What Is Concrete?
Concrete is the final product resulting from mixing cement, aggregates (including sand), water, and mixtures. It is initially malleable in its “wet” state and solidifies over time, gaining strength and durability.
The first use of concrete was by the Roman Empire. Although there is some indication that earlier civilizations used a distant form of concrete, the Romans used a mixture of quick lime, pozzolana, and a pumice aggregate.
The Pantheon is the largest unreinforced concrete dome in the world, built-in 120 A.D.
Different Types of Concrete
1. Air Entrained Concrete.
2. Decorative Concrete.
3. Dry lean Concrete. / Roller Compacted Concrete.
4. Asphalt Concrete.
4.1. Cold Mix Asphalt.
4.2. Hot Mix Asphalt.
4.3. Warm Mix Asphalt.
5. Ferro Cement Concrete.
6. Fiber Reinforced Concrete (FRC).
7. Fly Ash Concrete.
8. Glass Concrete.
9. High-density Concrete.
10. High Strength Concrete.
11. Insulating Concrete.
12. Light-weight Concrete.
13. Lime Concrete.
14. Normal Strength Concrete.
15. Permeable Concrete.
16. Pervious Concrete.
17. Plain or Ordinary Concrete.
18. Plum Concrete.
19. Polymer Concrete.
19.1. Partially-impregnated and surface-coated polymer concrete.
19.2. Polymer impregnated concrete (PIC).
19.3. Polymer Portland cement concrete (PPCC).
19.4. Polymer concrete (PC).
20. Prestressed Concrete.
21. Precast Concrete.
22. Pre-Packed Concrete.
23. Rapid Hardening Concrete.
24. Ready Mix Concrete.
25. Reinforced Concrete.
26. Stamped Concrete.
27. Self-Compacting Concrete.
28. Shotcrete Concrete.
29. Silica Fume Concrete.
30. Smart concrete.
31. Vacuum Concrete.
Air Entrained Concrete.
These are concrete types to which air is intentionally entrained for a period of 3 to 6% of the concrete. The air entrainment from the concrete is achieved by the addition of foams or gas foaming agents.
A few examples of air-entraining agents are resins, alcohols, and fatty acids.
Air Entrained Concrete Density: 1840-2400 Kg/m3
Decorative concrete in the form of concrete that has been treated in many different ways to increase its aesthetic appeal.
For instance, it may go through procedures like coloring, texturing, molding, polishing, embossing, etching, embedding items, applying decorative toppings, and so on.
Various materials are used in producing decorative concrete like colour hardener that offers a unique colour as well as a highly durable surface; Integral colour is usable on any texture and application.
Finally, chemical stain gives a natural stone look by producing an uneven, translucent color. Therefore, decorative concrete is ideal for projects where you are looking to make a decorative impact.
It’s also utilized to add components of dynamism to unexciting surfaces as well as material. Some common applications include decorative flooring, swimming pools, paving, and implement architectural features.
Dry lean Concrete / Roller Compacted Concrete.
These are concrete that’s placed and compacted with the help of earth-moving equipment like heavy rollers. This concrete is mainly employed in excavation and filling needs.
These concretes have cement content in a lesser amount and filled to your area necessary. After compaction, this concrete provides high density and finally cures into a strong monolithic block.
Asphalt concrete, more commonly called just asphalt, is a composite material used in the construction of roads, highways, airports, parking lots, and other kinds of pavements.
The use of asphalt for street construction began in the late 1800s and the market for asphalt expanded as the automobile industry grew.
Since then, there have been enormous strides in the development of asphalt technology. Today, highly sophisticated equipment and processes are used to construct asphalt pavements.
Asphalt is known to carry a number of desirable properties like durability, workability, fatigue resistance, skid resistance, stability, impermeability, and flexibility.
But to make sure that these properties function, asphalt concrete mixture has to be properly designed, produced, and placed.
Different kinds of asphalt mixes are designed to serve various functions. For instance, the base asphalt mixes have entirely different functions in pavement structure than asphalt surface mixes.
Thus, both are produced differently. Various different kinds of asphalt concrete mixes are available to create unique structures.
For instance, the asphalt mix used in the construction of roads must withstand tough weather conditions and high traffic.
Thus, to cope with the applied pressure from vehicle wheels, it ought to be sufficiently stiff, and to resist cracking exerted by other pressures, it ought to possess adequate flexural strength.
Hot mix asphalt is the ideal mix for these high-traffic roads. Following are the three different kinds of asphalt mixes available
Cold Mix Asphalt.
Cold mix asphalt is widely used for roads with lighter vehicle traffic. Its production does not require heating as it uses a specific bitumen emulsion.
The emulsion breaks during compaction or mixing and coats the aggregate. Over time, this coating increases the asphalt’s strength.
Hot Mix Asphalt.
Hot mix asphalt is produced in extremely high temperatures between 150°C and 190°C.
Based on the usage, various mixtures can be made including porous asphalt, asphalt concrete for very thin layers, double-layered porous asphalt, and so on.
Warm Mix Asphalt.
Unlike hot mix asphalt, warm mix asphalt uses lesser energy and is produced in 20°C into 40°C of temperatures.
The temperature is low during the paving operations, ensuring safety for the working team and earlier opening of the road to be used.
Also, read: Building Estimation Step by Step In Excel Sheet
Ferro Cement Concrete.
Ferro cement concrete shouldn’t be confused with fiber concrete. Ferro cement consists of closely spaced wire-meshes that are impregnated with a rich mix of cement mortar.
Usually, 0.5 to 1.0 mm diameter steel wires are shaped into meshes. Mortar 1:2 to 1:3 using a water-cement ratio of 0.4 to 0.45 is poured to the form-work with fabricated steel by using layers of the wire mesh.
The steel content of the concrete will be as high as 300 to 500 kg/m3 of mortar. As the material consists of a large percentage of steel, it has high ductility and tensile strength.
The material was developed in 1940 by the Italian architect P. L. Nervi to build a large number of pleasing structural forms.
Fiber Reinforced Concrete (FRC).
It is that type of concrete where steel fibers 10 to 20 microns in diameter and 10 to 50 mm in length are used. Fiber increases resilience, tensile strength, flexibility, along with other qualities.
The fibers may be of different materials such as steel, polymer, glass, carbon, or even natural fibers such as coconut fiber.
Some types of fibers react with the cement; special care ought to be taken while using them. It has been used mostly as overlays for pavements in airports, bridges, and more than industrial floors.
Fiber-reinforced concrete may also be used in places where increased resistance to cracking is required.
Also, read: How to Find House Construction Cost
Fly Ash Concrete.
As much as 30 percent replacement of fine aggregates and 20 percent replacement of cement are reported. Fly ash improves workability from the fresh concrete and strength and durability within hardened concrete.
The particles of fly ash must be finer than of cement particles.
If the recycled glass is used as an aggregate in the concrete, this kind of concrete is called Glass Concrete.
They provide better thermal insulation and also have a great appealing look as compared to other types.
This type of concrete can also be called heavy-weight concrete. Within this concrete type, the density varies between 3000-4000 Kg/m3.
These kinds of concrete are prepared by using high density crushed rocks as coarse aggregates. One of such materials, Barytes is the most widely used material, that 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 kind of radiations.
High-Density Concrete Density: 3000 – 4000 Kg/m3
High Strength Concrete.
This concrete conforms to a particular standard but in no case, will be limited to strength. It has to be noted that all the high strength concrete could be a high-performance type.
However, not all high-performance concrete (HPC) are high strength concrete.
Standards that conform to This high-performance concrete are enlisted below:
• Environmental concerns
• Toughness and life term mechanical properties
• Long life and durability
• Heat of hydration
• Permeability and density factors
• Easy placement of the concrete
• Strength gain in early age
As its name suggests, insulating concrete form systems provide insulating properties such as the concrete walls of a structure below and above grade.
In residential construction, regular concrete foundation walls often require the installation of insulation after the forms are removed.
With ICFs, since the insulation remains in place, the insulation installation isn’t required. Insulated concrete forms are lightweight, and lots of systems are erected like toy building blocks making them easy to install.
Insulating concrete forms may be used for residential below-grade foundations and above-grade walls up to two stories. Engineering designs could be required for larger structures.
Concrete which has a density lesser than 1920kg/m3 will be categorized as lightweight concrete. Using lightweight aggregates in concrete design will give us lightweight aggregates.
Aggregates will be an important element that contributes to the density of the concrete. The examples of light-weight aggregates are the pumice, perlites, and scoria.
The light-weight concrete is applied for the protection of the steel structures and can also be used for the construction of the long-span bridge decks. These can also be used for the construction of the building blocks.
Lightweight Concrete Density: 1440 – 1920 Kg/m3
In this kind of concrete, lime can be used as a binding material with the aggregates. Before the invention of cement, the most used concrete was lime concrete.
The most important application of this product is on floors, domes as well as vaults. These unlike cement have lots of environmental and health benefits. These products are renewable and easily cleaned.
Normal Strength Concrete.
The concrete that’s obtained by mixing the fundamental ingredients cement, aggregate, and water will give us normal strength concrete.
The strength of this kind of concrete will be different from 10 MPa to 40MPa.
The normal strength concrete comes with an initial setting time of 30 to 90 minutes which is dependent on the cement properties and the weather conditions of the construction site.
Permeable concrete is ready in such a manner that the water could be passed inside. They have about 15 to 20% voids so that the water may pass inside.
They are used in those areas where stormwater issues persist.
Pervious concrete is another type of concrete used in the construction of roads and pavements. It’s designed to overcome the problems of storm-water runoff and replenishment of local watersheds.
Pervious concrete has the capability to absorb water rather than allowing it to puddle. This helps reduce hydroplaning, snow buildup, and tire spray, making the pavements safer for pedestrians and drivers.
This also helps reduce the need for storm sewers and curbing. It is the structure of the concrete which gives it the property of water absorption.
Like other kinds of concrete, pervious concrete is made of a mixture of cement, water, and coarse aggregates. However, the mix contains no sand, leading to a porous open-scale structure, allowing water to pass through easily.
Some kinds of porous pavement made from pervious concrete may allow 3-5 gallons of water to pass through per minute, making it an ideal structure to control stormwater drainage.
Pervious concrete pavements also offer improved filtration and the ideal amount of surface area to catch chemical pollutants and oil, which is not the case with traditional asphalt or concrete.
While previous concrete is ideal for pavements and low-volume applications like residential streets and parking lots, it is not appropriate for full-scale use on high-traffic roadways.
This is because its void structure does not have load-bearing properties that other kinds of concrete possess.
Plain or Ordinary Concrete.
The plain concrete will have no reinforcement within it. The main constituents are cement, aggregates, and water. The most commonly used mix design is 1:2:4 that’s the normal mix design.
The density of the plain or ordinary concrete will vary between 2200 and 2500 Kg/m3. The compressive strength is 200 to 500 kg/ cm2
These kinds of concrete are mainly utilized in the construction of the pavements along with the buildings, especially in areas where there is less demand for high tensile strength.
The durability given by these kinds of concrete is satisfactory to a high extent.
Plain or Ordinary Concrete.Density: 2200 – 2500 Kg/m3
In some mass concrete foundations, boulders of say 150 mm size up to 30% of the total quantity of concrete, are mixed in the wet concrete. This adds to economics and saves heat generation.
Such concretes are called plum concretes.
After at least two layers of wet concrete is completed, well-shaped and thoroughly washed, angular rock pieces using a maximum size of not more than 60% of a layer of pour thickness are placed in the concrete, keeping a distance of more than one-and-a-half times of the biggest size of aggregates in the concrete.
The bottom of the boulders should be embedded in the wet concrete to avoid voids at the bottom. Concreting is continued without stopping.
These rock pieces become an integral part of a concrete structure.
Polymerization is a process of conversion of monomers to polymers. In normal concrete, you need to have seen that micro-pores can’t be avoided.
The impregnation of monomer to those pores and subsequent polymerization is the technique that’s been developed recently to reduce the porosity of the concrete and to improve its strength and other properties.
The following are the four kinds of polymer concrete materials available at present.
Partially-impregnated and surface-coated polymer concrete.
This name is self-explanatory. These materials at present are mostly used in building construction only to improve durability or repairs works.
Polymer Impregnated Concrete (PIC).
This concrete type is ordinary-cured concrete, that can be dried in an oven, as well as the air at the open cells, is removed from the vacuum.
A low viscosity monomer is introduced into these spaces, which is then polymerized by the application of chemical heat or action or by using radiation.
Polymer Portland Cement Concrete (PPCC).
These kinds of concrete are made by mixing a monomer along with the mixing of aggregates, cement, and water.
However, the concrete obtained in this way isn’t as strong as the impregnated-type.
Polymer Concrete (PC).
In this kind of concrete, instead of cement, the polymer can be used using the aggregates. It’s not a true concrete as used in civil engineering terminology.
Most of the mega concrete projects are carried out through prestressed concrete units. This is a special technique where the bars or the tendons used in the concrete are stressed before the actual service load application.
Throughout the mixing and the placing of the concrete, these tensioned bars placed firmly and held from every end of the structural unit.
When the concrete sets and harden, the structural unit will be put in compression. This phenomenon of prestressing will make the lower section of the concrete member to be stronger against the tension.
The process of prestressing will require heavy equipment and labour skill (jacks and equipment such as tensioning). Therefore the prestressing units are made at the and assembled at site.
These are used in the application of bridges, heavily loaded structures, and roof with longer spans.
Various structural elements could be made and cast in the factory as per the specifications and bought into the site in the time of assembly.
Such concrete units are known as the precast concrete. The examples of precast concrete units are concrete blocks, the staircase units, precast walls and poles, concrete lintels, and many other elements.
These units have the advantage of acquiring speedy construction as the only assemblage is necessary. As the manufacturing is done on the site, quality is assured. The only precaution taken is for their transportation.
Usually, concrete is prepared by mixing different ingredients. But it’s also possible to pack some of the ingredients (coarse aggregate) from the form-work and then fill the pores using specially prepared cement-sand grout so that it will fill all the pores and form a concrete mass.
Pre-packed concrete is used in special situations like in which a large volume of concrete (such as a large machine block foundation) has to be concreted without construction joints.
One of the advantages of pre-packed concrete is that it has very little shrinkage.
Rapid Hardening Concrete.
As its name implies these concretes will acquire strength with few hours after its manufacture. Thus the formwork removal is made easy and thus the building construction is covered fastly.
These have a wide-spread application from the road repairs since they may be reused following few hours.
Ready Mix Concrete.
The concrete that mixes and bathed in a central mixing plant is known as ready-mix concrete. The mixed concrete is brought into the site with the help of a truck-mounted transit mixer.
This once reached in the site may be used directly without any further treatment. The ready-mix concrete is very precise and specialty concrete could be developed depending on the specification with utmost quality.
The manufacture of that concrete will require a centralized mixing plant. These plants will be located at an adjustable distance from the construction site. If the transportation is too long then it will result in setting of concrete.
Such issues of time delay are coped up with the use of retarding agents that delay the setting.
It’s also called RCC (Reinforced Cement Concrete). Within this concrete type, steel in various forms can be used as reinforcement to give very high tensile strength.
In fact, it is due to 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 bars, sticks, meshes, and all conceivable shapes. Every care is taken to ensure the maximum bond between the reinforcement and the concrete through the setting and hardening process.
Therefore, the resulting material (RCC) is capable of bearing all kinds of stress in any type of construction. RCC is the most important concrete type.
Stamped concrete is an architectural concrete where realistic patterns similar to natural stones, granites, and tiles can be obtained by placing an impression of professional stamping pads.
This stamping is performed on the concrete if it’s in its plastic condition. Different coloring stains and texture work will finally give a finish that’s very like costlier natural stones.
A high aesthetic look can be obtained from a stamped finish economically. This can be used in the construction of driveways, interior floors, and patios.
The concrete mix when placed will compact with its own weight is regarded as self-compacting concrete. No vibration has to be provided for the same separately.
This mix has higher workability. The slump value will be between 650 and 750. This concrete due to its higher workability can also be known as flowing concrete.
The areas where there is thick reinforcement, self-compacting concrete works best.
Shotcrete is a concrete prepared in the same manner as ordinary, however, the difference is that they are placed differently.
They’re placed with the help of higher air pressure through nozzles. The benefit of this technique is that the compaction and placing of concrete will be done simultaneously.
Silica Fume Concrete.
Silica fume is a byproduct of silica that’s very finely divided into the industry. The concrete where silica fume can be used is known as “silica fume concrete”.
The typical concrete using a normal water-cement ratio always has micro-pores, which limits the strength of regular concrete.
Silica fumes consist of very fine particles (actually, 6 times finer than of cement particles). Hence, if it is added to the concrete mix, the minute pore spaces can be reduced, resulting in high-strength concrete.
Silica fume can be a pozzolana which will contribute to the strength. Therefore, silica fume, along with super- plasticizers is a necessary component of high-performance and high-strength concrete.
Smart concrete technology offers an alternative method for monitoring the health of reinforced concrete structures.
It works by adding a small quantity of short carbon fiber to concrete using a conventional concrete mixer that modifies the electrical resistance of the concrete in response to stress or strain.
This may be used to monitor stress or strain from concrete structures, identifying potential problems before the concrete fails.
Smart concrete is capable of sensing very small structural flaws and hence finds application in checking the internal condition of constructions, particularly after an earthquake.
Smart concrete technology has undergone extensive laboratory testing, however, is yet to hit the market.
Vacuum concrete in the form of concrete where the excess water has been removed to improve concrete strength. All the water used for mixing isn’t required for hydration so it’s removed before hardening takes place.
To remove the water, vacuum pumps containing vacuum mats are generally used. Not only is the final strength of this vacuum concrete improved by 25%, but its stiffening pace also improves such that the form-works could be removed within 30 minutes of casting even on high columns. This allows frequent reuse of forms, making it extremely economical.
Vacuum concrete is characterized by higher density and increased bond strength. It can also be used for resurfacing old surfaces since it bonds well with old concrete.
Vacuum concrete is ideal for structures that frequently subject to flowing water at high velocity. This is because the uppermost 1/16 inch of its surface is highly resistant to abrasion and the whole surface is usually free of pitting.