Concrete and cement: I) Give an example of non-calcium silicate cement II) Can Portland cement hydrate without exposure to air? Solution (i)Answer:- Example for non calcium silicate cement is High alumina cement or cement fondu. The principal compound of cement fondu is mono calcium aluminate. (ii)Answer:- Yes cement can hydrate without exposure to air. 2Ca3SiO5 + 7 H2O = 3 CaO.2SiO2.4H2O + 3 Ca(OH)2.