Both portland and blended cements are hydraulic cements, that is, they react chemically with water and can do so while under water. There are several types of hydraulic cement, each of which lends itself to particular uses.

Types of portland cement are:

• Type I, for general use applications

• Type II, for use when concrete will be exposed to moderate sulfate conditions

• Type III, for use in applications requiring high early strength

• Type V, for use when concrete will be exposed to more severe sulfate conditions

Portland cements conform to specification ASTM C150.

Cement Type          Description
Type I                      Normal
Type II                     Moderate Sulfate Resistance               
Type III                    High Early Strength
Type V                     High Sulfate Resistance

– Type I—The standard product that has long been in use with no limitation on the proportions of the major oxides (CaO, SiO2, Al2O3, Fe2O3), also referred to as “ordinary portland cement.”

– Type II—This cement possesses moderate resistance to sulfate attack because of certain limitations on composition. Sometimes called moderate-heat cement, it is intermediate between Type I and the low-heat Type IV cement. If moderate heat of hydration is desired, however, the optional limit on heat of hydration should be invoked when specifying or ordering.

– Type III—High-early-strength portland cement is often produced by grinding Type I clinker finer or by altering the chemical composition of the cement.

– Type V—Sulfate-resisting portland cement with appropriate limits on composition.

Blended cements are mixtures of portland cement and other materials like limestone, blast-furnace slag, or pozzolans (for example, fly ash, silica fume, or natural pozzolans). Blended cements have a lower carbon footprint than portland cements and therefore will reduce concrete’s carbon footprint and can enhance durability.

Types of blended cement include:

• Type IL: Portland-limestone cement (PLC)

• Type IP: Portland-pozzolan cement

• Type IS: Portland blast-furnace slag cement

• Type IT: Ternary blended cement

Blended cements conform to specification ASTMC595. All of these base cement types are suitable for general concrete applications, and special properties like moderate or high sulfate resistance can be verified through testing. When special properties are applicable, additional descriptors are appended the type designation. For example, Type IL(MS) indicates a moderately sulfate resistant portland-limestone cement.