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How does cement act as a binding material in concrete?

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Cement The cement-making process, from crushing and grinding of raw materials, through roasting of the ground and mixed ingredients, to final cooling and storing of the finished product.

Cement acts as a binding material in concrete through a chemical process known as hydration. When portland cement—a finely ground powder—is mixed with water, its primary constituents, specifically calcium silicates, react with the water molecules.123

This reaction produces calcium silicate hydrate (C–S–H) and calcium hydroxide. C–S–H forms an amorphous, gel-like material that serves as the essential cementitious binder. As this hydration proceeds, the mixture hardens, effectively bonding aggregate particles together into a solid, durable mass.324

The process includes a critical "dormant period" after initial mixing, which allows the material to remain workable before it begins to set and gain strength. Because these chemical reactions occur even in the presence of water, these materials are classified as hydraulic cements. The resulting paste fills the spaces between aggregate particles, ensuring the concrete achieves its structural integrity.324