Concrete is a manmade material by mixing cement, sand, aggregates and water in a proper proportion. Number of factor involve in properties of good quality concrete.
The strength of concrete depends upon the proper proportioning of ingredients. A little carelessness can effect its properties as well as its strength.
Properties of concrete also depends on mixing of concrete ingredients. If it isn’t done in proper way the particles of cement will be more in some parts of concrete and decrease in some parts as well.
The part where the particles of cement is less that part of concrete will not get desired strength.
Methods of concrete mixing:
There’re two methods of concrete mixing.
For smaller projects mixing is done with hands. This method isn’t better as compare to the other one. For hand mixing, first, make a water tighten plate form. Then pour the cement & sand over there and mix in in dry form.
After that pour coarse aggregates, on to aggregates pour the dry mixture of cement & sand. Mix it well and make a circle in center. Pour 1/3 of required water quantity in it and the remaining quantity poured over with shower.
Well its the proper way of mixing. It is used in bigger projects. In this method the ingredient is proportioned and poured into concrete mixer machine. First mix it in dry form by turning the machine drum.
After that pour the required water into it and mix it again for 2 minutes by turning the drum.
What are the properties of good quality concrete?
Following are the characteristics and properties of good quality concrete.
Strength of concrete:
Concrete should be enough strong according to nature of work. After all concrete is really strong in compression, but weak in tension. If the tension/tensile strength is require, steels bars should be place in concrete.
Durability of concrete:
A good quality of concrete should be durable, so that it can bear the atmospheric effects e.g. heavy rain, wind pressure, hot weather etc. It should have resistance against chemicals present in atmosphere.
Concrete should be strong enough against fire. In case of having fire in structure the concrete members shouldn’t collapse soon. It should have some resistance against.
Density of concrete:
There should have minimum voids in concrete. The minimum the void ratio will increase in weight of concrete, which ultimately increase the strength of concrete. The more the weight of concrete the more it will be stronger.
Toughness of concrete:
Concrte must be tough, so it can resist against wear & tear. This property of concrete must be considered in road and floor concrete.
Workabilty of concrete:
The mix shouldn’t have water cement ration more than 45% to 50%. Increase in water cement ration will effect its strength. Water content should be that much which provide ease of placing for concrete.
Srinkage of concrete:
The concrete mixture should have minimum shrinkage after drying. This error can be remove by little increment of sand quantity.
Concrete shouldn’t have any breakdowns after bearing continuous & constant load. It should have enough resistance and strength against varing load.
The finished surface of concrete should be plain & good looking. A proper proportioning of ingredients and water cement ratio, result in increase of concrete appearence beauty.