Cement is one of the basic materials in construction. However, it’s an essential item for development in the construction industry. Cement is classified into various categories based on its composition and specific end uses. Cement is classified as either portland, blended, or specialty cement. The major U.S. companies that manufacture cement are CRH plc (CRH), Cemex, SAB de CV (CX), Eagle Materials Inc. (EXP), and James Hardie Industries SE (JHX). Investors can access the cement industry through the Vanguard FTSE Emerging Markets ETF (VWO).
Portland cement (or OPC) is the most common type of cement. It’s a basic ingredient of concrete. Portland cement is a mixture of limestone and clay. It’s ground and burnt at a very high temperature to form clinker. The clinker is ground into a fine powder. Gypsum—up to 5%—is added to the powder to form portland cement. The essential components of portland cement are lime, silica, alumina, and iron oxide. There are different types of portland cement. Each kind of portland cement has a different chemical composition. However, the manufacturing process is the same for each kind of portland cement.
In order to produce blended cement, certain natural or man-made compounds such as pozzolona, slag, and sandstone are mixed with portland cement clinker and ground together. Blended cement is more suitable for certain applications compared to portland cement. Blended cement is also called low-heat cement because it generates lesser heat during hydration compared to OPC. This cement is used for large concrete works such as dams and piers. Blended cement minimizes the risk of developing contraction cracks because of the lower hydration heat.
Specialty cement has several unique properties. It’s used in specific applications like urgent repairs and super high strength applications.
Please continue reading the next part of the series to learn how cement is prepared.