What is Cement?

Cement is one of the most common and important building materials. It is a very fine powder made of crushed minerals, which absorbs water and acts as a binder to hold the concrete together. While there are many types of cement, Portland cement is the most commonly used cement, and is an ingredient in concrete, mortar, and plasters. It can be mixed with water and aggregates to form concrete or mortar or mixed with sand, gravel, and water to make asphalt concrete or Portland cement concrete.

Portland cement accounts for more than 95% of all cement produced. Portland cements are hydraulic cements that harden in the presence of water. They contain one or more of the forms of calcium sulfate as an interground addition. Most often it is gypsum (CaSO4·2H2O), but it can also be anhydrite (CaSO4). The name “Portland” comes from its resemblance to Portland stone when hardened. Portland cements are used for structures exposed to severe weather conditions such as bridges, dams, highways, parking structures and buildings.

Cement was discovered by the Romans who found that adding volcanic ash to lime created a much stronger material. And this cement was used to construct the magnificent Roman structures that still amaze us today.

The Romans didn’t know it then, but there is a chemical reaction that occurs when the volcanic ash and lime are mixed together. The calcium oxide in the lime reacts with the silicon oxide in the volcanic ash to create calcium silicate. The Roman cement is known as hydraulic cement because water will cause it to harden and set.

But how does modern-day Portland Cement differ from ancient Roman Cement? Portland cement is made from limestone and clay mixed together, and then heated at a very high temperature in a kiln. The composition of this mixture varies depending on the desired outcome of the Portland Cement. Once it has been heated and cooled, small amounts of gypsum are added to regulate how quickly or slowly the cement sets.

This is what makes Portland Cement different from all other cements – it can be adjusted to set in any amount of time between a few hours and a few months, which means that concrete can be poured for any type of construction project and weather conditions.

Cement is one of the most widely used materials in construction. It is used as an ingredient in concrete, mortar, render and screeds. The cement itself is a fine grey powder which when mixed with water, sand and gravel becomes a hard solid mass.

The cement itself is produced by burning a mixture of limestone and clay until it forms a clinker. This is then ground down to a fine powder to produce the finished cement.

Cement is produced by heating together a mixture of limestone and clay (or shale) in large rotating kilns at temperatures of around 1400 degrees centigrade. The resulting clinker is then cooled, ground to a very fine powder and mixed with small quantities of gypsum to produce the final product or Portland cement.

Portland cement comes in five standard types:

* Ordinary Portland Cement (OPC)

* Rapid Hardening Cement (RHC)

* Extra Rapid Hardening Cement (ERHC)

* Sulphate Resisting Cement (SRC)

* Low Heat Cement (LHC)

While cement is the key ingredient of concrete, which in turn forms the building blocks of our cities, roads and infrastructure. Cement is just one ingredient in the mixture, but it is the most chemically active ingredient and crucial to the quality and durability of the concrete.

Cement is a fine-grained compound that turns into a solid when mixed with water. It is most commonly used to bind together bricks or stones. Cement is used on its own or with other materials to form mortar or concrete. Cement manufacturing involves a combination of raw materials that are heated at high temperatures to produce a product called clinker, which when ground with gypsum produces cement.

Cement is a substance made by heating limestone (calcium carbonate) with other materials (such as clay) until it almost melts and the resulting mixture is finely ground into the grey powder we all know as cement. There are a number of different types of cement, including ordinary Portland cement, white Portland cement, rapid hardening cement and low heat Portland cement. All these products are made from a mixture of limestone, clay and/or shale.

Portland cement is a basic ingredient of concrete, mortar and most non-speciality grout. The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Concrete was first used by the Romans who found this construction material very useful indeed!

Historically, cements used in construction were often lime based, such as lime putty. The use of Portland cement quickly replaced lime based cements and its popularity can be traced back to Joseph Aspdin’s patent in 1824. Portland cement has been the most common form of cement ever since and is used to make concrete.

Portland cement is a grey powder that hardens when mixed with water. It can be mixed with aggregates (sand and gravel) to form mortar or concrete. It is used as a binding agent in building and civil engineering projects. The following steps are involved when making Portland cement:

The raw materials used in the production of Portland cement include limestone, sand and clay or shale. They are first crushed to a fine powder and then blended in the correct proportions to create the final product.

In a rotary kiln, the blended raw materials are heated to around 1,500°C which produces a chemical reaction known as sintering that bonds the components together to make clinker. The clinker is cooled, ground down with gypsum to create Portland cement which takes approximately 10-25 minutes to set depending on its strength i.e. rapid hardening or slow setting

White portland cement is a type of special cements, which contains white materials like high-purity alumina, pure magnesium oxide and pure calcium oxide. White portland cement is generally a mixture of white clinker and gypsum. Its properties are similar to that of grey portland cement, but its color is white. White portland cement has tons of uses in the construction industry. It’s commonly used in architectural works because it makes the construction look more attractive. White portland cement also has excellent decorative effects, especially when used with colored aggregates.

White portland cements are made by adding iron oxide or by burning white raw materials such as limestone or chalk at temperatures over 2700C. Because the ingredients used in making white cement are very expensive, the price of this type of cement is usually much higher than that of gray portland cement.

White portland cements are commonly used for exterior masonry finishes, terrazzo flooring and for exposed aggregate concrete for swimming pools, sidewalks and driveways.