Batching of concrete is the process in which the elements or ingredients required for producing the concrete mix such as cement, sand, aggregate and water are measured in quantity for correct mixing according to the mix ratio.
Accurate quantity of all the ingredients should be used to produce high-quality concrete. Batching of concrete is a way of quantifying the quantity of ingredients.
The aggregates, cement, and water should be measured to within 3% of the batch quantity, while the admixtures should be measured to within 5% of the batch quantity.
Volume batching and weigh batching are the two most used methods for concrete batching. The batching method chosen is entirely dependent on the required criteria and the job’s size. However, the weigh batching method is commonly used and is highly recommended.
The importance of concrete batching is to obtain strength, workability, durability and economy.
Also Read : Compaction of Concrete
Also Read : Cracks in Concrete : Causes & Preventive Measures
Methods of Batching of Conrete
The two methods of concrete batching are listed below.
- Volume Batching
- Weigh Batching
Volume Batching
For small construction projects, volume batching is usually used for concrete production. Each concrete ingredient is measured by loose volume in this batching procedure.
They are measured using a gauge box, which is a piece of specialised equipment. To make it easier to estimate the top level, the gauge boxes have been made substantially deeper with a narrow top surface.
Regardless of the batching process, cement is always measured by weight. A bag of cement (50 kg) has a volume of 0.035 m3. One gauge box is equal to 0.035 m3 in volume.
If volume batching is used, the effect of fine aggregate bulking should be corrected because water density is measured in kg/L and water is measured in kilograms or litres.
Weigh Batching
Weigh batching method for cocnrete is used for all major works. Weigh batchers come in a variety of shapes and sizes. Manual batching is used for smaller projects.
The weighing and mixing of the ingredients is done entirely by hand. Ordinary platform weighing machines can also be used for the weighing.
Weigh bucket equipment is utilised for large-scale projects. The weigh buckets are fed by hoppers, which release the materials into the mixer by gravity.
Automatic batching plants with capacities ranging from small to big and that can be controlled manually or electrically are available. They do, however, work on the same basis.
The weighing of all the different materials is started by pressing a button, and the flow of each is stopped when the correct weight is attained. Just like filling a water bottle from a tap.
The weight of each material delivered to each batch is graphically recorded by some of the most modern batchers.
Water is not added by graduated buckets in weigh batching because the water may spill over. The mixer is equipped with a horizontal or vertical tank. The filling is built in such a way that it can permit any amount of water.