Which one of the following statements is not correct regarding the setting of cement?

The setting of cement involves complex chemical reactions. Gypsum (CaSO₄) is added to Portland cement to regulate early-age properties by retarding the hydration of tricalcium aluminate (C₃A), thereby lengthening the setting period. Tricalcium silicate (C₃S) is the primary activator responsible for the initial setting and early strength development. Dicalcium silicate (C₂S) hydrates much more slowly and, along with C₃S, contributes to the final ultimate strength over a period of months to a year. Statement 2 is incorrect because, according to the colloidal theory, the formation of hydrated silicate gels (C-S-H) is the primary mechanism for the hardening and strength gain of cement. These gels do not cause the cement to lose strength; rather, they form the rigid binding network that provides structural integrity.

Sources

1. [1] https://eprints.whiterose.ac.uk/id/eprint/125760/1/Effect%20of%20sulfate%20on%20slag%20reaction%20%5BAccepted%20Manuscript%5D.pdf
2. [2] https://www.sciencedirect.com/topics/engineering/calcium-silicate-hydrate