The reaction of cement with water is exothermic. The reaction liberates a considerable quantity of heat This can be easily observed if a cement is gauged with water and placed in a thermos flask.
Test for heat o hydration is essentially required to be carried out for low heat cement only. This test is carried out over a few days by Vacuum Flask Methods, or over a longer period in an adiabatic calorimeter. When tested in a standard manner the heat of hydration of low heat Portland cement shall not be more than 65 cal gm. at 7 days and 75 cal/g. at 28 days.
