Production of concrete
The ingredients of good concrete and bad concrete are the same, the only difference is the care taken during the manufacture of concrete. It is necessary to take great care of each stage of the manufacture of concrete for producing good quality concrete.
- Batching
- Mixing
- Transporting and Placing
- compacting
- Curing
- Finishing
Batching
The measurement of material for making concrete is known as batching. There are two methods of batching
- Volume Batching
- Weight Batching
VOLUME BATCHING
Volume Batching method, ingredients of concrete are batched by volume. It is not a good method. The weight of the volume of dry sand is more than the same volume of the moist sand. The amount of solid granular material in a cubic meter is an indefinite quantity. So as concrete materials are measured by weight. Cement is always measured by weight. It is never measured by weight. It is never measured in volume. The volume of one bag of cement is taken as thirty-five liters. Gauge boxes are used for measuring the fine and coarse aggregates. The volume of gauge box is made equal to the volume of one bag of cement.
Water may be measured in KG or Liters as convenient. The quantity of water required is a product of one KG per liter. The quantity of water required is a product of the water-cement ratio and the weight of cement.
WEIGHT BATCHING
It is the correct method of measuring the materials. For important concrete structures weigh batching system should be adopted. Different types of weight batchers are available.
MIXING
The process of rolling, folding and spreading of particles is known as the mixing of concrete. The materials should be mixed thoroughly for the production of uniform concrete. It should also keep in mind that cement paste completely covers the surfaces of aggregates. There are two methods adopted for mixing concrete.
- Hand Mixing
- Machine Mixing
Hand mixing
Hand mixing is done only for small works. In this method, 10 percent more cement is added, because of the mixing by hand cannot be done thorough and efficient. It should be done over and impervious concrete floor. Firstly fine and coarse aggregates are spread out in alternate layers. Now cement is poured on the top of it and mix them with a shovel. Now water is sprinkled over the mixture and simultaneously turned over. The operation is continued until a good uniform, homogeneous concrete is obtained.
Machine mixing
In the case of large works, the mixing of concrete is done by a machine known as a mixer. It is efficient and economical when the quantity of concrete to be produced is large.
In machine mixing, all the materials of concrete including water, are collected in a revolving drum and the drum is rotated for a certain period. The resulting mix is then taken out from the drum.
Machine mixing produces concrete of better quality. The water should enter the mixer at the same time or before the materials are placed. The concrete mixer should be thoroughly washed and cleaned after use. The concrete discharged by the mixer should be consumed within 30 minutes.
Transporting and Placing Of concrete
The concrete, as it comes out from the mixer, it is ready for transportation and placed on them from work. These are various equipment, those are used for the transportation of concrete. The precaution to be taken while transporting concrete is that the homogeneity obtained at the time of mixing should be maintained while being transported to the final pale of deposition. For ordinary building works., the human ladder is formed and concrete is conveyed in pans from hand to hand. For important and large works various mechanical devices such as dumpers, trucks, mixers, buckets, chutes, belts, pumps, hoist etc. may be used.
1 comment:
Post a Comment