What is Portland Cement classified as?

Portland Cement is classified as a hydraulic cement, which means it can set and harden when mixed with water. It is produced from a finely ground mixture of limestone and clay that is heated at high temperatures in a kiln. This process creates clinker, which is then ground to a fine powder to create Portland Cement. The term "hydraulic" indicates that the cement can react with water and gain strength, even under water, making it suitable for various construction applications including structural concrete and masonry. This quality is essential in construction scenarios, especially in structural collapse situations, where materials must provide strength and durability under challenging conditions.

The other choices do not accurately describe Portland Cement: it is not a composite material, as it does not consist of two or more distinct materials combined to create properties that are superior to the individual elements. It also does not fit the definition of a non-hydraulic binder since those types require air to harden and would not perform the same way when exposed to moisture. Lastly, it is not a type of aggregate; aggregates are inert materials like sand or gravel mixed with cement and water to create concrete, while Portland Cement itself is the binding agent in concrete formation.