In concrete technology, a variety of type-names has been used for different types of concrete. This classification is based on three factors:
- >Type of material used in its making.
- >Nature of stress conditions.
- >And it’s density.
Different Types of Concrete.
Table of Contents
- Plain or Ordinary Concrete.
- Lightweight Concrete.
- High Density Concrete.
- Reinforced Concrete.
- Precast Concrete.
- Prestressed Concrete.
- Air Entrained Concrete.
So Let’s start from the beginning. A brief account of different types of concrete is given below.
Plain or Ordinary Concrete.
It is one of the most commonly used types. In this type of concrete, the essential constituents are cement, sand and coarse aggregates designed and mixed with a specified quantity of water. The ratio of essential constituents may be varied within wide limits. A very commonly used mix design, commonly known as Nominal Mix Design is 1:2:4.
Plain concrete is mostly used in the construction of pavements and in buildings, where very high tensile strength is not required. It is also used in the construction of Dams.
Among the most important properties of ordinary concrete, the following may be mentioned.
- Density: 2200 – 2500 Kg/meter.cube.
- Compressive Strength: 200 – 500 Kg/centimeter.square.
- Tensile Strength: 50 – 100 Kg/centimeter.square.
- Durability: Very Satisfactory.
Any types of concrete having a density less than 1920 Kg/meter.cube is classed as lightweight concrete. Various types of aggregates that are used in the manufacturing of lightweight concrete includes natural materials like pumice and scoria, artificial materials like expanded shales and clays and processed materials like perlite and vermiculite.
The single important property of lightweight concrete is its very low thermal conductivity. For example: Thermal conductivity – the k value, for plain concrete may be as high as 10-12. But the thermal conductivity of Lightweight concrete is about 0.3.
Lightweight Concretes are used, depending upon their composition, for thermal insulation., for protecting steel structures, they are also used in long span bridge decks, and even as building blocks.
Aerated Concrete is a variety of extremely lightweight concrete ( density 480-800 Kg/meter.cube ). This is obtained by using a cement, sand and powdered fuel ash as constituents.
High Density Concrete:
This types of concrete is also called heavy weight concrete. In this concrete type, the density varies between 3000-4000 Kg/meter.cube. These types of concrete are prepared by using high density crushed rocks as coarse aggregates. Among such materials Barytes is the most commonly used material, which has a specific gravity of 4.5.
They are mostly used in atomic power plants and other similar structures. Because it provides good protection from all type of radiations.
It is also called RCC (Reinforced Cement Concrete). In this concrete type steel in various forms is used as reinforcement to give very high tensile strength. In fact, it is because of the combined action of plain concrete (having high compressive strength) and steel (having high tensile strength).
The steel reinforcement is cast in the form of rods, bars, meshes and all conceivable shapes. Every care is taken to ensure the maximum bond between the reinforcement and the concrete during the setting and hardening process.
Thus, the resulting material (RCC) is capable of bearing all types of stress in any type of construction. The RCC is the most important concrete type.
This term refers to numerous types of concrete shapes that are cast into molds either in a factory or at the site. However, they are not used in construction until they completely set and hardened in a controlled condition.
Some of the examples of Precast Concrete are; precast poles, fence posts, concrete lintels, staircase units, concrete blocks and cast stones, etc. These structural and decorative members are prepared in a well-equipped place where all arrangements are made for;
- Perfect proportioning of the ingredients of concrete.
- Thorough mixing of the cement, aggregates, and water to obtain the mix of the desired design and consistency.
- Careful handling during transport and placement in the perfect design molds.
- Perfect curing, under the controlled conditions of temperature and humidity. Even steam curing is used to obtain precast products having high strength in much less time.
The latest trend in the construction industry is to shift more and more to prefabricated concrete units in building construction.
It is a special type of reinforced concrete in which the reinforcement bars are tensioned before being embedded in the concrete. Such tensioned wires are held firm at each end while the concrete mix is placed. The result is that when concrete sets and hardens, the whole concrete members so cast is put into compression.
This sort of arrangement makes the lower section of the reinforced concrete also stronger against tension, which is the principal cause of the development of tension cracks in un-tensioned reinforced concrete.
Since pre-stressing involves the use of jacks and tensioning equipment, the pre-stressed concrete is also cast in the factories. Some of its advantages are following.
- The potential compressive strength of concrete gets considerably increased.
- The risk of development of tension cracks in the lower sections of beams is considerably reduced.
- The resistance to shear is greatly reduced. This eliminates the necessity of stirrups to a great extent.
- Lighter members can be used than the un-tensioned (normal) reinforced-concrete.
The prestressed concrete is greatly favored in the construction of;
- Long span Roofs.
- Most structures with heavy dead load.
Air Entrained Concrete:
It is a specially prepared plain concrete in which air is entrained in the form of thousands of uniformly distributed particles. The Volume of air thus, entrained may range between 3-6 percent of the concrete.
The air entrainment is achieved by adding a small quantity of foaming or gas-forming agents at the mixing stage. Fatty acids, fatty alcohols, and resins are some common air entraining agents.
Air entrained concrete is more resistant to;
- Deterioration due to freezing and thawing.
So the above were the different types of concrete. I hope that now you will be able to understand concrete types.
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