The influence οf cement paste alkalies upon mechanical quantities is considered to result from the changes in the liquid phase composition caused by sodium and potassium sulphates and from the changes in the hydraulic activity of clinker minerals due to the building - in of alkalies into the crystal lattice οί minerals. The influence of alkalies upon the solution composition through the changes of clinker phase and gypsum solubility shows impact upon the water demand and the Theological qualities of cement pastes . According to Odler and others (l) the Theological qualities of cement pastes depend primarily on w/c, hydration time, mixing intensity and £ine-graininess. The chemical and mineral composition is considered less important. The effects of Ge-bauer's and Schramla's (2) studies point to the significant influence of the following factors upon the water demand; C3A content, the total content of alkalies and the content of 10 - 30 µm grains, It has been proved that, of all parameters under investigation, the water demand of cements is linearly correlated with the water-demand of concretes made from these cements. Johansen's tests on cement pastes, as cited Jawed and Skal-ny ( 3 ), showed that the amount of water bound during the three minutes ' hydration is negatively correlated with the twenty - eight days' strenght. This suggests that reactions occurring during very early contact of cement and water have a sig-nificant influence upon the forthcoming development of strenght , The practical consequence of early cement hydration reactions can be found in the Theological qualities of the paste , The consistence of fresh cement pastes results from the overlapping of effects that flocculate and delay the early hydration of aluminates by means of gypsum. The impact of gypsum is modified by the presence of alkalies . According to Bombled (4), the sulphates of alkalies decrease the paste deform ability, shorten considerably the time of setting , Κ > Na, and weaken the strenght. Ish-Shalom and Greenberg (5) have proved that alkalies, while having little influence upon the plastic viscosity of cement pastes, increase greatly the yield value, in proportion to the content of alkalies . This paper presents the results of the research work into the influence of alkalies upon the Theological qualities of clinker and cement pastes during the first hour of hydration with regard to the kind and origin of alkalies .
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