Building Materials
The compound of Portland cement which contributes to the strength after two to three years is

Tri-calcium silicate
Di-calcium silicate
Tri-calcium aluminate
Tetra-calcium alumino ferrite

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Building Materials
Asbestos

All of these
Contains iron oxide and alumina
Is composed of hydrous silicates of calcium and magnesium (CaSiO3, 3MgSiO3)
Is a natural fibrous mineral substance

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