When operating concrete and reinforced concrete structures in gas-air medium characterized by high concentration of carbon dioxide, increased relative humidity, ambient temperature variability, factors of periodic freezing and thawing, and others, a decrease of their strength is observed due to leakage of physical and chemical processes of migration of CO2 into the cement stone, and Ca (OH) 2 to its surface, what leads to:
- decomposition of ettringite that bears initial strength, conversion of the hydrosilicate phase into sulfocarbosilicate phase (thaumas), decrease of the main binder of hydrated cement and deformation of expansion of the cement stone,
- decrease of pH of the liquid phase at the surface of steel reinforcement that leads to the corrosion of this steel reinforcement.
JSC NIITSEMENT has developed blended cements with organic-mineral additives, chemical and mineralogical composition of which ensures the formation of heterocontact microstructure in the cement stone to increase the service life of concrete and reinforced concrete products in terms of carbonate aggression by 1,5 - 8,5 times.
One of the essential aspects of the production of blended cements, including blended cements applicable to medium with a high content of CO2, is maintenance of the optimum dosage of additives used, including organic additives, in their material composition, what can be carried out using developed by JSC NIICEMENT methods of determining the material composition of both the initial organic-mineral additive and its mass fraction in cement.
This offer is carried out upon customers’ request by the Chemical-Analytical (Testing) Lab. of JSC NIICEMENT.
Ul. Pleshcheevskaya, 15, Podolsk, 142101 Moscow region, Russia
Irina E. Kovaleva
Head of Chemical-Analytical Lab.