What Is Cement | Definition, History, Types & Application

What Is Cement?

Cement is a fine powder made from a combination of limestone, clay, and other minerals. It is a binding material used in construction to bind other materials such as sand, gravel, and water to create concrete, mortar, and other building materials.

Cement is known for its ability to harden and set when mixed with water, creating a solid structure that can support heavy loads and withstand harsh weather conditions. It is a critical component of many construction projects, including buildings, bridges, roads, and dams.

Cement is available in different types, each with unique properties that make them suitable for specific applications.

These types include Portland cement, which is the most common type of cement, as well as white cement, rapid hardening cement, and low-heat cement.

The use of cement has revolutionized the construction industry, providing builders and engineers with a versatile and durable material that can withstand the test of time.

Application of Cement

Cement is mostly used as mortar and concrete, in which cement is mixed with aggregates to form a specific grade of concrete.

Mortar is basically a mixture of cement and sand (crushed stone) having a size of less than 5mm i.e 0.2 inches.

On the other hand, Concrete is also a mixture of aggregates and cement, but both coarse and fine aggregates are present in proportions.

Mortars made of cement are used for binding bricks, blocks, and stone in masonry walls or as surface renderings.

Concrete has a wide range of applications in construction. Mixtures of soil with portland cement are used for the construction of the base layer of roads.

Portland cement has applications in the manufacture of bricks, tiles, shingles, pipes, beams, railroad ties, and various extruded construction operations.

History of Cement

As historical research says that people of that time know about the binding property of lime. In the past, people have been using lime for making brick bonds and other work.

The Roman Empire used lime concretes and also developed the pozzolanic cement material of lime and certain volcanic earth.

This concrete and lime mortar continued to be used up to the Middle Ages.

An English engineer Joseph Aspdin from Leeds city – England 1824, successfully produced a powder made from the calcined mixture of limestone and clay.

After that, he patented the material, and the name was given “Portland Cement”, because when it hardened it produced a material similar to stones from the quarries near Portland Island in the UK.nWith time the process of manufacturing cement has changed but the formula and material remain the same.

Later, Isaac Charles Johnson in 1845 had an experiment. he burnt a mixture of clay and chalk till the tinkering stage to make better cement and established factories in 1851

In 1877, The German standard specification for Portland cement was drawn. In 1904, The British standard specification was first drawn, and moreover, The first ASTM specification was issued in 1904.

In India, it was first manufactured in 1904 near Madras, by South India Industrial Ltd. But this venture failed.

The cement manufacturing unit in Turkey was first started in Darica Cement Factory in 1913 with a production capacity of 20,000 tons/year.

Raw Materials of Portland Cement

Calcareous rocks material (CaCO3 > 75% such as limestone, marl, chalk),

Argillaceous rocks material (CaCO3 < 40% such as clay and shale),

Argillocalcareous rocks material (40-75% CaCO3 such as clayey limestone, clayey marl).

Portland cement can be manufactured from any two groups above. This raw material must be used in the proper form and proportions of lime, silica, and alumina.

Manufacture of Cement

There are four stages in the manufacture of portland cement,

Crushing and Grinding
Blending the Materials
Burning
Grinding

Crushing and Grinding

Soft materials are first crushed, too in two stages. This Grinding can be done in a wet or dry state, that depends on the process which is in use.

However, for grinding in the dry state the raw materials are needed to be dried in cylindrical rotary dryers.

Soft materials are needed to be broken down through vigorous stirring with the water in wash mills, producing a fine slurry, which is later passed through the screens for removal of oversize particles.

Blending

The next step involved after crushing and grinding is blending the crushed raw materials. Initially, an approximation of the chemical composition required for a specific cement is obtained through selective quarrying and with control of the raw material fed in the process to the crushing and grinding plant.

In the dry process mixing of the materials in the silos is carried out by agitation and vigorous circulation which include compressed air.

While, in the wet process, the slurry tanks are needed to be stirred by the means of mechanical action, using compressed air or both used together.

Burning

Bottle kilns ate the traditional types of kilns followed by chamber kilns and then continuous shaft kilns were invented. The shaft kiln is used in many countries modern days but the dominant means of burning is the rotary kiln.

When the raw material is fed to the kiln at the upper end, it slowly moves down the kiln at the firing, end. The fuel used for firing is pulverized coal, oil, or natural gas.

The temperature at the firing end could be as equal as in the range of 1,350 to 1,550 °C or 2,460 to 2,820 °F, depending on the type of raw material being burned.

The burned product comes out from the kiln in the form of small nodules of clinker. These clinkers are then passed into coolers for cooling.

The colled clinker depending on its properties can be immediately ground into cement or stored in stockpiles for further use.

Grinding

The clinker and gypsum are ground to form a fine powder in mills similar to those used before for grinding the raw materials brought directly to mills.

Material properly grinned are passed further while the improperly grinned are again taken to grinding. Sometimes it is required to add a small amount of grinding aid to feed material. Finished cement is stored in bags and packages for distribution.

Tests on Cement

Various tests are performed on cement to know its properties, characteristics, and suitability for use. Some of the tests on cement are discussed below,

1. Fineness

The fineness of the cement can be tested using sieve analysis tests, however, these days more sophisticated methods are now largely used.

A commonly used method to obtain accurate results for both control of the grinding process and testing the finished cement measures the surface area per unit weight of the cement by analyzing the rate of air passage through a bed of cement.

However other methods for finding the fineness of cement depend on the principle of measuring the particle size distribution by the rate of sedimentation of the cement in kerosene or by elutriation in an airstream.

2. Soundness

After setting Cement, it should not undergo expansion more than appreciable limits, which could cause disruption of mortar or concrete. This occurrence shows the soundness of cement.

The soundness of cement is tested by subjecting the set cement to boiling in water or to high-pressurized steam for a certain period of time.

This test shows the presence of free magnesia or hard-burned free lime in cement.

3. Setting Time

The soundness of cement is tested by subjecting the set cement to boiling in water or to high-pressurized steam for a certain period of time.

This test shows the presence of free magnesia or hard-burned free lime in cement. along with its hardening are continuous processes, though two points are differentiated for test purposes.

The initial setting time of cement is the instance between the mixing of the cement with water and when the mix has lost plasticity, stiffening to a certain amount.

It roughly states the end of the period when the mix is still wet can be molded into a required shape. The final setting time of the cement can be defined as the point at which the cement has acquired a relatively sufficient firmness to resist a certain degree of pressure.

4. Strength

Cement has the capability to withstand compressive strength however, it is weak in tensile strength. Hence Reinforced Steel is induced in the cement to provide tensile property to concrete.

The American Society for Testing and Materials (ASTM) had specified the requirement of ratio 1:3 i.e. cement-sand mortar in case of tensile strength and compressive tests on that of 1:2.75 mortar.

The strength requirements of cement laid down by various countries in the world are not directly comparable because of the differences in test methods of each country.

Importance of Cement In Construction

Cement is a crucial ingredient in the construction industry, playing a vital role in the creation of infrastructure projects.

Its versatility, durability, and strength make it an essential material for building structures that can withstand harsh weather conditions and heavy loads.

Cement can be mixed with other materials to create concrete, which is one of the most widely used construction materials in the world.

Structures made from cement and concrete are known for their longevity, making them a cost-effective choice for long-term projects.

Cement is also a fire-resistant material that can help prevent the spread of fires in buildings. Additionally, advances in technology have led to the development of eco-friendly cements that have a lower carbon footprint, making them a sustainable choice for construction.

Overall, cement is a fundamental building block of the construction industry, providing the necessary structural support and stability for buildings, bridges, roads, and other infrastructure projects.

Its importance in the construction industry is likely to remain significant for many years to come.

Why Cement Is Popular Building Material

Cement is a popular building material for several reasons. Here are some of the main reasons why cement is widely used in the construction industry:

Versatility: Cement is a versatile material that can be used to create a wide range of structures, from buildings and bridges to roads and dams. It can be mixed with other materials, such as sand, gravel, and water, to create concrete, which is one of the most widely used construction materials in the world.
Durability: Cement is a highly durable material that can withstand harsh weather conditions, extreme temperatures, and heavy loads. Structures made from cement are known to last for many decades or even centuries, making it a cost-effective choice for long-term projects.
Strength: Cement is a strong and sturdy material that can support heavy loads and withstand high levels of stress. This makes it ideal for constructing large buildings and infrastructure projects.
Fire Resistance: Cement is a non-combustible material that does not burn, making it a popular choice for fire-resistant construction.
Availability: Cement is a widely available material that can be sourced locally in many parts of the world. This makes it a convenient and cost-effective choice for builders and construction companies.
Sustainability: Cement can be made from a variety of natural materials, such as limestone, clay, and shale. Additionally, advances in technology have allowed for the development of eco-friendly cements that have a lower carbon footprint.

Types of Cement In India

Ordinary Portland Cement (OPC)
Portland Pozzolana Cement (PPC)
Rapid Hardening Cement
Extra Rapid Hardening Cement
Quick Setting Cement
Low Heat Cement
Sulphate Resisting Cement
Portland Slag Cement (PSC)
High Alumina Cement
White Cement
Coloured Cement
Air Entraining Cement
Hydrophobic Cement
Masonry Cement
Expansive Cement
Oil Well Cement

Types of Cement In Europe

Classification as per Euro EN 197-1

CEM I (Portland cement)
CEM II (Portland-composite cement)
CEM III (Blast furnace cement)
CEM IV (Pozzolanic cement)
CEM V (Composite cement)

Types Available in the USA

Classification as per ASTM C150

Type I (Portland cement)
Type II (Sulphate Resisting Cement)
Type III (Rapid Hardening Cement)
Type IV (Portland Pozzolana Cement (PPC)
Type V (Hydrophobic Cement)

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What Is Cement | Definition, History, Types & Application

What Is Cement?

Application of Cement

History of Cement

Raw Materials of Portland Cement