and water like concrete, the aggregate used in mortar is usually nothing more than a fine grade of sand.
This will work fine for joining two blocks or bricks, but has virtually no real strength properties. Aside of the fact that you’ll have to run some sort of steel wire mesh and/or rebar in the concrete, the aggregate choice you make will determine a lot of the strength properties of the finished product.
It can be said that one of the real strengths of a good concrete mixture is the size of the aggregate in the mix.
As an example, a nice 4 inch slab of concrete might utilize 3/4 inch rock as an aggregate. The binders in the cement and sand will hold the rocks tightly together to form a stronger stone like substance. Because of this, the rock size will definitely ensure more strength, but that does not mean if you poured the concrete mixture out at 3/4 of an inch thick, that 3/4 inch aggregate would be suitable.
You have to make sure that the thickness of the concrete mixture being poured is enough to properly encapsulate the stone aggregate. Otherwise, you’d end up with a thin layer of concrete that consists of nothing more than cement followed by a rock, followed by cement which would not be very strong at all.
There are also a variety of admixtures that can be blended into the concrete mix. Some of these will assist in either accelerating or retarding the curing process. Others like fibers, will add to the sheer strength of the finished product. Of course there are also
- Corrosion inhibitors
- Bonding agents
- Pumping aids
These are all designed to improve both the way the concrete is applied and used. Fiber reinforced concrete is made by adding fibers that are typically made of steel, glass, synthetic or natural processes. Each of which will add a certain amount of strength to the concrete after it has cured.
It is always recommended that you consult your local concrete manufacturer and discuss your soil type and the needs of your project. They usually have several formulas on hand to choose from that should suit your needs.