shows the heat evolution curve obtained by isothermal conduction calorimetry of the samples at 27 C for 24 h. It is important to mention here that mixing was carried out outside the instrument and the mixed pastes then introduced into the calorimeter. Time zero on the plots represents the time at which the sample was placed in the instrument, which was 2 min after the start of mixing in each case. The straight line in the beginning can be assigned to pre-induction stage which converged into peak without any induction period. This peak can be assigned to dissolution of alumino-silicate present in fly ash and precipitation of CSH (C = CaO, S=SiO2,H=H2O) gel [36].