Consider the following statements:
1. The rate of setting time of cement paste is controlled by regulating the ratio SiO2/(Al2O3 + Fe2O3)
2. The alkalies accelerates the setting of cement paste.
3. The calcium hydroxide crystals also known as portlandite consist of 20 – 25% volume of the solid in the hydrated paste.
Which of the above statements is(are) CORRECT?
1
1 only
2
1 and 2
3
2 and 3
4
1, 2 and 3