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When water is added to cement, each of the compounds undergoes hydration and contributes to the final state of the concrete. [2] Only calcium silicates contribute to the strength. Tricalcium silicate is responsible for most of the early strength (first 7 days). [3] Dicalcium silicate, which reacts more slowly, only contributes to late strength.
Dicalcium silicate is stable, and is readily prepared from reactive CaO and SiO 2 at 300 °C. The low temperature form is γ-belite, or lime olivine. This form does not hydrate, and is avoided in cement manufacture. As the temperature rises, it passes through several polymorphic states:
Calcium-silicate passive fire protection board being clad around steel structure in order to achieve a fire-resistance rating. Calcium silicate is commonly used as a safe alternative to asbestos for high-temperature insulation materials. Industrial-grade piping and equipment insulation is often fabricated from calcium silicate.
Cement hydration and strength development mainly depend on two silicate phases: tricalcium silicate (C 3 S) , and dicalcium silicate (C 2 S) . [1] Upon hydration, the main reaction products are calcium silicate hydrates (C-S-H) and calcium hydroxide Ca(OH) 2, written as CH in the cement chemist notation. C-S-H is the phase playing the role of ...
The ratio Ca/Si (C/S) and Mg/Si (M/S) decrease from 2 for the dicalcium and dimagnesium silicate reagents to 1.5 for the hydrated silicate products of the hydration reaction. In other term, the C-S-H or the serpentine are less rich in Ca and Mg respectively.
The hydration reactions of calcium aluminate cements are very complex. The strength-developing phases are monocalcium aluminate ( CA ), dodeca-calcium hepta-aluminate ( C 12 A 7 ), and belite ( C 2 S ), a dicalcium silicate.
The grinding process is controlled to obtain a powder with a broad particle size range, in which typically 15% by mass consists of particles below 5 μm diameter, and 5% of particles above 45 μm. The measure of fineness usually used is the ' specific surface area ', which is the total particle surface area of a unit mass of cement.
The chemical process for hydraulic cement ... The lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate. ... The hydration products ...