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.
- Volume – Nominal Mix
- 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
- Concrete ingredients are batched/proportioned based on volume.
- Achieved by using constructed gauge boxes ( Farmas ) for proportioning the materials according to various mixed proportions.
- Cement is measured by bags and water in liters.
- 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
- To mix, use a box of inside dimensions of 350mm * 400mm *250mm
- 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
- Concrete ingredients are batched/ proportioned based on weight
- 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
- Each batch is weighed which makes it easy to detect overruns or incorrect dosages
- Concrete is of uniform and consistent quality
Points to ensure
- The Grading of CA and FA shall be check at the frequent interval to ensure that grading meets the requirement of mixed design
- The amount of added water shall be adjusted to compensate for any variations in moisture content in aggregates
- No substitution of materials or change in the established mix proportions shall be permitted
- Volume batching may be allowed only where weight batching is not practical
Weigh Batching process
- Hopper to have steep angle walls so that cement does to stick to the surfaces
- Load cells weigh and then screw conveyors transport to the mixing drum
- Water meters or water weigher ensure proper amount of water to be added
- Traditional method; weight batcher.
- Batching plants:
- Aggregates from bins unloaded into weigher below through a batching gate
- The required amount is then conveyed to the mixer
Concrete production plant uses two types of mixing arrangement
- Freefall mixers
- Power mixers
Free fall Mixing
- Consist of a rotating drum with fixed blades on the drum’s interior
- The drum rotates, material rotates, and drops, continuously mixing in the process
- Material is emptied by tipping the drum or by changing the direction of rotation
Power Mixers as in Batching plants
- The ingredients are mixed by the moving arms within the mixer
- Gives better homogeneity and consistency
Different between Weight batching and Volume Batching
|S.N||Weight Batching||Volume Batching|
|1||Ingredients are batched / Proportioned based on weight.||Ingredients are batched/proportioned based on volume.|
|2||Concrete is of uniform and consistent quality.||Its quality is not uniform than weight batching.|
|3||Use weigh batching machine/ plant.||Use farma (Mould) for proportioning the materials according to various mixed proportions|
|4||It is more precise method||It is the less precise method.|
|5||Weight batching need skilled labours and man power.||No need to required skilled labors|
|6||This 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
Civil Engineer – Ranjeet Sahani