Intermediate Topic 631 of 1102 Inorganic Chemistry
Cement
A mixture of calcium silicates and aluminates that hardens through hydration.
In-depth explanation of Cement
Portland cement is made by heating limestone and clay in a rotary kiln to about 1450 degrees C, which produces clinker, a mixture of calcium silicates such as Ca3SiO5 and Ca2SiO4 with calcium aluminates. The clinker is ground with about 5 percent gypsum, which controls the setting rate. When water is added, the calcium silicates hydrate to a gel of calcium silicate hydrate that binds the particles together. Hydration is exothermic and continues for days or weeks, so concrete keeps gaining strength. Cement production accounts for roughly 8 percent of global carbon dioxide emissions.
Going deeper: Cement
Key ideas: Portland cement is made from limestone and clay heated in a rotary kiln near 1450 C to form clinker, then ground with 2 to 5 percent gypsum to slow setting. Major phases: tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and ferrite phase. Setting is hydration forming calcium silicate hydrate gel; concrete is cement + sand + aggregate + water.
Common mistakes and connections: Students say cement dries as it hardens; it cures chemically and even underwater. Skipping gypsum gives flash set from C3A. Kiln making is among the largest CO2 emitters, about 0.8 tonne per tonne of cement, from calcination plus fuel. Links to calcium compounds, silicates and exothermic hydration.
Visualization of Cement
Typical Portland cement composition: calcium silicates dominate and hydrate to the calcium silicate hydrate gel that gives concrete strength. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Concrete is made by mixing cement, sand, gravel and water in proportions chosen for the required strength.
Frequently asked questions about Cement
What is Cement?
A mixture of calcium silicates and aluminates that hardens through hydration.
Is Cement a beginner, intermediate or advanced topic?
Cement is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Cement?
Study these earlier topics in Inorganic Chemistry first: Alkaline Earth Metals, Calcium Compounds, Plaster of Paris.
What comes after Cement?
The next topics in Inorganic Chemistry are Magnesium Chemistry and Boron Family.
Can I practise Cement with quizzes?
Yes. The interactive lesson includes a self-check question on Cement, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Cement fits in Inorganic Chemistry
Cement is topic 16 of 113 in Inorganic Chemistry.