Hydration and strength gain of sulfoferrite clinkers and special cements based on those

The potential of sulfoferrite clinkers synthesized from iron-containing industrial wastes as an expanding additive in sulfoferrite cements was investigated. The data on heat release during hydration of expanding additives, as well as the results of a comprehensive thermal analysis of the hydration products indicate that sulfoferrite clinkers have binding properties. Due to the difference in the mineralogical composition of sulfoferrite clinkers, in their hydration various hydrates are formed (ferruginous ettringite, calcium sulfate dihydrate, Portlandite, calcium hydrosilicates, etc.), which directly affect the microstructure and density of the cement stone. The results showed that shrinkproof compositions can be obtained only with strict control of the content of expanding additives in mixed sulfoferrite cements, which, depending on their mineralogical and fractional make-up, should be in the range of 4-6%. Exceeding this limit leads to excessive stresses in the structure of cement stone and its further deterioration. By changing the fineness of grinding the expanding additive, its hydration can be intensified allowing to adjust the properties of mixed cements, such as density, expansion, strength, etc.

Author: I.N. Borisov, A.A. Grebenyuk

Section: Science and production

Keywords: sulfoferrite clinker, ferric ettringite, portlandite, expanding additive, linear expansion, composite sulfoferrite cement