Types of Cement available in the market and how to choose between them

Cement is a major constituent of any building. It also forms a high percentage of overall costs. Given its significance, it is important to know the different types of cement available in the market and how to choose between them.

There are three types of cement available in the market; Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC), and Portland Slag Cement (PSC). All three of them can be used to construct buildings, big or small. PPC and PSC are also known as blended cement since fly ash and slag are mixed with cement respectively.

In many regions, it is possible that only one type of cement is widely available. This is because the raw materials required to manufacture each variant are available freely and hence cheaper in particular regions. For example, fly ash from steel plants is available in higher quantities. Fly ash is one of the main ingredients in PSC. Hence, PSC is more freely available. In the same way, some region has many thermal power plants from where fly ash is easily available for blending with cement in the manufacture of PPC.

PPC and PSC are more environments friendly than OPC since they use waste material as input. PPC typically uses fly ash (waste generated by coal-based power plants) and PSC uses slag generated in the blast furnace of steel plants.

Ordinary Portland Cement (OPC)OPC is a product obtained by intimately mixing together calcareous (limestone, chalk, marl, etc.) and argillaceous (clay, shale, etc.) materials, with or without other materials containing silica, alumina, or iron oxide, burning them at a high temperature, and grinding the resulting intermediate product, clinker with gypsum. After burning, no material other than gypsum is added. This is the ‘original’ cement, made using the traditional process without blending it with any other modern materials. OPC is suited for all buildings that are not exposed to extreme moisture, salt, and chemical attacks.

Typically, OPC is available in two grades in the market, 43 and 53. The grade indicates the compressive strength of the cement in N/mm2 at 28 days. Depending on the structural design, any one of them can be used for construction. The words Ordinary Portland Cement is written on all OPC cement bags.

Portland Pozzolana Cement (PPC)PPC is manufactured either by grinding intimately together Portland cement clinker, gypsum, and a Pozzolana such as fly ash or by intimately and uniformly blending Portland cement and fine Pozzolana.

The difference between OPC and PPC is due to the addition of Pozzolana in the latter. The Pozzolana is a siliceous or siliceous and aluminous material. Fly ash sourced from thermal power plants is the most common source of Pozzolana. 15 to 35% by weight of cement can be added as fly ash. In OPC, moisture reacts with calcium hydroxide in concrete. This reduces the strength of concrete. In PPC, moisture reacts with fly ash to form compounds that provide additional strength. PPC manufacturers indicate the following benefits of PPC.Better impermeability; higher resistance to water.Lower heat of hydration; easier to work with on-site.Improved resistance to chemicals.Due to the presence of fly ash, PPC is usually darker in color than OPC. The words Portland Pozzolana Cement is written on all PPC cement bags.

Fly ash is usually cheaper to procure if the source is near to the cement plant. However, due to its better properties, PPC usually sells at a premium to OPC in the market.

Portland Slag Cement (PSC)PSC is an intimately ground mixture of Portland cement clinker and granulated blast-furnace slag, either inter-ground or ground separately and blended together. Blast furnace slag can be obtained only from integrated steel plants. PSC can contain from 35% to 70% in the form of slag by weight of cement. PSC has the following advantages over OPC.-Improved workability-Higher-strength-Better chemical resistance-Better resistanceDue to the presence of slag, PSC is usually lighter in color than OPC. The words Portland Slag Cement is written on all PSC cement bags. Further, due to its improved properties, PSC is generally priced higher than OPC in the market.

In sum, if PPC is available in the market at a price close or comparable to OPC, it can be preferred over OPC. PPC can also be preferred in case the building is exposed to high moisture or chemical attack. PSC can be preferred in applications where a building is exposed to high moisture, salt (chloride or sulfate), or chemical attack. For example, marine structures, sewage treatment-related buildings, etc.

About the Author:Tansen Cement is one of the leading Cement Factory in Nepal, established with a vision to provide quality cement in the Nepalese market. Manufactured by Palpa Cement Industries Pvt. Ltd., Tansen Cement is made with the highest quality raw materials, and cutting edge technology ensures that only the best quality cement reaches the consumer. We provide quality of Cement in Nepal.

Tansen Cement is one of the leading Cement Factory in Nepal, established with a vision to provide quality cement in the Nepalese market.