Bleeding and rheological properties of alkali activated fly ash-slag at different temperatures

Abstract

 The bleeding and rheological properties of three sets of alkali-activated fly ash-slag pastes at different temperatures were investigated. The results indicate that the ratio of slag-to-fly ash and temperature have a significant impact on the bleeding rate and rheological properties of the paste. The bleeding rate of alkali-activated fly ash-slag system gradually decreases with the increase of temperature. And as the content of fly ash gradually increases, the bleeding rate further increases. In addition, the thixotropic area of the paste exhibits a change similar to the yield stress, that is, when the temperature and fly ash content increase, both rheological parameters significantly increase. In the early stage of hydration, the degree of hydration of all samples is not high, manifested as no significant dissolution of fly ash and slag particles observed. At the same degree of bleeding, the paste with higher temperature exhibit relatively higher yield stress and lower thixotropy, indicating that the accelerated hydration rate of pastes in high-temperature environments leads to more stable microstructures.