Influence of the microsilica-superplasticizer complex on formation of structure and properties of cement stone

The features of hydration and hardening of cement systems of high performance concretes with the use of calorimetric measurement method have been studied and supplemented. Based on the results of the study, the influence of complex additives based on microsilica and superplasticizers on the processes of formation of the structure and properties of cement stone was determined. Electronic microscopy, X-ray phase analysis, derivatography, calorimetry and physical-mechanical methods for analyzing the properties of cement stone were used for the studies. It was established that superplasticizers, in addition to rheological and water-reducing properties, reveal the functions as regulators of setting and hardening of cement, and polycarboxylate superplasticizers contribute to the formation of a special, amorphized microstructure of cement stone. Thus, the polycarboxylate superplasticizer in combination with microsilica favors the formation of a cement stone structure consisting mainly of weakly crystallized low-basic calcium hydrosilicates. This structure is able to resist cyclic freezing and thawing, moistening and drying and even cyclic loading, which is very important for road concretes.