What is Concrete?–Types of Concrete

Concrete can be easily prepared and fabricated into a variety of shapes and structural systems. Its great simplicity stems from the fact that its constituents are ubiquitous and can be found almost anywhere on the planet. Because of its ubiquity, functionality, and flexibility, it has become the world’s most popular and widely used construction material.

The materials concrete and cement are frequently confused. Cement is one of many constituents of concrete, acting as a glue to hold the other materials together. Concrete is made by combining cement, supplementary cementitious materials, water, fine aggregate (sand/crushed rock fines), coarse aggregate (gravel or crushed rock), with or without admixtures, reinforcement, fibers, or pigments, and fine aggregate (gravel or crushed rock).

The ingredients are proportioned and engineered to produce concrete with a specific strength and durability, ensuring that it is ‘fit for purpose’ for the job at hand. It can be manufactured as precast products or as ready-mixed concrete delivered in the familiar rotating concrete lorry.

Concrete can be obtained from literally thousands of locations throughout the United Kingdom. One of the major sustainability benefits of concrete is that it is almost entirely sourced within the UK, with an average delivery distance of 46km for all concrete.

Concrete is a heterogeneous and composite mass consisting of cement, fine aggregates, coarse aggregates, and water.

As technology advances, it becomes clear that standard conventional concrete, which is used in all aspects of construction, has several drawbacks. Some of the defects may include low tensile strength, a very heavy self-weight of concrete, a delay in hardening due to a lack of suitable atmospheric conditions, freezing and thawing in cold weather, shrinkage, and bleeding due to the porous nature of concrete, and many others.

So, with the help of technology, efforts are made to strengthen ordinary conventional concrete in all aspects and to advance the world’s concrete construction to a new high.

These efforts resulted in the development of various types of concrete to meet our needs. This could be referred to as an improved version of conventional concrete.

Types of Concrete

Light Weight Concrete

One of the major disadvantages of ordinary conventional concrete is its extremely high self-weight, which ranges between 2300 and 2500 kg/cubic meter. As a result, efforts were made to reduce concrete’s self-weight.

Lightweight Concrete, as the name implies, provides a very lightweight concrete with a density of 800-1300 kg/cubic meter.

Concrete’s lightweight property can be achieved through three methods, which are as follows:

• Lightweight aggregates are used.
• By leaving out the sand from the aggregate (known as no-fines concrete)
• By incorporating air bubbles into the mortar (known as Aerated Concrete or Foam Concrete)

The most common method is to use lightweight aggregates instead of traditional mineral aggregates. Pumice, Diatomite, Scoria, Volcanic dust, Cinders, Rice Husk, and other lightweight aggregates are examples.

Advantages of Lightweight Concrete:

• The main advantage of low-weight concrete is its low density, which reduces dead loads and thus increases the progress of the building while lowering handling and haulage costs.
• Another advantage of low-weight concrete is its low thermal conductivity, which can be achieved by decreasing density.
• Low-weight concrete is to be used in the place of weak soils and tall structures, resulting in significant savings if the floors and walls are cast with low-weight concrete.

Heavy Duty Concrete

High-Density Concrete is another name for this type of concrete. As previously stated, low-weight concrete is lighter than standard conventional concrete. Similarly, the weight of High-Density Concrete is significantly greater than that of standard conventional concrete. The weight of High-Density Concrete is approximately 3360-3840 kg/cubic meter, which can be increased to approximately 5280 kg/cubic meter by the addition of iron as both fine and coarse aggregates.

Advantages of Heavy Concrete:

Radiation shields are typically built with high-density concrete. Because the nuclear energy industry generates a large amount of penetrating radiation and radioactive materials as a result of various nuclear reactors, particle accelerators, and so on, very dense concrete is required to protect personnel involved in such sectors from various biological hazards. Heavyweight concrete serves the purpose admirably.

Another advantage of using high-density concrete is its high modulus of elasticity and low thermal expansion.

Concrete Reinforced with Fibers

Standard Conventional concrete has a very low tensile strength, limited ductility, and little crack resistance. Internal microcracks are inherently present in concrete, and their propagation causes the material’s poor tensile strength, eventually leading to brittle fracture.

As a result, an attempt has been made to improve the tensile properties of concrete by increasing its inherent tensile strength. Experiments revealed that adding closely spaced, uniformly dispersed fibers to concrete would act as a crack arrester and significantly improve the tensile properties of the material. Fibre Reinforced Concrete is the name given to this type of concrete.

Steel fibers, polypropylene, nylon, asbestos, coral, glass, and carbon are some examples of fibers that can be used in the production of Fibre Reinforced Concrete. Steel fiber is the most commonly used fiber. These can be found or flat in shape, with a diameter ranging from 0.25 to 0.75mm.

Fibre Reinforced Concrete Benefits:

• Fibre Reinforced Concrete is widely used in bridge decks, artificial pavements, roads, and other applications where the tensile strength of concrete is critical.
• Increased tensile strength has a significant impact on several other important factors of concrete, which can also be used in different atmospheric conditions.

White Concrete

As previously stated, concrete is a homogeneous mixture of cement, fine and coarse aggregates, and water, with cement playing the most important role as the material that drives the properties of the concrete to be imparted. Grey Portland cement is used in the production of Standard Conventional Concrete. White Cement Concrete is manufactured concrete that uses white Portland cement instead of grey Portland cement.

Because of the following factors, white Portland cement is significantly more expensive than ordinary grey Portland cement:

• White Portland cement consumes approximately 40% more energy than ordinary Portland cement.
• To increase the whiteness of the cement, a large amount of iron and manganese are added during the manufacturing process, making the cement more expensive in nature. As a result, the additional materials raise the price.
• Special precautions must be taken when producing white cement, which raises the overall manufacturing cost of the cement.

White cement is approximately four times more expensive than ordinary Portland cement, and its compressive strength is lower than that of OPC.

Advantages of White Concrete

• One of the most significant advantages white concrete provides is its pleasing appearance from an architectural and aesthetic standpoint, which is why it is widely used in modern decorative works, both interior and exterior surfaces, due to its whiteness.
• Because of the finer grinding of white cement, white concrete has a neat and smooth surface. As a result, white concrete is mostly used in the production of precast members.

Polymer Concrete

The concrete has already been discovered to be porous. The porosity is caused by the presence of air and water voids, as well as the inherent porosity of the gel. The reduction of porosity improves the strength of concrete significantly.

As a result, efforts have been made to reduce the porous behavior of concrete. Some of the methods that can be used include vibration and pressure application spinning, but none of them help to reduce the water voids and inherent porosity of gel, which is estimated to be around 28%. Experiments revealed that the use of monomers in concrete and polymerization effectively reduces water voids in concrete. Polymer concrete is the name given to this type of concrete.

There are four types of polymer concrete that are commonly used:

• Polymer-Infused Concrete (PIC)
• Concrete with Polymer Cement (PCC)
• Polymer Concrete (PC) is a surface-coated polymer concrete that has been partially impregnated.

The Benefits of Polymer Concrete:

• The main benefit of polymer concrete is that it has no water voids, which can be attributed to the increased strength of concrete.
• Polymer concrete has a high tensile strength and toughness.