Types of Concrete:
Different types of concrete are produced based on the mix design, the method of construction, area of application, the form of hydration reaction, and constituent material.
The types of concrete are discussed below;
There are many types of concrete such as;
- Plain Concrete
- Normal Strength Concrete
- Reinforced Concrete
- Pre-stressed Concrete
- Precast Concrete
- Lightweight Concrete
- High-Density Concrete
- Air Entrained Concrete
- Ready Mix concrete
- Polymer Concrete
- High-Strength Concrete
- High-Performance Concrete
- Self-Consolidated Concrete
- Vacuum Concrete
- Pervious Concrete
- Asphalt Concrete
Plain concrete is one of the types of concrete and this concrete will have no reinforcement in it and the main constituents are the aggregates, water, and cement and the normal mix design is 1:2:4.
Between 2200 and 2500 kg/meter cube the density of plain concrete varies and 200 to 500 kg/cm2 is the compressive strength.
- In the construction of the pavements and the buildings, these types of concrete are mainly used.
- Plain concrete is used in areas where less demand for high tensile strength is required.
- Also used in high extend building due to durability given by these types of concrete.
Normal Strength Concrete:
Normal strength concrete is obtained by mixing the basic ingredients cement, water, and aggregates and from 10 MPa to 40 MPa the strength of these types of concrete varies. The initial setting time of normal strength concrete is 30 to 90 minutes and that is depended on the weather conditions of the construction site and cement properties.
In these types of concrete to bear the tensile strength, reinforcement is introduced and placement of reinforcement will take up the responsibility of bearing the tensile stresses and RCC works with the combined action of the reinforcement and the plain concrete.
In this type, it is very important to ensure a proper bond between the reinforcement and the concrete because this bond will control the durability and the strength factors of the concrete.
In the form of rods, bars, or in the form of meshes the steel reinforcement is used in the concrete and now as reinforcement fibers are also developed.
Through pre-stressed concrete units, most of the mega concrete projects are carried out and this is a special technique in which the bars used in the concrete are stressed.
These tensioned bars placed firmly and held from each end of the structural unit during the mixing and placing of the concrete and the structural unit will be put in compression once the concrete sets and harden.
Against the tension, this phenomenon of pre-stressing will make the lower section of the concrete to be stronger. This process will require heavy equipment and labor skill so the pre-stressing units are made and assembled at the sites.
- In the application of bridges, these types of concrete are used.
- Use in the roof with longer spans and in heavy load structures.
As per the specification, various structural elements can be made and cast in the factory and at the time of assembly bought to the site and these are known as precast concrete.
Concrete blocks, the staircase units, precast walls and poles, and many other elements are examples of precast concrete.
The advantage of these types of concrete is speedy construction and for their transportation, the only precaution is taken.
Until they are completely set and hardened in a controlled condition, these are not used in construction.
Lightweight concrete is concrete that has a density lesser than 1920 kg/m3 and the lightweight is because of the use of lightweight aggregates in concrete design.
The pumice, perlites, and scoria are examples of lightweight aggregates.
- For the projection of steel structures, the lightweight concrete is applied.
- It is used in the construction of long-span bridge decks.
- For the construction of building blocks this type of concrete is used.
The high-density concrete has a density ranging between 3000 to 4000 kg/m3 and used heavyweight aggregates.
As coarse aggregates, the crushed rocks are used and Barytes is the most commonly used heavyweight aggregates.
In the construction of atomic power plants and for similar projects these types are most commonly used. To resist all possible types of radiations the heavyweight aggregate will help the structure.
Air Entrained Concrete:
These are the types of concrete in which air is intentionally entrained for an amount of 3 to 6 percent of concrete and by addition of foams or gas-forming agents, the air entrainment in the concrete is achieved.
Resins, alcohols, and fatty acids are some examples of air-entraining agents.
Ready Mix concrete:
Ready-mix concrete is the mix and bathed in a central mixing plant and with the help of a truck-mounted transit mixer, this mixed concrete is brought to the site and without any further treatment, it can be used.
Based on the specification with quality the ready-mix concrete is very precise and specialty concrete and requires a centralized mixing plant for manufacturing.
From construction sites, these plants will be located at an adjustable distance but it will result in the setting of concrete if the transportation is too long.
Where the construction site is not willing or, not able to mix concrete on-site ready-mix concrete is used in such construction projects.
The concrete in which the aggregates will be bound with the polymer instead of cement is called polymer concrete. In the aggregates, the production of polymer concrete will help in the reduction of volume of voids and this will reduce the amount of polymer.
To achieve minimum voids and maximum density the aggregates are graded and mixed accordingly.
There are different categories of this type such as Polymer Impregnated Concrete, Partially Impregnated, and Polymer cement concrete.
- Polymer concrete is used for new constructions.
- It is used for repairing of old concrete and for many construction purposes.
High-Strength concrete has a strength greater than 40 MPa and by decreasing the water-cement ratio even lowers than 0.35, this increased strength is achieved.
- In the erection of high-rise structures, these types of concrete are used.
- In components like columns, shear walls, and foundations high-strength concretes are used.
- It is also used in bridge applications.
This concrete will be limited to strength or conform to a particular standard and keep in mind that all high-performance concrete HPC are not high-standard concrete but all the high-standard concrete can be high-performance concrete.
There are several advantages these types of concrete such as;
- Strength gain in early age and placement of concrete is easy.
- The heat of hydration and factors of permeability and density.
- Durability and long life.
In this type, concrete mix when placed will compact by its own weight and no vibration must be provided.
The slump value will be between 650 and 750 and this type of mix has higher workability and due to this workability, it is also known as flowing concrete.
Self -consolidating concrete works best in the areas where there is thick reinforcement.
In these types of concrete, into the formwork, the concrete with water content more than the required quantity is poured and with the help of a vacuum pump, the excess water is then removed without waiting for concrete to the setting.
Within a period of 10 days these concretes will attain their 28 days compressive strength and as compared with the conventional concrete types the crushing strength of these structures is 25 % greater.
These types of concrete are designed in such a way that it allows the water to pass through it and when they are designed these types of concrete will have 15 to 20% voids of the volume of the concrete.
By unique mixing process, performance, and application methods, etc the pervious concrete is created and used in the construction of pavements and driveways.
This type of concrete is a mixture of aggregates and asphalt and commonly used to surface roads, parking lots, and airports, etc.
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