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The alite found in Portland cement differs in composition from simple tricalcium silicate. It is a solid solution and contains minor amounts of other oxides besides CaO and SiO 2. A typical composition is: [4]
MTA is composed mostly of tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite, with calcium sulfate and bismuth oxide as minor constituents. [3] The later 4 phases vary among the commercial products available.
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 ...
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.
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.
Tricalcium silicate (C 3 S, alite, Ca 3 SiO 5) is thermodynamically unstable below 1250 °C, but can be preserved in a metastable state at room temperature by fast cooling : on slow cooling it tends to revert to belite (Ca 2 SiO 4) and CaO. If the reaction is incomplete, excessive amounts of free calcium oxide remain in the clinker. Regular ...
C 3 A: tricalcium aluminate (3CaO·Al 2 O 3) (historically, and still occasionally, called celite); C 4 AF: brownmillerite (4CaO·Al 2 O 3 ·Fe 2 O 3 ). The silicates are responsible for the cement's mechanical properties — the tricalcium aluminate and brownmillerite are essential for the formation of the liquid phase during the sintering ...
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.