ПОЛУЧЕНИЕ СМЕШАННЫХ КОМПОЗИЦИОННЫХ ЦЕМЕНТОВ НА ОСНОВЕ ФЕРРИТНОГО КЛИНКЕРА

Abstract

The possibility of using ferritic clinker as a component of binders with special performance properties is considered. Such types of cements can solve the problems of providing the construction industry with high-strength, resistant to external aggressive effects and relatively cheap binders. However, the mechanism of hardening and curing of cement stone obtained by using ferritic clinkers is complicated and depends on a number of parameters.
 It was found that the greatest thermal effect (more than 70%) during the hydration of the resulting ferritic clinker with the introduction of various additives (lime and gypsum stone) is achieved up to 4 hours from the moment the binder compositions are mixed by means of a calorimetric analysis carried out during the hydration of the developed special binder compositions. That corresponds to the course of the induction period of hydration of the used Portland cement, at the time of the occurrence of primary contacts between crystalline hydrates and sufficient mobility of the cement mass. In this time interval, the strength of the cement stone is not high enough and the produced iron-containing hydration products are able to fill the space of the cement matrix, making it more dense and less defective. 
 The formation of iron-containing crystalline hydrates from ferritic clinker can proceed in several stages: hydrolysis of dicalcium ferrite at the initial stage of the reaction and further interaction of its products with portlandite in the period from 7 to 14 days from the moment of mixing the binder compositions. The main crystalline hydrates formed from ferritic clinker are iron-bearing ettringite and hydrogarnet.
 The study of the physical and mechanical characteristics of cement stone showed that the optimal content of ferritic clinker in the composition of the binder compositions is 5%. With a given quantity, the strength of the cement stone in compression and bending exceeds that of the control sample by 11.5%. The input of 15 and 30% ferritic clinkers into the composition of special binders reduces the strength characteristics by 15-20%.