Развитие шельфовых месторождений углеводородного сырья в России способствует внедрению новых типов морских стационарных платформ гравитационного типа. Строительство этих объектов должно быть технико-экономически обоснованным, с обеспечением требуемой надежности и долговечности. Одним из критериев обоснования является гарантированный прогноз жизненного цикла платформ, который может вызвать преждевременную остановку деятельности платформы для проведения ремонтно-восстановительных работ. Поэтому поиск оптимальных методов оценки жизненного цикла является актуальной задачей. Проведенная оценка воздействия эксплуатационных сред на железобетонные платформы показала, что набольшее воздействие оказывают ионы хлоридов и углекислый газ в зоне переменного увлажнения стволовой части кессона. В статье приводится анализ зарубежных нормативно-технических документов в области обеспечения долговечности бетона и железобетона в сравнении с отечественным стандартом. Последний показал существенные отставания требований к мерам первичной защиты, а именно в обеспечении плотности бетона, расхода цемента и др. Приводятся результаты анализа жизненного цикла железобетона при воздействии углекислого газа с учетом по модели «Duracrete» для надводной части платформ «Беркут», «Пельтун-Астохская-Б» и «Лунская-А». Определены параметры жизненного цикла платформы-индекс надежности и вероятность риска, которые показали, что при толщине защитного слоя 50 мм полная потеря надежности произойдет через 100 лет, пересечение кривых индекса надежности
The development of low-carbon alkali-activated binders based on production waste is one of the most sought-after areas of development of building materials science. The article examines the results of studies of the structures of cupola dust and the assessment of its ability to hydrate when exposed to alkaline activation. Technological preparation of dust by sifting it through a 0.16 mm sieve and subsequent mechanical activation for 120 s to a specific surface area of 733 m2/kg is proposed. The best results were shown by the composition of cupola dust with an alkaline activator of 50 wt.% 8.3 M NaOH and 50 wt.% Na2SiO3. After 28 days of natural hardening for this composition, the bending strength was 12.7 MPa and the compressive strength was 68.3 MPa. The analysis of the influence of hardening conditions showed that the temperature–humidity treatment of concrete at a temperature of 90 °C for 12 h accelerates the process of curing to 80–90% of natural conditions. The porosity of the samples after heating was established, which is 24–25%. The mineralogical composition of the products of the cement matrix structure’s formation, which is represented by minerals of the zeolite group, was specified.
Provision of reliability of structures is an important issue at the designing stage. One of reliability aspects is durability. In order to estimate the durability of reinforced concrete it is required to apply standard procedure of calculation which, according to SNIP Regulations 2.03.11-85 Protection of Engineering Structures against Corrosion, can be implemented with the use of means of primary and secondary protection 1 . A peculiar feature of buildings with built-up or monolithic framework is that the major portion of reinforced concrete items remains in the structure of multi-layer walls and cannot be reached for renewal of the means of secondary protection. That is, in order to provide durability of structures it is possible to rely only on the means of primary protection. The article discusses estimations of parameters of concrete protective layer (its thickness and density), based in numerical solution of differential equations, which describe carbonization and guarantee protection of reinforcement against corrosion for the design operation lifetime of structure.
The aggressive environment of oil refineries contributes to increased corrosion of reinforced concrete supports of trunk pipelines. This is primarily due to the increased concentration of acid gases. The article presents results of the analysis of the gas-air environment of an oil refinery and its impact on primary support measures. It was established that when using typical reinforced concrete supports made from B15 W2 concrete, the protective layer with a thickness of 15 mm becomes neutralized 3-6 years after the operation. To ensure continuous 25-year operation, it is necessary to increase thickness of the protective layer to 35 mm. To increase the durability of the structure, it is proposed to replace steel reinforcement with “metal-fiberglass” or hybrid fiberglass one.
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