The setting and hardening of cement are complex processes involving the hydration of its components. The colloidal theory describes the formation of hydration products as gels that eventually solidify. Gypsum (CaSO₄·2H₂O) is added to cement clinker to retard the setting time, preventing flash setting and allowing sufficient time for mixing, placing, and finishing. Tricalcium silicate (C₃S) hydrates relatively quickly and is primarily responsible for the initial set and early strength. Dicalcium silicate (C₂S) hydrates slowly and contributes significantly to the long-term strength gain of concrete.
Which one of the following statements is not correct regarding the setting of cement?
Asked in UPSC CAPF 2023 · Topic: Inorganic Chemistry (Solid State Inorganic Chemistry)
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Answer: B. According to the colloidal theory, gels of hydrated silicates are formed and when these gels harden, the set cement loses strength.
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