INFLUENCE OF FLY ASH ON EARLY HYDRATION AND PORE STRUCTURE OF CEMENT PASTES

The influence of fly ash with different additions on the early hydration and the pore structure of cement pastes were investigated by means of the mechanical tests, scatting electron microscopy, alternating current impedance and Mercury Intrusion Porosime-try (MIP). The results show that an increase of the fly ash addition in the cement causes a longer setting time of the cement, a decrease of the compressive strength, and an increase of the hydration velocity of clinker mineral. In addition, hydration velocity of the whole cement - fly ash system decreases. The electric resistance and the impedance in the pore solution decrease. The number of macro-pores becomes fewer in the cement pastes, but the number of micro-pores becomes more.