The World's Building Block

Concrete is a mixture of cement, water, sand, and gravel (aggregate). The cement — usually Portland cement — is the chemically active ingredient that binds everything together through hydration reactions. It is the most consumed manufactured material on Earth.

Humanity uses roughly 30 billion tons of concrete per year — more than all other building materials combined. The Romans used a form of concrete to build the Pantheon, whose unreinforced dome has stood for nearly 2,000 years.