Abstract
Effect of expanding aluminate hardening additives dispersity on formation of cement stone structure is studied. It is shown that the greatest expansion effect in combination with stone high strength is due to 4CaO3Al2O3CaOSiO2 mineral fractions of 45-63 μm in size. Large crystals of ettringite are gradually formed in hardening stone, when finely ground component of Portland cement becomes highly strong due to its rapid hydration. Under these circumstances, ettringite crystallization results in system expansion.
Highlights
Cement stone structure depends on many factors
Effect of expanding component dispersity on the formation of cement stone structure was studied on Portland cement (OPC) mixtures with an expanding component of calcium sulfoaluminate fractions of various sizes: < 28 μm, 28-45, 45-63, 63-80 and < 80 μm
Sample degree of hydration was estimated by the change in the intensity of main analytical peak of 4CaO3Al2O3CaOSiO2 mineral — (d = 0,372 nm), Portland cement clinker degree of hydration was estimated by alit
Summary
Cement stone structure depends on many factors. The main ones are the amount of hydrates and porosity [1-5]. The structure always varies depending on composition and amount of crystalline hydrates formed. Crystalline hydrates formation is determined by such factors as presence of impurities in minerals, hardening conditions, and hardening system dispersity. Various materials are used as expanding additives [6-12]. Aluminate hardening materials are widely used as expanding additives [13-18]. Calcium sulfoaluminate (SAC) is used as an expanding additive for this paper
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