Concrete Mix Ratio

Scholasticus K Oct 9, 2018
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Concrete is a predominant component among all construction materials. Today, the enhancement in civil engineering and construction technology enables us to use a concrete mix ratio that suits the purpose of all structures individually.
Cement is a fine powder made up of aluminosilicate and calcined limestone, along with a low volume of calcium sulfate and clay. Cement is like a binder or adhesive. When mixed with water, and exposed to air, it acts like a gluing agent. It is also called Portland cement or Ordinary Portland Cement (OPC).
Concrete is made up of Portland cement, water, sand, and gravel (both of which are known to be aggregates), plus some additional chemical if the need arises. 
Mortar is a mixture of aggregate, binder or adhesive, and water, that solidifies when it dries, and fuses particles or surfaces. Hence, concrete is a kind of mortar, also referred to as cement concrete.
The ratio of the concrete mixture, of course, matters a lot. There are several permutations and combinations of the concrete mix by weight, quality of cement and aggregates, and even the nature of ingredients, which ultimately define the nature of the solidified concrete.
The nature of these qualities defines the strength, durability, and even the tensile strength of this building material. The right ratio, thus, gets you the best solidified concrete.

Different Ratios in Use

The normal ratio of concrete mixture is:
☛ 6% air
☛ 11% Portland cement
☛ 41% gravel
☛ 26% sand
☛ 16% water
When you need exact volumes by the dimensions which you want to fill up, then you will have to use a ratio calculator. Today, there are two frequently used ratios of concrete mix:
☛ 1:3:6
☛ 1:1:2
These imply the ratio between, cement, aggregate, and water. 
In the presence of water, the cement reacts, and spreads itself over all the particles of aggregates, physically fusing them together. Thus, better concentration of cement means better concrete, and lesser concentration means lesser strength. For more strength, there are several types of concrete mixtures are used at the industrial and non industrial level.
The ratio of components will differ as per the purpose of initially mixing the concrete.
  • The 1:3:6 ratio concrete is applied if you are planning to build a porch or sidewalk along the house. The mix ratio for building a patio, with a small amount of masonry and bricks, will also be the same.
  • However, if you are building a wall, pillar, or a building foundation, then, along with the reinforcement (RCC), you will also require the 1:1:2 ratio concrete. In cases where the structure has to bear a substantial weight, and is exposed to gravitational force, this mix ratio plus RCC is utilized.

How to Mix Concrete

Mixing concrete in the right proportion is not that difficult. All you will need is:
☛ cement
☛ good quality gravel
☛ sand
☛ proportional water
☛ a wheelbarrow
☛ a regular shovel
☛ safety gloves
☛ protective gum boots
☛ an apron (as cement is not skin-friendly, and it tends to damage sensitive skin)

Here's how you can go about it:

1. The first step is very important. Determine the purpose and volume of the concrete that you will be needing. To know the volume, you will need an online calculator which will provide you with a certain ratio, weight, and volumes of the four ingredients. Note that getting the right weight is going to affect the strength of the concrete. Hence, be careful.
2. The second step is to get the raw material. In cases where you will be needing huge amounts of concrete, try ordering it from a ready mix supplier. He will be able to provide it through a mixer trailer.
3. The process you will need to mix cement manually, is fairly simple. Start off by filling half the prescribed water proportion in the wheel barrow.
4. Add half the gravel, half the sand, and half the measure of the cement.
5. Mix it up a little with the shovel, and in the same sequence, add the remaining ingredients.
6. Keep mixing with the shovel till the mixture becomes uniform and even. This will take a very long time and hard effort, but once done, you can apply the concrete.
Note the solidification timing of the mixture, and work accordingly. In cases where the quantity of the concrete is a bit large, you will need to make sure that you work fast. Otherwise, it would be better to prepare the mix in batches. In case you are doing so for any structure, or for home construction, consult an engineer or an architect for the task.