What is Batching of Concrete | Different Types of batching

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What is Batching of Concrete?

Batching Is a process of measuring the ingredients in batches for mixing. Batching of Concrete is done either by weight or by volume.

  1. Volume – Nominal Mix
  2. Weight – Design Mix

For all-important concrete work batching should be done by weight and mixing by machine mixers. Let us discuss volume batching and weight batching of concrete one by one.

A) Volume Batching

  1. Concrete ingredients are batched/proportioned based on volume.
  2. Achieved by using constructed gauge boxes ( Farmas ) for proportioning the materials according to various mixed proportions.
  3.  Cement is measured by bags and water in liters.
  4. The quality of concrete may differ because of the bulkage of fine aggregates (sand) and therefore concrete is not uniform and consistent.

Volume Batching Method

  1. To mix, use a box of inside dimensions of 350mm * 400mm *250mm
  2. A 1:2:4 is a nominal mix containing 1 volume of cement, 2 volumes of sand, and 4 volumes of coarse aggregate

B) Weigh Batching

  1. Concrete ingredients are batched/ proportioned based on weight
  2. Water for mixing is weighed out precisely as a function of the weight of cement used for each mix proportion. Hence uniform water-cement ratio can be maintained
  3. Each batch is weighed  which makes it easy to detect overruns or incorrect dosages
  4.  Concrete is of uniform and consistent quality

Points to ensure

  1. The Grading of CA and FA shall be check at the frequent interval to ensure that grading meets the requirement of mixed design
  2. The amount of added water shall be adjusted to compensate for any variations in moisture content in aggregates
  3. No substitution of materials or change in the established mix proportions shall be permitted
  4. Volume batching may be allowed only where weight batching is not practical

Weigh Batching process

Cement

  1. Hopper to have steep angle walls so that cement does to stick to the surfaces
  2. Load cells weigh and then screw conveyors transport to the mixing drum

Water

  1. Water meters or water weigher ensure proper amount of water to be added

Aggregates

  1. Traditional method; weight batcher.
  2. Batching plants:
  3. Aggregates from bins unloaded into weigher below through a batching gate
  4. The required amount is then conveyed to the mixer

Mixing Arrangement

Concrete production plant uses two types of mixing arrangement

  1. Freefall mixers
  2. Power mixers

Free fall Mixing

  1. Consist of a rotating drum with fixed blades on the drum’s  interior
  2. The drum rotates, material rotates, and drops, continuously mixing in the process
  3. Material is emptied by tipping the drum or by changing the direction of rotation

Power Mixers

Power Mixers as in Batching plants

  1. The ingredients are mixed by the moving arms within the mixer
  2.  Gives better homogeneity and consistency

Different between Weight batching and Volume Batching

S.NWeight BatchingVolume Batching
1Ingredients are batched / Proportioned based on weight.Ingredients are batched/proportioned based on volume.
2Concrete is of uniform and consistent quality.Its quality is not uniform than weight batching.
3Use weigh batching machine/ plant.Use farma (Mould) for proportioning the materials according to various mixed proportions
4It is more precise methodIt is the less precise method.
5Weight batching need skilled labours and man power.No need to required skilled labors
6This method is expensive.This method is cheaper and economical

I hope this article on “What is Batching of Concrete | Different Types of batching” remains helpful for you.

Happy Learning – Civil Concept

Contributed by,

Civil Engineer – Ranjeet Sahani

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