The effect of zeolite on the properties and hydration of blended cements

In this paper the properties and the hydration of cements containing natural zeolite, coming from the Metaxades area, Thrace, Greece, are studied. The experimental part comprises three stages. In the first stage a complete mineralogical characterization of the zeolite was performed. In addition, the pozzolanic reactivity of the zeolite was evaluated on the basis of the Chapelle test. In the second stage, the mechanical and physical properties of blended cements, incorporating 0%, 10% and 20% per weight of fine zeolite were determined. Finally, the hydration rate and products were studied by means of X-ray diffraction and FTIR spectroscopy, in combination with thermoanalytical methods (TG/DTG and DTA). As it is concluded, the examined zeolite consists mainly of heulandite type-II and is a pozzolanic material that contributes to the strength development of zeolite-cement mixtures, the consumption of Ca(OH)2 formed during the hydration of Portland cement and the formation of cement-like hydrated products. Finally, the addition of zeolite up to 20% w/w does not significantly affect the physical and mechanical properties of the blended cements.