What Is Cement Made Of?

Posted on January 15, 2019

It makes up the foundations to structures, keeps skyscrapers standing and hardens to immense strengths within a matter of days. It’s been used since Roman times to create solid roadways, seal water storage and adhere huge blocks together. What are we talking about? Cement, which is the primary binding compound in concrete. But what is cement made of? What’s the process that turns these natural materials into a solid matrix that binds the world together? Here’s a quick look at how it works:

What Is Cement Made Of?

  • Cement is manufactured from a closely controlled chemical combination of calcium, silicon, aluminum, iron ore and other ingredients, including fly ash, small amounts of gypsum, limestone, and clay.
  • The tools used in the manufacture of Portland cement include a cement kiln, rotary kilns, sieves capable of holding water and many other pieces of machinery in the process.
  • The exact cement manufacturing process varies based on the type of cement that is being created, but generally speaking, in the cement plant, the raw materials are crushed and ground into a fine powder that can pass through a sieve capable of holding water.
  • At the cement plant, the powdered materials are then fed into the kiln, heated to extremely high temperatures around 2,700 degrees Fahrenheit and then churned in huge cylindrical rotary kilns to keep the materials mixing while they are hot.
  • A rotary cement kiln is a huge piece of equipment, up to 12 feet in diameter and over 400 feet long. It has a huge cylinder of steel inside that is lined with a special type of firebrick and it’s mounted on an axis that is inclined slightly from a true horizontal bearing.
  • The raw materials start at the high end of the rotary kiln and as it reaches the lower end, a roaring blast of flame from burning powdered coal, oil, gas or other fuels takes place under precisely controlled conditions.
  • During the process of moving through the kiln, elements are off-gassed while the remaining elements combine to create a different substance, called clinker, which is discharged from the kiln as red-hot gray balls the size of marbles.
  • The clinker is then annealed through a slow cooling process in a range of chambers, with the heated air from those chambers being returned to the kiln to save fuel and improve efficiency.
  • Once cooled, the clinker is ground in the cement plant and mixed with small amounts of gypsum or limestone, after which it’s ready to be sold for use by homeowners, construction crews and ready-mix companies.
  • The materials that are added often impact the type of cement that is being created, with ingredients such as fly ash retarding set time and making it easier to work in the hot summer, while accelerants speed up the process when the weather is cold.

 

Now that you have a better understanding of what cement is made of, you can gain a better appreciation for the entire process and materials that go into it. If you’re considering a new cement or concrete project and need tools, BN Products are ready to help. Here’s what we have to offer.