Portland cement is an incredibly common material. It’s also the basic ingredient of concrete, which is formed when portland cement creates a paste with water that hardens after binding with sand and rock.
First discovered by Joseph Aspdin in Leeds, England in the early Nineteenth Century, portland cement is produced by heating lime, iron, silica, and alumina to extreme temperatures (2,500 to 2,800 degrees Fahrenheit) in a rotating kiln. The kiln’s stony residue, or clinker, is ground into a fine powder, otherwise known as cement.
The cement produced is differentiated by the distribution of these materials in its chemical composition, as well as the finishing products. The distinct types of portland cement are defined through ASTM C150-20: Standard Specification for Portland Cement, which distinguishes them by purpose.
The standard types of portland cement are:
- Type I – for general purpose
- Type IA – same as Type I, but when air entrainment is desired
- Type II – for moderate sulfate resistance
- Type IIA – same as Type II, but when air entrainment is desired
- Type II(MH) – much like Type II, but when moderate heat of hydration is desired
- Type II(MH)A – same as Type II(MH), but when air entrainment is desired
- Type III – for high early strength
- Type IIIA — same as Type III, but when air entrainment is desired
- Type IV – for low heat of hydration
- Type V – for high sulfate resistance
For maintaining a level of consistency between cement-producing plants, standards are key. In addition, documents like ASTM C150-20 contain information useful to others using portland concrete, as each type serves a different function. While Type I is used for general construction, including buildings, bridges, and pavements, each other type fits a specialized purpose.
In addition to defining portland cement types, ASTM C150-20 details ingredients, chemical composition, physical properties, and sampling and testing methods.