What is Portland-pozzolan cement primarily composed of?

Portland-pozzolan cement is primarily composed of Portland cement and pozzolans, which are materials that, when mixed with lime, have cementitious properties. Pozzolans can include natural or artificial materials that react with calcium hydroxide at room temperature to form compounds possessing cementitious properties.

The inclusion of pozzolans in the cement mix enhances various properties of concrete, such as increased durability, improved workability, and reduced permeability. By utilizing pozzolans, this type of cement can also reduce the overall carbon footprint of concrete production, offering a more environmentally friendly option compared to conventional Portland cement alone.

In contrast to the other options, fly ash and silica fume are specific types of pozzolans. While they may be present in other types of blended cements, they do not encompass the complete definition of Portland-pozzolan cement, which is characterized by its combination with any suitable pozzolan, not just specific types. Additionally, limestone, while used in other in the context of cement making, does not classify as a pozzolan and is not part of Portland-pozzolan cement’s essential composition.