How is cement made?
Cement is one of the core ingredients in concrete. The cement powder forms a paste when mixed with water that binds to sand and crushed stone to form strong concrete. Cement is made from limestone and a few other minerals that are chemically-treated and roasted in a furnace.
The limestone is mixed with other minerals, such as clay, fly ash, silica sand and iron ore. They are heated to form a hard rock-like substance, which is then ground into a fine grey powder – cement as we know it.
Steps to making cement powder
Step 1: Core ingredients are delivered to the cement factory. The limestone is crushed by a series of rolling crushers and hammers and is then sent via conveyor to the next stage.
Step 2: The crushed limestone is mixed with sand and clay in large vats. The resulting mixture is then fed into a kiln.
Step 3: The cement kiln heats the mixture to 1500℃ in large cylindrical rotary drums lined with firebrick. These huge kilns are angled downwards so the ingredients move from one side to the other while being roasted. Gases are released from the mixture, leaving behind a new substance called clinker – small grey balls about the same size as marbles.
Step 4: The red-hot clinker is discharged from the lower end of the kiln and then fed into a clinker cooler. The heated air from the cooler is returned to the kiln, saving fuel and energy in the process.
Step 5: The cooled clinker is mixed with gypsum and then sent to a grinding mill where it is ground into a fine powder. Cement is so fine that one kilogram of powder contains about 300 billion grains.
Step 6: The cement powder is then sent to storage tanks where it is packaged into 50kg bags or delivered to building contractors in bulk tankers.
LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in the Mbeya Region at Songwe in Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.