How does limestone make cement

The great pyramids of Egypt, among many other landmarks, are constructed of limestone. It was also very popular in the Middle Ages, due to its hardness, durability, and availability.

Many medieval churches and other structures still standing are made of limestone. Limestone is also used as a pigment in toothpaste. In addition to the value of limestone slabs quarried for building materials, limestone is also used in cement.

A discussion about cement requires a distinction between cement and concrete: although the two terms are often used interchangeably. The cement clinker emerges from the kiln, is cooled, and then finely ground to produce the powder we know as cement. The Canadian cement and concrete industry is pursuing a variety of innovative measures to further reduce its carbon footprint.

Cement powder. Concrete's basic ingredients: cement mixed with sand, gravel, and water. The labs also analyze and test the finished product to ensure that it complies with all industry specifications.

The most common way to manufacture portland cement is through a dry method. The first step is to quarry the principal raw materials, mainly limestone, clay, and other materials. After quarrying the rock is crushed. This involves several stages. The first crushing reduces the rock to a maximum size of about 6 inches.

The rock then goes to secondary crushers or hammer mills for reduction to about 3 inches or smaller. The crushed rock is combined with other ingredients such as iron ore or fly ash and ground, mixed, and fed to a cement kiln. The cement kiln heats all the ingredients to about 2, degrees Fahrenheit in huge cylindrical steel rotary kilns lined with special firebrick. Kilns are frequently as much as 12 feet in diameter—large enough to accommodate an automobile and longer in many instances than the height of a story building.

The large kilns are mounted with the axis inclined slightly from the horizontal.