Portland Cement: Composition and Types of Portland Cement

Portland Cement

The Portland cement was first manufactured by Joseph Aspdin from England who was a bricklayer. He took the license for Portland cement in 1824. Since then, continuous efforts were made on cement and discovered that improving chemical compositions in cement show different characteristics and properties.

Portland cement is the product obtained by pulverizing clinker, consisting of hydraulic calcium silicates to which some calcium sulfate has usually been provided as an inter ground addition.

When first made and used in the early 19th century in England, it was termed portland cement because its hydration product resembled a building stone from the Isle of Portland off the British coast. The specific gravity of portland cement particles is about 3.15.

Primary Compounds

There are four primary compounds in portland cement,

  • Tricalcium silicate 3CaO·SiO2 (C3S)
  • Dicalcium silicate 2CaO·SiO2 (C2S)
  • Tricalcium aluminate 3CaO·Al2O3 (C3A)
  • Tetracalcium aluminoferrite 4CaO·Al2O3Fe2O3 (C4AF)

In shortened symbols varying from the typical atomic symbols, these substances are specified as C3S, C2S, C3A, and C4AF, where C represents calcium oxide (lime), S for silica, A for alumina, and F for iron oxide.

Five types of portland cement are standardized in the USA by the American Society for Testing and Materials (ASTM). Ordinary (Type I), modified (Type II), high-early-strength (Type III), low-heat (Type IV), and sulfate-resistant (Type V).

All these five types of cement consist of 75% of calcium silicate-based components with varying developing periods or setting agent components usually gypsum.

Type I Cement

This type of cement is also called ordinary Portland cement. This cement is usually used for almost every construction activity and to construct structures that do not require and need specific significant properties.

It is mostly used in constructions of all types of commercial, residential, and industrial buildings, floors, sidewalks, storage tanks, brickwork, bridges and so on which do not have a specific issue that needs to be resolved such as sulfate hazard or risk, air entraining, heat of hydration or freezing condition.

Type-I-Cement

Type II Cement

This type of Portland cement a bit change with Type I or the ordinary cement by the methods of minor cover opposing modest sulfate outbreak. This type of cement is generally used in structures where the soil or groundwaters have considerable sulfate level which is more than the normal where ordinary cement could still be used. Even so, this level is minimized not to rise above extreme quantity which might result in major damages to the concrete structure.
This cement usually consists of not more than 8% of tricalcium aluminates the element which is responsible for the starting settling period and strength. This type of cement generates a slower heat level than type I cement and might also be utilized for concrete specifically exposed to seawater. Although the sulfates in the sea might hurt the concrete, the presence of chlorides limits it. It is usually used in making very thick bridge support and dams.

Type III Cement

Type III Portland cement is a type of cement utilized for constructions or structures which require provide an early strength usually a week or much less. The physical and chemical properties of this cement are rather comparable to type I cement however vary mainly in their powder grain size. This cement is used when early strength and curing time is reduced to its least feasible option.

Type-III-Cement

Type IV Cement

This type of cement is created to reduce the level and the amount of heat produced from hydration which also indicates that the strength of the concrete is developed at a slower level than those of type I cements. This type of cement is generally used in the construction of huge concrete structures such as dams (where the temperature might) rise to decrease hardening.

This slow heat rate produced throughout hydration restricts the concrete elements’ internal temperature level which could cause irregular development which might result in cracking and damages at the beginning. This type of cement is rarely used today as its particular properties could be attained by mixed cement.

Type-IV-Cement

Type V Cement

Type V cements are primarily made with advanced anti-sulfate properties than type II cement. This cement is used in making concrete that is exposed or directly in contact with harsh sulfate concentration or where soil and groundwater possessed intense sulfate risk.

Type V cement has a slower strength growth rate than type I cement and its high sulfate resistance is caused by its reduced tricalcium aluminates content which is not going beyond 5%. However, just like the other Portland cements, type V cement is not resistant to acid strikes or any other highly harsh substances.

Air-entraining Portland Cements

Air-entraining cements specs represent cement types I, II, and III compositions except for its air-entraining ingredients which are initially included during its production process when it’s still clinker nodes. These cements are designed with improved cold resistance. With these cements, concrete would certainly have well-distributed and completely apart air bubbles. Generally, air-entraining cements are available just for areas with winter or snow weather.

Air-entraining Portland Cements