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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. Calcium silicate hydrate (also shown as C-S-H) is a result of the reaction between the silicate phases of Portland cement and water.
Tobermorite is a calcium silicate hydrate mineral with chemical formula: Ca 5 Si 6 O 16 (OH) 2 ·4H 2 O or Ca 5 Si 6 (O,OH) 18 ·5H 2 O. Two structural varieties are distinguished: tobermorite-11 Å and tobermorite-14 Å. Tobermorite occurs in hydrated cement paste and can be found in nature as an alteration mineral in metamorphosed limestone ...
The hydrate is referred to as the calcium silicate hydrate – "C-S-H-" – phase. It grows as a mass of interlocking needles that provide the strength of the hydrated cement system. High alite reactivity is desirable in Portland cement manufacture, and this is achieved by retaining, as far as possible, high temperature polymorphs, in crystals ...
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.
Jennite is often used in thermodynamical calculations to represent the pole of the less evolved calcium silicate hydrate (C-S-H). The value of its atomic Ca/Si or molecular CaO/SiO 2 (C/S) ratio is 1.50 (9/6), as directly calculated from its elementary composition formula. Tobermorite represents the more evolved pole with a C/S ratio of 0.83 (5/6).
Calcium silicate hydrate: C-A-H: Phase more complex than C-S-H: Calcium aluminate hydrate C-A-S-H: This is even more complex than C-S-H and C-A-H: Calcium aluminate silicate hydrate AFt: C 6 A S 3 H 32, sometimes with substitution of Fe for Al, and/or CO 2− 3 for SO 2− 4: Calcium trisulfoaluminate hydrate, or ettringite: AFm
The structure of the aluminosilicate framework is the same for scolecite, natrolite and mesolite. Scolecite has long ordered chains, rotated 24° round the axis of the chain. One Ca cation and three H 2 O molecules are in four ion sites in the channels parallel to the c crystal axis. There is no sign of aluminium ions occupying silicon ion sites.
Tacharanite is a calcium aluminium silicate hydrate (C-A-S-H) mineral of general chemical formula Ca 12 Al 2 Si 18 O 33 (OH) 36 with some resemblance to the calcium silicate hydrate (C-S-H) mineral tobermorite. It is often found in mineral assemblage with zeolites and other hydrated calcium silicates.