Effect of the starting fly ash on the microstructure and mechanical properties of fly ash-belite cement mortars

The effect of two kinds of Spanish fly ashes ASTM (class F) on the mechanical and microstructure parameters of fly ash-belite cement (FABC) mortars was studied for up to 200 days from mixing. Pore-size distribution analyses were carried out by mercury intrusion porosimetry, and microstructure was investigated by scanning electron microscopy (SEM). The pore solution was expressed and analyzed at different periods of hydration. The results showed that the alkali and iron content of the starting fly ash strongly influenced the kinetics of hydration of the FABC cements. If the time factor is deleted, general correlation is obtained between the mechanical and microstructure parameters studied, irrespective of both the starting fly ash characteristics and the calcination temperature. (C) 2000 Elsevier Science Ltd. All rights reserved.