Analysis of the selection of building materials for the reconstruction of concrete and reinforced concrete structures damaged by an aggressive environment

2021 ◽  
Vol 80 (2) ◽  
pp. 188-194
Author(s):  
B.M. Aubakirova ◽  
◽  
Е.R. Onlasynov ◽  
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Aggressive Environment ◽  
Selection Of

This article discusses the results of the analysis of the use of building materials in the restoration of concrete and reinforced concrete structures of buildings and structures that erupt from an aggressive environment.

Damage of Reinforced Concrete Structures due to Steel Corrosion

2015 ◽  
Vol 1111 ◽  
pp. 187-192
Author(s):  
Corina Sosdean ◽  
Liviu Marsavina ◽  
Geert de Schutter
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Structural Integrity ◽  
Colorimetric Method ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Degradation Process ◽  
Reinforced Concrete Structures ◽  
Chloride Ingress ◽  
Rc Structures

Reinforced concrete (RC) became one of the most widely used modern building materials. In the last decades a great interest has been shown in studying reinforcement corrosion as it became one of the main factors of degradation and loss of structural integrity of RC structures. The degradation process is accelerated in the case of RC structures situated in aggressive environments like marine environments or subjected to de-icing salts. In this paper it is shown how steel corrosion of the embedded rebars occurs and how this affects the service life of reinforced concrete structures. Also, an experimental study regarding the combined effect of carbonation and chloride ingress was realized. Samples with and without rebars were drilled from a RC slab which was stored in the laboratory for two years. Non-steady state migration tests were realized in order to determine the chloride profile, while the carbonation depth was measured using the colorimetric method based on phenolphthalein spraying. It was concluded that carbonation has a significant effect on chloride ingress, increasing it.

scholarly journals Adhesion characteristics of geopolymer mortar to concrete and rebars

2019 ◽  
Vol 258 ◽  
pp. 01012 ◽  
Author(s):  
Sanjay Pareek ◽  
Hiroo Kashima ◽  
Ippei Maruyama ◽  
Yoshikazu Araki
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Concrete Structures ◽  
Acid Resistance ◽  
Steel Plates ◽  
Alkali Concentration ◽  
Reinforced Concrete Structures ◽  
Interfacial Zone ◽  
Adhesion Properties ◽  
Repair Materials

In recent years, geopolymers have gained a wide attention as highly ecological-friendly building materials, having a capability to cut down 70% of CO2 emissions in comparison to the ordinary cement concrete. In this study, geopolymer mortars are proposed as repair materials for reinforced concrete structures, due to their superior acid resistance, heat resistance and high strength in comparison to the existing repair materials. The objective of this study is to investigate the adhesion properties of geopolymer mortars to concrete substrates with different surface treatments, steel plates and rebars. As a result, the geopolymer mortars are found to have excellent adhesion properties to dry concrete substrates, steel plates and rebars. Concrete substrates treated with grinder, further enhanced the adhesion properties of geopolymer mortars. On the other hand, poor adhesion of geopolymer mortars to wet concrete substrates was observed due to the presence of water on the interfacial zone, which decreased the alkali concentration of the geopolymer, resulting in lower adhesion strength. In general, geopolymer mortars are found to have suitable adhesion properties to the concrete substrates, steel plates and rebars and can be applied as repair materials for reinforced concrete structures.

Prediction of durability of structural concrete in aggressive exposures

2018 ◽  
Author(s):  
Сергей Леонович ◽  
Sergey Leonovich ◽  
Валентин Доркин ◽  
Valentin Dorkin ◽  
Оксана Чернякевич ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Building Materials ◽  
Limit State ◽  
Concrete Structures ◽  
Life Cycles ◽  
Reinforced Concrete Structures ◽  
Concrete Durability ◽  
Concrete Carbonation ◽  
Corrosion Of Steel

The monograph is devoted to the prediction of the longevity of reinforced concrete structures, the destruction of which is associated with corrosion of steel reinforcement caused by chloride aggression or concrete carbonation. On the basis of a comprehensive analysis of models for calculating the service life of structures and experimental data, preference is given to the mathematical model Dura Crete. Life cycles for the main degradation processes in concrete and reinforcement, periods of initiation and propagation of corrosion are considered. Particular attention is paid to the influence of environmental factors and the quality of concrete on the kinetics of chloride penetration and movement of the carbonization front. Formulated limit state design reinforced concrete durability in chloride attacks and carbonation. The basic provisions of the method of calculating the durability of reinforced concrete structures, based on the use of the reliability coefficient for the service life. The practical assessment of service life of reinforced concrete elements taking into account stochastic processes in concrete and reinforcement is made. Verification of the model reliability is performed. For all those interested in the issues of building materials and processes occurring in them.

scholarly journals Quantitative Design Methods for Protection Against Corrosion of Reinforced Concrete Structures During Various Stages of their Life Cycle

2020 ◽  
Vol 28 (3) ◽  
pp. 8-12
Author(s):  
Mykola Savytskyi ◽  
Stanislav Uncik ◽  
Olexandr Bardakh ◽  
Andriy Savytskyi ◽  
Tetiana Shevchenko ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Design Methods ◽  
Economic Feasibility ◽  
National Standards ◽  
Reinforced Concrete Structures ◽  
Quantitative Methodology ◽  
Aggressive Environment ◽  
Quantitative Design ◽  
Kinetics Of

AbstractThere are large amounts of reinforced concrete structures that have undergone damage from corrosion at their operational stage. The Eurocodes and national standards do not contain any guidelines for designing primary protection and repair systems for reinforced concrete structures. Our research shows the economic feasibility of designing reinforced concrete structures that can interact with an aggressive environment, taking into account the kinetics of concrete corrosion. Optimal design methods can be used to obtain the most economical solutions. We have developed a quantitative methodology for the design of the primary protection of reinforced concrete structures.

scholarly journals Modern cement-based waterproofings for hydraulic structures protection

2020 ◽  
pp. 175-185
Author(s):  
O. V. Kovalenko
Keyword(s):  
Water Management ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Operational Reliability ◽  
Water Filtration ◽  
Hydraulic Structures ◽  
Reinforced Concrete Structures ◽  
Two Component ◽  
Polymer Latex ◽  
Selection Of

Hydrotechnical structures of water management and land reclamation complex from the moment of commissioning are subject to aggressive environmental effects: hydrostatic water pressure, alternating freezing and thawing, moistening and drying, corrosive action of salts dissolved in water, dynamic action of ice. The trouble-free operation of structures with long-term aggressive environmental factors is possible only in the case of providing their protection (reinforcement) with effective insulating, anticorrosive, high-strength, wear-resistant and cavitation-resistant composite materials. Waterproofing coatings, which arrange on the surface of reinforced concrete structures, plays an important role in ensuring operational reliability and durability of hydraulic structures. Having rather low cost of waterproofing coatings as compared to the cost of structures the fate of their responsibility in terms of ensuring the durability and operational reliability of the structures is high enough. Waterproofing coatings serve as a barrier to an aggressive environment and thus protect structures from destruction. Notwithstanding the importance of waterproofing protection, this issue is not given due attention today. Therefore, filtration of water through the structures of water-reclamation facilities is a common phenomenon. Water filtration through damaged concrete of hydraulic structures causes dissolution and leaching of water with calcium hydroxide (leaching), which further causes the decomposition of other components of the cement stone and leads to the dilution of the concrete structure and to the strengthening of drip filtration. Drip filtration increases over time, then jet filtration develops, which can lead to complete destruction of the structure. Therefore, providing waterproofing protection of structures is an important engineering task in their construction and operation. One of the determining factors for the effectiveness of waterproofing is the right selection of material. Traditional waterproofing materials on a bituminous basis have insufficient physical-mechanical properties and durability. However, modern technologies of waterproofing protection of concrete and reinforced concrete structures are based on the use of effective composite materials with high physical, mechanical and protective properties. Depending on the type of binder, waterproofing materials can be based on bitumen, bituminous-mineral, bitumen-polymer, coal, polymer compositions, as well as on the basis of cements and polymer cements. The selection of a waterproofing material should be made taking into account the specifics of the operating environment and the conditions of use. The most common in the construction of gluing roll materials on a bituminous basis can only partially satisfy the need for hydraulic engineering, as for the waterproofing of hydraulic structures. There are high requirements with regard to the aggressiveness of the environment and their low repairsability. The most promising for use in the technology of arrangement of waterproofing coatings on concrete and reinforced concrete structures of hydraulic engineering facilities of water management and reclamation complex are polymer cement mixtures, binders in which are Portland cement modified with polymer latex dispersion powder (for two-component). Creation of effective polymer cement waterproofing compositions is based on optimization of the ratio of interpenetrating meshes of polymers and crystal matrix hydrates. Modification of cement systems by polymers allows to increase adhesion and deformation characteristics, fracture resistance and corrosion resistance of polymer cement composites. Depending on the components included in the mixture, waterproofing coatings may be rigid or elastic. Rigid formulations are a water-mixed, dry mixture that includes a vinyl acetate copolymer and designed for waterproofing concrete and reinforced concrete structures with low water filtration. Elastic waterproofing materials are usually two-component. These materials are used for waterproofing structures that are susceptible to deformation, as well as surfaces with a high degree of water filtration and where cracks up to 1 mm are formed. Elastic two-component formulations are dry mixtures with the addition of redispersible polymer powders. They consist of two components: a dry mixture of modified fine cement and aqueous latex polymer, usually acrylic. The content of polymer latex in the mixture has a significant effect on the rheological properties of polymer-cement mixtures and on the physical and mechanical properties of waterproofing coatings made of them. Thus, the introduction of a redispersible polymer powder Axilat L 8262 in a waterproofing mixture in the amount of up to 10% by weight of cement increases the mobility of the mixture from 3,2 to 8,0 cm, increases the adhesive strength of the coating to concrete from 0,45 to 1,95 MPa, increases its bending strength from 6,9 to 7,9 MPa, reduces its water absorption in 24 hours from 7,02% to 0,35% .  

scholarly journals Study of Concrete under Combined Action of Aggressive Environment and Long-Term Loading

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6612
Author(s):  
Yaroslav Blikharskyy ◽  
Jacek Selejdak ◽  
Nadiia Kopiika ◽  
Rostyslav Vashkevych
Keyword(s):  
Reinforced Concrete ◽  
Concrete Strength ◽  
Aggressive Medium ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Corrosion Damage ◽  
Simultaneous Action ◽  
Reinforced Concrete Structures ◽  
Cross Sectional ◽  
Aggressive Environment

A significant part of reinforced concrete structures is subjected to intensive environmental impact during operation. This can cause local destruction and failure of buildings if obligatory measures are not taken to protect them from corrosion. This is especially true for industrial buildings, where the environment could be contaminated with aggressive products or waste. An important issue is the development of methods for calculating the load-bearing capacity and serviceability of reinforced concrete structures with corrosion damage. The main reason for this is the necessity to determine the durability and reliability of buildings and structures and the estimation of their safe operation time. As corrosion damages of concrete are a critical issue, more detailed experimental studies are needed. This paper presents experimental studies of concrete prisms under the simultaneous action of an aggressive environment and a constant level of compressive force. In total, 32 prisms under different loading conditions and in different aggressive medium were tested. Samples were divided in series, for which different load levels were chosen (0.25fck, 0.35fck, 0.45fck). Additionally, control samples in the air and immersed in water were tested. During the experiment, different parameters were monitored and recorded: decrease of cross-sectional size, the temperature and environmental humidity. Results of the study showed that destruction occurred due to the presence of corrosion damages of concrete and a reduction of the cross-sectional area. The stresses in the concrete at the destruction stage were less than the value of the prism strength by 10–12%. It was established that along the contour of the section, there is a partially degraded layer of concrete of 1.5–3.7 mm thickness, with corrosion microcracks and corrosion products. Additionally, experimental and theoretical diagrams of concrete with corrosion damages were obtained and compared. The ultimate deformations of concrete with corrosion damage, which correspond to the prismatic strength of concrete, in comparison with undamaged concrete were lower by 11–18%. Therefore, the concrete strength is decreased during exploitation under loading in an aggressive environment, which needs to be taken into account during calculations.

The Development of Coating Systems Based on Alkali Activated Slag for Protecting Reinforced Concrete Structures

2016 ◽  
Vol 865 ◽  
pp. 87-94
Author(s):  
Ámos Dufka ◽  
Tomáš Melichar ◽  
Jiří Bydžovský
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Slag Coating ◽  
Alkali Activated Slag ◽  
Aggressive Environment ◽  
Activated Slag ◽  
Alkali Activated

Theme of the article is the development of coating systems based on alkali activated stag intended for protection of reinforced concrete constructions exposed to chemically aggressive environments. At present mainly polymer based secondary protections are used for this purpose. The coating systems based on alkali activated slag have potential to surpass these generally applied types of secondary protections in many aspects. For instance for constructions exposed to synergic actuation of chemically aggressive environment and increased temperatures. Findings obtained from alkali activated slag coating exposed to selected aggressive environment types for six months are presented in this article.

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