The effect of added finely dispersed calcite on the corrosion resistance of cement compositions

Abstract

Many types of the corrosion of Portland cement stone immersed into inorganic liquid media are conditioned by chemical exchange reactions between the substances dissolved in them and cement hydration products. To prevent the corrosion formation in corrosive media it is necessary to form cement clinker hydration products that do not enter into ion exchange reactions in the solutions. The concrete structure defines the penetration rate of corrosive ions and that of the removal of corrosion products, in other words the behavior of corrosive processes. The investigations that were carried out showed that the presence of finely dispersed organogenic calcite (chalk) in the cement stone composition results in a change of the phase composition of the hydrates of new formations, i.e. it results in a decreased content of the free calcium hydroxide and the binding of aluminate phases to form stable hydration products. The use of this additive contributes also to the compaction of the microstructure of cement stone due to the occupation by additive grains of the vacancies in the gaps between the cement grains and due to an increased dispersion of hydration products for which calcite particles serve as crystallization centers. All these factors contribute to an increased corrosion resistance of the cement stone and the concrete exposed to the action of corrosive solutions.