Gypsum-less cement

In gypsum-less cement, a conduction calorimetric study showed that a strong retardation of hydration occurred in the presence of a lignosulfonate-based superplasticizer containing sodium carbonate. l... 

Parallel with cement production development the significant progress in cement chemistry was achieved. The real revolution we owe to French scientist Le Chat-eher. This great chemist determined the phase composition of Portland cement clinker and the hypothesis of hydration process. Le Chatelier stated that, similarly as in the case of gypsum, the anhydrite cement components dissolve, the solution became oversaturated in relation to hydrates, which causes their crystallization [3],... 

These discussions and doubts result first of all from the complexity of reaction of unhydrous cement phases with water. This can be illustrated taking into account a simple, on a first appearance, example of gypsum hemihydrate hydration. This reaction served as a basis of Le Chatelier s crystallization theory. The uncompUcated, at first sight, reaction ... 

In Table 7, the reference expansion values for the three red gypsum cements, as well as for the commercial cement, are shown. The results show that the presence of red gypsum in the cements formed does not cause any significant modification in its expansion behavior in comparison to the commercial cement, irrespective of the proportion of red gypsum used as an additive. And more important, the values comply with Spanish legislation, which indicates that the reference value for expansion obtained through the le Chatelier test for any cement should be lower than 10 mm... 

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