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Документ Development of decisions for alkali-activated cements proper deformations control(ПП «Технологічний Центр», 2019-11) Krivenko, P.; Gots, V.; Petropavlovskyi, O.; Rudenko, I.; Konstantynovskyi, O.; Kovalchuk, A.The relevance of using cements containing mineral admixtures of both natural and artificial origin is determined by compliance with current trends in sustainable mankind development in terms of efficient consumption of raw materials and energy and responsible attitude to the environment. From the environmental point of view, partial replacement of cement clinker with mineral admixtures contributes to the reduction of CO2 emissions. In addition, materials based on such cements are characterized by high quality, functionality and durability. For example, efficiency of using blast furnace slag, zeolite and limestone in composite eco-cements with high initial strength has been demonstrated [1].Документ Development of solutions concerning regulation of proper deformations in alkali-activated cements(ПП «Технологічний Центр», 2019-11) Krivenko, P.; Gots, V.; Petropavlovskyi, O.; Rudenko, I.; Konstantynovskyi, O.; Kovalchuk, A.The essence of the problem related to proper deformations in alkali-activated cements (AAC) complicated with high content of gel-like hydrate formations was analyzed. Cement types diametrically opposite in their compositions and, accordingly, in the content of gel phases during hydration, that is, the alkali-acti�- vated portland cement (AAPC) and alkali-activated slag cement (AASC) were taken for consideration. Approaches to formation of an effective structure of artificial stone counteracting shrinkage deformation by means of interference in structure formation when using complexes of mineral and organic compounds were proposed. Such compounds in composition of complex organomineral admixtures jointly influence intensification of crystallization processes and formation of an effective pore structure and morphology of hydrate phases while reducing water content in artificial stone. Salt electrolytes of various anionic types and anion-active surface-active substances were considered as ingredients of the proposed complex modifying admixtures. It has been found that the “salt electrolyte–surfactant” system is the most effective for AAPC modification. It was shown that modification of AAPC with this complex admixture based on NaNO3 reduced shrinkage from 0.406 to 0.017 mm/m. Instead, the use of Na2SO4 provided AAC of this type with a capacity of expansion up to 0.062 mm/m. It was shown that the effect of compensated shrinkage of modified AAPC is associated with a higher crystallization of low-basicity hydrosilicates (CSH(B)) and calcium hydroaluminates (CaO∙Al2O3∙10H2O). An additional effect is associated with formation of sulfate-containing sodium-calcium hydroaluminate (for the Na2SO4-based system) and crystalline calcium hydronitroaluminate (for the NaNO3-based system) with a corresponding microstructure stress. For further development, a complex admixture of “Portland cement clinker–salt electrolyte–surfactant” system was proposed for AASC modification. It provided shrinkage reduction from 0.984 mm/m to 0.683 mm/m. Minimization of the modified AASC shrinkage was explained by formation of sodium hydroalumosilicate of gmelinite type ((Na2Ca)∙Al2∙Si4∙O12∙6H2O) with a high degree of crystallization along with low-basicity calcium hydrosilicates. It was noted that the cement stone structure is characterized by high density, uniformity, and consolidation of hydrate formations.Документ Alkali activated portland cement with adjustable proper deformations for anchoring application(IOP Publishing Ltd, 2019) Krivenko, P. V.; Rudenko, I. I.; Petropavlovskyi, O. M.; Konstantynovskyi, O. P.; Kovalchuk, A. V.The application of alkali-activated Portland cement (hereinafter AAPC) for anchoring grouts was investigated with obtaining of non-shrinking high performance cementing systems. The AAPC system “ordinary Portland cement clinker – sodium metasilicate” was modified by the complexes of mineral and organic compounds to ensure specified properties of anchoring grouts. It was revealed that the most effective multifunctional additives are represented by the system “salt-electrolyte – surfactant”. Alongside with slowing down of AAPC paste setting time, the effect of compensated shrinkage of AAPC mortar, i.e. expansion within 0.062 mm/m and slight shrinkage within 0.017 mm/m, was ensured when Na2SO4 and NaNO3 were used in the mentioned system respectively. The effect of compensated shrinkage is explained by greater crystallization of ydrosilicates and hydroaluminates, additional formation of sulfate-containing sodium-calcium hydroaluminate (for Na2SO4-based system) and crystalline calcium hydronitroaluminate (for NaNO3-based system). The advantages of the modified AAPC for anchoring application are indicated in thepaper.Документ Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion(EDP Sciences, 2020-04) Krivenko, Pavlo; Petropavlovskyi, Oleh; Kovalchuk, Oleksandr; Rudenko, Igor; Konstantynovskyi, OleksandrThe paper is devoted to mitigation of steel reinforcement corrosion in alkali-activated slag cement (further, AASC) concretes, based on soluble sodium silicates (further, SSS’s), obtained from high consistensy concrete mixes. Enhancement of AASC fine concretes crack resistance due to modification by complex shrinkage-reducing additives (further, SRA’s) based on surfactants and trisodium phosphate Na3PO4.12H2O (further, TSP) was proposed for mitigation of steel reinforcement corrosion. SSS’s were presented by sodium metasilicate (silica modulus 1.0, dry state) and water glass (silica modulus 2.9, density 1400 kg/m3). In case of sodium metasilicate the application of SRA composition “ordinary portland cement clinker – TSP – sodium lignosulphonate – sodium gluconate” provides enhancement of crack resistance starting from early age structure formation with restriction of drying shrinkage from 0,984 to 0,713 mm/m after 80 d. The effect is caused by reduction of water and by higher volume of crystalline hydrates. In turn, SRA presented by compositions “TSP – glycerol” and “TSP – glycerol – polyacrylamide” provide enhancement of AASC fine concretes fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 – 49 % if compare with the reference AASC when water glass is used.