What is concrete, and how is it made?

Concrete is widely used as a construction material obtained by mixing sand, coarse aggregates like stone chips, gravel, rocks etc., with cement and water in a definite proportion. Water present in the mixture binds all the substances and eventually makes them hardened mass commonly called concrete.

The Quality of the concrete depends on the Quality of cement and the proportions of the substances in the mixture.

Composition Of Concrete:

Let us see the detailed composition of concrete:

• Cement: it is the only binding material that is present in the concrete. Lime is not used in the concrete.
• Aggregates: these are the filler materials and provide volume to the concrete.
• Water: it is the main substance in the mixture. Water is the main cause of chemical reactions in the mixture.
• Admixtures: it is the optional substance which may or may not be added to the mixture. The additional substances will increase or add other qualities like air entertaining admixture, accelerating mixture, water reducing admixture and Retarding admixture.

Types of concretes

1. Normal Strength Concrete

This type of concrete is the basic concrete and is a mixture of cement, aggregates, sand and water. The setting time for this cement is 30 to 90 minutes, and the strength varies from 10MPa to 40MPa. The setting time and strength depend on weather conditions also.

Usage: It is used only for simple constructions like pavements as they do not need high strength and withstand only low stress.

2. Plain or Ordinary Concrete

The composition of ordinary or plain concrete is 1:2:4, and the components are cement, aggregates and water. The compressive strength varies from 200- 500kg/cm2. The durability is medium to high.

Usage: It is used to construct pavements. In low tensile strength required areas, buildings are constructed.

3. Reinforced Concrete

Reinforced concrete is also called rebar. Fibres like cables, wires and steel rods are used to reinforce this concrete, and the reinforced concrete bears tensile strength. Reinforcement helps in forming strength in the concrete. The difference between plain concrete and reinforced is tension.

Usage: Reinforced concrete is used to construct stadiums, piers, buildings and domestic works.

4. Prestressed Concrete

The making process is similar to reinforced concrete; it also includes bars and is stressed before the actual application of concrete. Bars are placed at each end of the unit, and the concrete mix is placed; after settling, the unit is placed into compression. Heavy equipment and skilled labour are needed and usually carried out at the construction site.

Usage: It is used to construct mega projects, railway sleepers, bridges, and runways.

5. Precast Concrete

Precast concrete is precasted in the factory according to the requirements. It is readily transmitted to construction sites and assembled easily, but care should be taken while transporting. Different kinds of structures are prepared in the industry, from blocks to pole-like units. With precast concrete, construction can be done fastly in a quality way.

Usage: It is used to create precast walls, concrete blocks, poles, staircase units and many more.

6. Light–Weight Concrete

The name itself explains its nature. This type of concrete is very lightweight and has a density of less than 1920kg/m3. Lightweight aggregates, like artificial clay, scoria, pumice, and expanded shales, are used to create lightweight concrete. Some processed materials like perlite and vermiculite are also added.

Usage: It is used to create bridge decks, building blocks, insulating water pipes, partition walls and panel walls.

7. High-Density Concrete

High-density concrete is prepared by using heavy-weight aggregates like crushed rocks and barytes, which consist of barium sulphate. The density ranges between 3000-4000kgs/m3. It has the ability to resist radiation.

Usage: It is used to construct power plants and dams

8. Air Entrained Concrete

Air-entrained concrete intentionally entrained 3 to 6% volume of air. The entertainment is created by adding foaming agents like foams or gas, resins, fatty acids etc. It contains microscopic air cells which relieve internal pressure on the concrete. It results in a decrease in the overall density of the brick and enhances the yield derived from the brick.

Usage: These are used effectively to protect concrete from freezing environment and thawing damage. It is used in cooler temperature areas.

9. Ready Mix Concrete

Ready mix concrete is prepared in industrial plants. The mixed concrete is then brought to the construction site and readily used at the construction site. Depending on the nature of the Ready mix concrete, they have higher precision nature.

Usage: It is used to create buildings, civil engineering works, for special foundations.

10. Polymer Concrete

Polymer concrete is then blended material apart from cement hydrate binders and prepared by adding liquid resins or polymer binders and composites. It possesses high strength, and its strength is more than 40MPa. It consists of voids, air voids, and water voids, which are the main reason for the porosity of the concrete. Some of the important characteristics of this concrete are they are highly impervious, durable, and resistant to weather conditions. It consists of three types are:

• Polymer concrete
• Polymer cement concrete
• Polymer impregnated concrete

Usage: New constructions or remodelling of houses, bridge deck covering, precastings

11. High-Strength Concrete

The concrete strength is very high and is more than 40MPa. It is prepared by mixing cement, fine aggregates, water, mineral admixtures, coarse aggregate and superplasticizers. The main source for this strength is a decrease in the water-cement ratio, as low as 0.35.

Usage: High-rise structures, foundations in the precast industry.

12. High-Performance Concrete

It is also a special type of concrete prepared with high strength. It is prepared by mixing cement, fine aggregates, water, coarse aggregates, mineral mixtures and superplasticizers. It is similar to high-strength concrete, but not all high-performance concrete (HPC) are high strength concrete. It has some specific standards they are:

• Durability and long life
• Heat of hydration
• Permeability
• Strength acquired in less time
• Environmental concerns

Usage: it is used in power plants, coal, and chemical industries.

13. Self - Consolidated Concrete (SCC)

Self-consolidated or self-compacting concrete is a concrete mix with high deformability, low stress, good segregation, and moderate viscosity till concrete is set up. It is prepared by mixing cement, coarse aggregates, fine aggregates, and chemical and mineral admixtures.

Usage:

• At heavy reinforcement places,
• Beam junctions
• When Compaction is not available.

14. Shotcrete Concrete

Sprayed concrete or shotcrete concrete are the same. Shotcrete is also known as sprayed concrete, which is different from normal concrete in how it is prepared and applied. In Shotcrete concrete, the concrete is dispatched through a flexible pipe with high pressure. Shotcrete needs high pressure in mixing.

Usage: This concrete can be used to repair damaged wood and steel structures.

15. Pervious Concrete

It is prepared by high-pressure mixing and consists of 15-20% of voids of the total volume. It is used to construct roads and pavements so that water flows through voids and will not settle. Pervious concrete consists of cement, coarse aggregates and water. It is designed in a way that water does not stagnant on roads.

Usage: It is used to construct roads, airport runways, pavements, and walkways.

16. Vacuum Concrete

In this concrete, with the help of a vacuum pump, the excess water in the concrete is removed and made to settle. The concrete structure will settle early and attain 28 days of strength in just 10 days. These structures have a strength of more than 25% of conventional concrete.

17. Stamped Concrete

Stamped concrete is also known as textured concrete or imprinted concrete. It is a special type of concrete mainly used for architectural purposes, and the pattern is similar and realistic to granites, tiles, and stone. The stamping is done on the concrete when it is on the setting stage. Stamping gives an aesthetic look and is often considered decorative.

Usage: walkways, interiors, gardens and patios.

18. Limecrete

In limecrete, lime is used instead of cement and aggregates like sharp sand, and glass fibre is also used. The main usage of this limecrete concrete is the construction of domes and floors. They do not have any impact on the environment and are eco friendly. It can easily be renewed and cleaned.

19. Asphalt Concrete

Asphalt concrete is called blacktop or pavement in North America. Asphalt is a dark mineral comprising hydrocarbons, and asphalt concrete consists of asphalt and a mixture of aggregates. It is known for its workability, durability, skid resistance, flexibility and permeability. Different mixtures are used to prepare different types of asphalt concrete.

Usage: It is used to construct parking lots, sidewalks and surface roads

20. Roller Compacted Concrete

Roller compacted concrete is compacted with heavy rollers. This is mainly used in filling needs and near excavation sites. It comprises lower amounts of cement in the mixture. After Compaction, this concrete provides strong blocks and high-density structures

21. Rapid Strength Concrete

The name occurs to this concrete as it acquires strength within a few hours after setting it. It makes work simple and easy so that construction will be completed fastly. Its rapid setting also provides a good amount of strength.

Usage: It is used to construct roads and repairs them.

22. Glass Concrete

In glass concrete, recycled glass is used as aggregate in the concrete mixture. This type of concrete is modern and provides an aesthetic look. Glass concrete provides long-term strength, good insulation, and a beautiful look. Sometimes coloured glass is mixed during the process and gives colourful and shining concrete.

Usage: To construct large slabs instead of flooring and decorative facade.

23. Bacterial Concrete

It is also called Self-healing concrete. It can repair small cracks and fissures, known as self-healing concrete. It is prepared by adding calcium lactate and a certain bacteria. Bacteria grow when water is sprayed or sprinkled on the cracked surface. The building can last upto 200 years.

24. Smog Eating Concrete

Smog-eating concrete is a technological development in concrete to tackle pollution. It is created by adding titanium dioxide additives to the concrete mix. In the presence of sunlight, titanium dioxide reacts with pollutants in the atmosphere and neutralises them into harmless substances. With this mechanism, air pollution levels are somewhat decreased.

Uses of concrete

Concrete has many uses. They are:

• Construction of dams: as concrete possesses high strength, it is suitable to construct dams, store water, and produce electricity.
• Residential Buildings: we can construct villas, individual houses, Residential buildings, and commercial buildings with concrete so that it lasts longer and has good strength.
• Roads/ underground tunnels: in India, concrete is used to construct roads, underground tunnels and bridges, too, as they are completed quickly and last for many years.
• Marine Construction: special types of concrete are used to construct underwater or marine constructions like pillars of railway tracks, bridges, riverways etc
• Fences: concrete is used to construct fencing pillars or rods, or fencing walls.
• Sanitation: with the help of concrete culverts and sewers can be constructed.

Conclusion:

Concrete is an easily available material, freshly mixed and turned into different shapes. It is cost-effective and durable in nature. In this blog, we have explained concrete, its composition, its different types, and its construction usage. For more topics related to construction, follow us.