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How do calcium silicates react with water during cement hydration?

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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.

When Portland cement is mixed with water, the primary hydraulic constituents—the calcium silicates ( $C_{3} S$ and $C_{2} S$ )—undergo chemical reactions involving both hydration and hydrolysis.12

These reactions produce calcium hydroxide ( $C H$ ) and calcium silicate hydrate ( $C - S - H$ ), an amorphous gel that acts as the binding material for concrete. The reactions can be represented as follows:1

$2 C_{3} S + 6 H \to C_{3} S_{2} H_{3} + 3 C H$
$2 C_{2} S + 4 H \to C_{3} S_{2} H_{3} + C H$

The process begins with the dissolution of the parent compounds, which releases significant heat. This is followed by a crucial dormant period that allows for the placement of the material before it begins to harden. As hydration continues, the $C - S - H$ and $C H$ products form, consuming water and cement while maintaining nearly the same total volume as the original mixture, which helps keep shrinkage manageable. While $C - S - H$ is often represented by the formula $C_{3} S_{2} H_{3}$ , it is not a uniform structure but rather a gel with a highly variable stoichiometry.1