Київський національний університет будівництва і архітектури
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Mitigation of Corrosion Initiated by Cl− and SO42−ions in Blast Furnace Cement Concrete Mixed with Sea Water
(MDPI, 2022-01-01) Krivenko, Pavel; Rudenko, Igor; Konstantynovskyi, Oleksandr; Vaičiukynienė, Danutė
The use of blast furnace cement is an effective way to meet the requirements of sustainable development. However, CEM III/C is characterized by slow strength gain. The problem can be worse for plasticized reinforced blast furnace cement concretes mixed with sea water in view of shorter durability. The mitigation of corrosion in plasticized blast furnace cement concretes mixed with sea water can be provided through a composition of minor additional constituents, with percentage by mass of the main constituents: alkali metal compounds, 2…3; calcium aluminate cement, 1; clinoptilolite, 1. The alkali metal compounds are known to activate hydraulic properties of ground granulated blast furnace slag. A calcium aluminate cement promotes the accelerated chemical binding of Cl and SO-ions with the formation of Kuzel's salt. A clinoptilolite occludes these aggressive ions. The positive effects of the mentioned minor additional constituents in the blast furnace cement were supported by the increased early strength gain and the higher structural density, as well as by a good state of steel reinforcement, in the plasticized concretes mixed with sea water.
Prevention of steel reinforcement corrosion in alkali-activated slag cement concrete mixed with seawater
(EDP Sciences, 2021) Pavlo Krivenko; Igor Rudenko; Oleksandr Konstantynovskyi; Olha Boiko; S. Semerikov; S. Chukharev; S. Sakhno; A. Striuk; A. Iatsyshyn; S. Klimov; V. Osadchyi; T. Vakaliuk; P. Nechypurenko; O. Bondarenko; H. Danylchuk
Concretes mixed with seawater are characterised by enhanced performances, but action of chlorides and sulfates ensures the risk of reinforcement corrosion. Application of high consistency fresh concretes ensures changes in hardened concrete structure that causes the problem of steel reinforcement passive state ensuring. Thus mixing of plasticized concretes by seawater actualizes the search for means of steel corrosion prevention. Alkali-activated slag cements (further, AASC’s) reduce effect of ions Cl−and SO42−on steel reinforcement in concrete due to their exchange for ions OH−in the structure of zeolite-like alkaline hydroaluminosilicates. Complex additive «portland cement - calcium aluminate cement - clinoptilolite» was proposed to enhance the protective properties of AASC concretes to steel reinforcement. The results of DTA, X-ray diffraction, electron microscopy, microprobe analysis show that complex additive ensures to prevent steel reinforcement corrosion in AASC concrete mixed with seawater due to binding Cl−and SO42−ions in Kuzel’s salt in AASC hydration products and exchange of these aggressive ions with OH−ions in the structure of clinoptilolite. This effect of complex additive confirmed by surface state and the absence of mass loss of steel rebars embedded in plasticized AASC fine concrete mixed with seawater after 90 d of hardening.
Етнографія України: методичні рекомендації для студентів, які навчаються за спеціальністю 242 «Туризм».
(КНУБА, ФО-П Шпак В. Б., 2022) Дьомкін, Петро Олексійович; Ноняк, Михайло Васильович
Містять зміст лекційної частини курсу, плани семінарських занять, тематику індивідуальних завдань, питання до підсумкового контролю, список рекомендованої літератури.
Призначено для студентів, які навчаються за спеціальністю 242 «Туризм».