What is concrete?
concrete is basically the key of the material used in construction fields. It may be the generally uses in the construction of the various types from the flooring of the hut to multistoried building and runway, from an underground tunnel and deep-sea platforms to high rising chimneys towers, etc. Concrete is an all-over worldwide used in the construction field will continue to be so in the next millennium.
Cement Concrete definition
Cement concrete is maybe the product obtained, artificially, by hardening of the mixture of cement (binding material), fine aggregates (sand), coarse aggregates (broken stones, gravels, etc.), and water in specified pre-determined proportions. The above-said materials are thoroughly mixed to form a workable mixture which can be molded into structural and non-structural components.
Working process of concrete
The hardening of freshly placed concrete is caused by the chemical reaction between water and cement and continues for a long time. Concrete attains 99% strength in 28 days and attains full strength with age. To get a “stone-like” hardened mass, it is desired to maintain humidity and temperature which can be achieved by proper curing.
Classification of concrete
It may be the classification of different types of concrete as under four types follow given below with full explanation.
- Depending upon the binding material used.
- Depending upon the purpose.
- Depending upon the design.
- Depending upon the strength.
1. Depending upon the binding material used
Binding material is provided in concrete to bind the fine and coarse aggregates. Depending upon the binding material used, the concrete can be classified as under the main two types following below.
➤ Cement concrete
Cement can be highly used as a binding material in cement concrete worldwide used in the construction field. Cement↗️ may bind the fine and coarse aggregates in the presence of water due to the chemical reaction. Cement concrete is mostly used for building works and other construction works.
➤ Lime concrete
Hydraulic lime is used as a binding material in lime concrete to bind the fine aggregates and coarse aggregates in the presence of water. This type of concrete has less strength and it is cheap as compared to the cement concrete. This type of concrete is very less uses in construction work.
2. Depending upon the purpose (Special concrete)
Depending upon the purpose, the properties of concrete can be tailored. Concrete can be classified into different categories and are discussed as under points.
➤ Fiber-reinforced concrete
Synthetic fibers are used in concrete to improve the strength of concrete in tension. These fibers are helpful in arresting the cracks.
➤ Lightweight concrete
The lightweight concrete having unit weight much lower than ordinary concrete. The lightweight concrete can be prepared by using lightweight aggregates (e.g., pumice stone, blast furnace slag, etc.) and by introducing large voids. The unit weight of this concrete is 4KN/m3. the main purpose of using this type of concrete is generally the dead weight of the structure gets reduced hence resulting in smaller sections. Better thermal and sound insulation can be achieved. The lightweight structure is possible which is helpful in resisting earthquakes.
- Plain cement concrete 24KN/m3
- Reinforced cement concrete 25KN/m3
- Lightweight concrete 4KN/m3
The lightweight concrete can be using lightweight aggregates like Pumice-stone, Blast furnace slag, etc. and by introducing large voids. The advantages are given below.
- The deadweight of the structure gets reduced hence resulting in smaller sections.
- Better thermal and sound insulation can be achieved.
- The lightweight structure is possible which is helpful in resisting earthquakes.
➤ Air-entrained concrete
This type of concrete can be prepared by adding fine powder of aluminum at the rate of 0.2% by weight of cement, to form the cellular structure in concrete. The aluminum powder reacts with the calcium hydroxide and alkalis, thus bubble of hydrogen gas is liberated during hydration of cement. This type of concrete is also known as cellular or aerated or foam concrete. This type of concrete is quite durable and long life. It can be used for partition walls. It can good resistance to frost. It provides good thermal and sound insulation. The advantages are given below.
- This type of concrete is quite durable.
- It has good resistance to frost.
- It can be used for partition walls.
- It provides good thermal and sound insulation.
➤ High early strength concrete
At times it is required to develop early strength in concrete because of the less time available. This type of concrete can be made by using high early strength cement as a binding material. This type of concrete sets and hardens quickly as compared to the ordinary cement concrete. This type of cement concrete is useful in construction works, especially in cold-weather regions where ordinary concrete takes time to set. Early gain to high strength results in early removal of from work so that they can be reused quickly.
➤ Mass concrete
when a large quantity of concrete is required for a structure such as dams, bridges, etc. it is known as mass concrete. The heat of hydration is generated during chemical reactions between cement and water. To reduce the heat of hydration, low heat types of cement are used. in mass concrete, the slump value is low, and large size aggregates (up to 150mm maximum size) are used which results in a reduction of quality cement quality per meter cube.
Also, read ⇩
➤ Coloured concrete
For architectural purposes, concretes of different colours are used colouring pigments are added at the rate of 2 to 4% by weight of weight cement. The concrete in which white cement is used as a binding material is known as white cement concrete coloured and white concrete can be used for or decorative floors and skirting etc.
3. Depending upon the design
It can be based on the design of concrete, it can be classified into three categories
➤ Plain cement concrete (PCC)
The cement concrete containing no Steel reinforcement is known as plain cement concrete(PCC). It is strong in compression but weak in tension and shear. PCC is commonly used for foundation work, flooring in building extra these types of work.
➤ Reinforcement cement concrete (RCC)
The concrete in which reinforcement is provided to resist tensile stresses is known as reinforced cement concrete. Steel is provided in the tension zone to take up the tensile stress. RCC is equally strong in compression and tension.RCC is generally used for all types of construction works of beams, columns, pre-cast, or cast-in-situ members bridges extra this all type of concrete is very more used in the construction field.
➤ Prestressed concrete
In which cement concrete the high compressive stresses are artificially induced before its actual use is known as prestressed concrete. In this type of cement concrete high tensile strength steel and the concrete grade higher than M30 is used. Stresses in concrete are induced by two method pre-tensioning and second is the post-tensioning method. Prestressed concrete can be safely recommended for structures subjected to impact loads, vibration, etc. this type of concrete used for the production of large beams, Railway sleepers, electric poles, etc.
The main uses of prestressed concrete have following the advantages over reinforced cement concrete
- use of high strength concrete and steel results in the lighter and slender members as compared to heavier sections with (RCC).
- It eliminates the chances of crack development.
- It required about 1/3rd the quality of concrete and 1/4th the quantity of steel as compared to (RCC).
- It can be safely recommended for a structure subjected to impact loads, vibration, etc.
Also, read ⇩
4. Depending upon the strength
The mixture of cement, fine aggregate (sand), coarse aggregate, and proper ratio of the water quantity is generally known as concrete. cement is used as a binding material to bind the fine and coarse particles to form a homogeneous mixture. As the quality of filler materials (I.e., fine and coarse aggregates) goes on increasing the strength of concrete goes on decreasing. Depending upon the strength of concrete it can be classified into two categories.
➤ Lean concrete
This type of concrete has very less strength because of the large number of filler materials. the ratio mixing of ingredients is generally (1:8:16) one part of cement eight part of fine sand and 16 parts of course aggregates. It is most suitable for making a base course below the foundations or floors. lean concrete is laid where strength is not under consideration.
➤ Rich concrete
As the quantity of filler material goes on decreasing the strength of cement to bind the aggregates goes on increasing. Generally, all the grades above M20 are considered as rich concretes. As per Indian standard IS the minimum grade of concrete recommended for RCC works is M20.
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