"Вестник МГСУ"

This article contains the results of studies of the use of additives containing crystallization components significantly affecting the curing of cement, improving the structure of cement stone and concrete. The crystalline component is obtained using the rotary-pulse unit, which provides not only the grinding of agents, but their interaction with each other as well in order to accelerate the hydration and structure formation in cement stone. The degree, and kinetics of hydration, the composition of hydrated phases, the structure of the additives and cement stone was studied using the following methods: x-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM). Mechanical properties of cement were determined by standard methods and techniques. The expander produced by means of hydrodynamic activation of the sulfoaluminate clinker (SAC) consists of ettringite and hydrated calcium silicates, which are characterized by high dispersion rate (less than 10 µm) and reactivity as the seed for the crystallization of hydrated compounds. The introduction of the ultrafine additives of the crystalline SAC (within 1-5%) was discovered to cause expansion of the cement stone. Implementation of the additives increases cement hydration and contributes to the formation of active centers of crystallization that lead to the fast formation of ettringite, hydrated calcium aluminates and calcium silicates. The activated crystalline additive provides for significant reduction of porosity, initial curing, and high strength of cement stone. In addition, the additive is an expansive component, forming needle-like crystals of ettringite during hydration. These microcrystals grow in the capillaries of cement stone, filling them, and create conditions for improving the crack resistance of cement concrete.