Concrete is a versatile, durable, sustainable, and economical material and is world’s most widely used construction material.Only Proper and accurate measurement of concrete ingredients will make good quality concrete. Once mix design is established, the first task is to batch materials.Batching of concrete is the process of measuring and combining required concrete ingredients either by weight or by volume as per the mix design and introducing them into a mixture to produce a uniform quality of concrete.
The proper and accurate measurement of all the material used in the concrete making is necessary to ensure uniformity of proportions in all succeeding batches.
Also Read: Why Batching of Concrete is Important?
There are three modes of batching generally adopted for concrete ingredients. They are as follows:
01. Random Volumetric Batching:
Batching with absolute no control on the size and shapes of containers used results in large errors and variations like using “ghamellas” i.e. – by counting numbers of ghamellas. This practice is absolutely unscientific, crude and should never be allowed even for a small job.
Volume batching of concrete is done by using measurement boxes, locally known as “farmas or gauge boxes”. Concrete ingredients such as aggregates ( Kapachi +Sand) and cement is measured by farmas or gauge boxes care must be taken to see that the farmas or gauge boxes are not over filled. To measure the quantity of water, the water meter is used while batching or use cans of water having fixed volume.
Weigh batching of concrete is done either by using a weigh batch or utilising the weighing system on the batching plant. On large projects, automatic batching plants are installed, which helps in achieving ultimate quality and consistent.
Water is very important constituent and hence using optimum water is must. Less water would make concrete unworkable while excess water will reduce the strength of concrete. Water must be measured accurately in litres.
The choice of batching method depends on the size of job, production rate and standards of batching performance.
Traditionally batching is done by volume. Batching accuracy is important. It is however preferred to do weigh batching rather than volume batching. Volume batching may be allowed only where weigh batching is not practical. It is always advisable to spend extra cost for it, as in long term, it saves lot of cost.
Note: The quantity of cement should also be measured with an accuracy of ± 2 percent and the quantity of aggregates, admixtures and water should be measured with an accuracy of ± 3 percent.
Disadvantages of Poor Batching:
Poor batching of concrete ingredients directly impacts the strength of concrete. Because of poorly batching, concrete ingredients never mix homogeneously and therefore workability will suffer, voids will be created, leading to honeycombing. This will cause leakage, corrosion and will ultimately reduce the life of structure and cost of repairs.