**5.1 Portland cement**

Portland cement is the most common, low-cost, and widely used type of cement worldwide because its basic ingredients are inexpensive and readily available. It consists of four major components: tricalcium silicate, tricalcium aluminate, dicalcium silicate, and tetracalcium aluminoferrite.

For specialized objectives, such as durability and high early strength, several kinds of Portland cement are produced to fit distinct physical and chemical characteristics [31, 32].


*Characterizations of Cement and Modern Sustainable Concrete Incorporating Different Waste… DOI: http://dx.doi.org/10.5772/intechopen.100447*

oil, and another acid with a wetting agent such as aluminum powder, hydrogen peroxide, and so on results in the entrainment of extremely fine air bubbles in the concrete, which improves workability with a lower water–cement ratio, as well as improves frost-resistant characteristics.

• **Hydrophobic cement:** Hydrophobic cement is made from regular Portland cement clinker by grinding it with specific water repellent components such as oleic acid, stearic acid, or naphthenic acid. A water-resistant coating is formed over each cement particle, preventing water or moisture from the air from being absorbed by the cement. This film is broken during the regular hydration process and behaves just like ordinary Portland cement.

This cement has excellent resistance during transportation and long-term storage in severely moist climatic conditions.

• **Quick-setting cement:** This is cement that has the property of setting very quickly. This feature is obtained by decreasing the gypsum content during the clinker grinding process.

Quick-setting cement is used for concreting in static or flowing water, underwater construction, and rainy and cold weather conditions, or when work must be finished in a short period of time, like in places with higher temperatures where water evaporates easily.

The distinction between rapid hardening and quick-setting cement is that quick-setting cement sets faster. Simultaneously, the rate of strength growth is comparable to that of ordinary Portland cement, but quick hardening cement builds strength rapidly.
