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cement, aggregate, water
Concrete is made of cement, aggregate (sand and gravel), and water. Cement is the binder, made from limestone heated with silica-rich materials like clay or volcanic ash. The water causes a chemical reaction called hydration, which hardens the mixture into a strong, durable material.
- 🪨 Limestone is the primary ingredient for cement, formed from ancient sea life.
- 🌋 Roman concrete was durable underwater due to volcanic ash (pozzolana), which allowed it to harden without drying.
- 🧪 Modern concrete uses Portland cement, a marketing term for cement made from limestone and shale/clay heated to form 'clinker'.
- ⚖️ Concrete is about three times denser than water, making it buoyant and difficult to sink in.
- 💧 Water is crucial for concrete's hardening process (hydration), becoming part of the solid material, not just evaporating.
A man wearing goggles is partially submerged in a large, clear bubble filled with concrete.