Definition and process of volume batching

What is volume batching of concrete? - Batching of concrete involves calculating various elements of concrete (i.e. cement, sand, coarse aggregate and water) prior to mixing it.

If this calculation is accomplished based on the volume, it is known as Volume Batching. Prior to apply volume batching method in construction site, the following points should be taken into consideration.

1. Volume batching is not treated as a perfect method for working out the concrete materials.
2. It is not suitable for reinforced concrete structure.
3. This method of concrete batching is not inexpensive.
4. It can only be applied for insignificant concrete or for small concrete works.

How volume batching is performed in job site?

Prior to batching concrete elements in respect of volume, the following points should be considered.

1. What is the relevant ratio of concrete elements with regard to volume?
2. What is the water-cement ratio?

Once the above things are cleared, one can go with the batch concrete elements in jobsite.

In this article, a table is given to get the related proportion of various elements for various grades of concrete. The water-cement ratio should be applied according to the contract.

STEP-1-Batching of cement: The measurement of Cement is done with weight. Frequently, it is utilized in terms of bags. The weight of one bag of cement is 50 kg and it contains a volume of 35 litres (or, 0.035m3).

Cement should never be batched with volume since its weight per unit volume fluctuates in accordance with the way the container is filled.

STEP-2-Batching of aggregate (by volume)

For batching of fine and coarse aggregate with volume, a gauge box is recommended. The box should not be very shallow. It must be entirely stuffed with aggregates. The top of the materials should have been struck off level through a straight edge. The capability of the box is dependent on the proportion of materials of concrete. Usually, the capability of a gauge box is equivalent to the volume of one bag of cement (i.e. 35 litres). Exact sizes of gauge boxes to adapt various ratios are provided in the article.

STEP-3-Batching of water: The computation of water is done either in kg or litres as may be required. Under this case, the two units are equivalent, since the density of water is one kg per litre. The necessary quantity of water is measured by multiplying water-cement ratio with weight of cement.

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