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Документ Effect of sodium phosphate and sodium nitrate on microstructure of alkali-activated slag cement pastes and properties of reinforced concrete under cyclic drying-wetting in sea water(AIP Publishing, 2023) Krivenko P.; Rudenko I.; Konstantynovskyi O.; Boiko O.; Vaičiukynienė D.The relevance of alkali activated slag cement (AASC) concretes for marine structures is due to their enhanced resistance to sea water. However, cyclic influence of sea water and drying under the action of atmospheric carbonic gas in actual operating conditions cause risks of both deterioration of concrete and corrosion of steel reinforcement. These risks increase in case of fresh concretes with high consistency. Application of salts of strong acids, i.e. sodium phosphate and sodium nitrate, in combination with complex multifunctional additive «portland cement - alumina cement - clinoptilolite» was proposed to protect plasticized AASC concrete from the influence of cyclic drying-wetting in sea water with combination of exposure classes XC4 and XS3. It was shown the advanced crystallization of AASC microstructure due to the mentioned salts as admixtures. Corrosion resistance potential of AASC concrete can be improved due to application of specified salts in combination with the mentioned complex additive as factor of aggressive ions (Cl-, SO42- and CO32-) binding. The modified in proposed way plasticized AASC concrete was characterized by the advanced performances, i.e. pore structure, structural density, strength, corrosion resistance, state of steel reinforcement after 90 cycles of wetting/drying in sea water.Документ Comparison of influence of surfactants on thermokinetic characteristics of alkali-activated slag cement(Private Company Technology Center, 2021-11-26) Krivenko Pavlo; Rudenko Igor; Konstantynovskyi OleksandrIncreasing the durability of concrete and reinforced concrete structures according to the criterion of crack resistance is a relevant task of construction materials science. To solve this task, this paper proposes effective solutions for adjusting thermofinite characteristics of alkali-activated slag cement (ASC) by using surfactants of various chemical nature in order to control the thermally-stressed state of concrete based on it (ASC concrete). The method of calorimetry was applied to show that the problematic issue is to adjust the structure formation of ASC by anion-active surface-active substances based on complex polyesters. This is predetermined by the instability of the molecular structure of surfactants in the hydration environment of ASC due to the destruction of complex ester bonds as a result of alkaline hydrolysis. Thermokinetic analysis has demonstrated the effectiveness of using anion-active surfactants, which do not contain ester bonds, as regulators of crack resistance of ASC concrete. Simple polyesters and multi-atom alcohols provide the ability to adjust the duration of the induction period while ensuring the required completeness of ASC hydration within a time frame. The effectiveness of cation-active surface-active substances has been shown, which are characterized by the stability of the molecular structure in the hydration environment of ASC and an increased level of adsorbing capacity. The decrease in the effectiveness of surface-active substances has been shown, in terms of the effect on the heat release of ASC, in the following series: alkaline salt of carboxylic acid>salt of the quaternary ammonium compound>simple polyester> polyalcohol>complex polyester. The reported results are important in view of the possibility of effective adjustment of ASC heat release by influencing the structure formation of surfactant with a certain molecular arrangement in order to predictably reduce crack formation in a thermally-stressed state and a corresponding increase in the durability of structures.Документ Вплив органо-мінеральних комплексів на міцність і власні деформації шлаколужних цементів(ОДАБА, 2019) Кривенко, П. В.; Петропавловський, О. М.; Руденко, І. І.; Константиновський, О. П.Запропоновано комплексну органо-мінеральну добавку складу «портландцементний клінкер – електроліт – поверхнево-активна речовина», використання якої в шлаколужному цементі забезпечує сповільнення строків тужавлення, підвищення показників міцності і практично відсутність усадки (0,062 мм/м). Показано особливості роботи портландцементного клінкеру у лужному середовищі, вплив добавок солей різного аніонного типу та луговміщуючих аніоноактивних ПАР на водопотребу, синтез міцності та власні деформації при гідратації та формування структури штучного каменя на його основі. Відмічена перспективність запровадження таких органо-мінеральних комплексів в якості додаткових компонентів шлаколужних цементів для регулювання їх технологічними і фізико-механічними властивостями, у т.ч. для зменшення усадки цементного каменяДокумент 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.Документ 35. The influence of complex additive on strength and proper deformations of alkali-activated slag cements(Trans Tech Publications Ltd, 2019) Krivenko, Pavel; Petropavlovskyi, Oleh; Rudenko, Igor; Konstantynovskyi, OleksandrThe peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker -mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na2SO4 and NaNO3. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na2SO4. Almost no shrinkage is supplied by application of NaNO3 (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO3 - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.Документ Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion(EDP Sciences, 2020-04-22) Petropavlovskyi, Oleh; Kovalchuk, Oleksandr; Krivenko, Pavlo; 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 Na3PO .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.