Abstract: An improved process for producing portland and portland type cement clinker wherein argillaceous and calcareous type materials are ground and blended to form a generally homogeneous mixture and subsequently burned in a kiln at a temperature in the range of about 1200.degree. C. to about 1500.degree. C. to form cement clinker, the improvement comprising incorporating into the mixture a fluorine containing mineral acid, selected from the group comprising fluotitanic acid, fluoboric acid, fluophosphoric acid, fluosilicic acid, and hydrofluoric acid, as a fluxing and mineralizing agent, in an amount of up to 3.0% by weight based upon the weight of the dry solids in the mixture.

Abstract: An improved expansive cement composition is provided which has the increased capability of being able to " grab" steel reinforcement members therewithin as the material is curing and expanding to result in effective stressing of the reinforcement members. This cement is made of particulate argillaceous and calcareous materials, and contains from about 1 to about 70% by weight of free CaO and from about 2 to about 7% by weight of MgO uniformly distributed therein, with the remaining portion being primarily tricalcium silicate and containing substantially no dicalcium silicate.