scholarly journals ASSESSMENT OF THE DEPTH AND RATE OF CORROSION IN STEEL REINFORCEMENT OF REINFORCED CONCRETE CULVERTS

2020 ◽  
Author(s):  
Alexandr Vasiliev ◽  
Svetlana Daškevič
Keyword(s):  
Reinforced Concrete ◽  
Protective Layer ◽  
Corrosion Damage ◽  
Steel Reinforcement ◽  
Operating Conditions ◽  
Protective Properties ◽  
Open Atmosphere ◽  
Concrete Elements ◽  
Corrosion State

Based on the results of many research years on concrete carbonisation: both immediately after manufacture (using heat-moisture treatment) and in reinforced concrete elements operated for the periods of various length (in an open atmosphere); the effect of carbonisation on the change in the protective properties of concrete in relation to steel reinforcement; for determination of the dependence of the corrosion state of steel reinforcement on the degree of concrete carbonisation in the area of steel reinforcement; the obtained regression dependences of the change (by time in the cross section) of the degree of concrete carbonisation of various classes in strength, – the analysis of the time of the onset of the boundary values of the degrees of concrete carbonisation (strength classes C12/15–C30/37) for the operating conditions of the open atmosphere was performed. Based on it, the regression dependences of the time variation of the depth of corrosion damage of steel reinforcement were construed (for fixed thicknesses of the concrete protective layer). The obtained nature of dependences made it possible to offer, in a general form, the regression dependences of the depth of corrosion damage and corrosion rate of steel reinforcement for concretes (strength classes C12/15–C30/37) for operating conditions in open atmosphere.

scholarly journals ОЦЕНКА СКОРОСТИ ДЕГРАДАЦИИ ЖЕЛЕЗОБЕТОННЫХ ВОДОПРОПУСКНЫХ ТРУБ

World Science ◽  
2018 ◽  
Vol 2 (7(35)) ◽  
pp. 15-22
Author(s):  
Васильев А. А. ◽  
Дашкевич С. В
Keyword(s):  
Average Rate ◽  
Protective Layer ◽  
Corrosion Damage ◽  
Analytical Form ◽  
Steel Reinforcement ◽  
Design Stage ◽  
Operational Parameters ◽  
Protective Properties ◽  
Formation Of Cracks

Based on a long-term studies and research: the changes of carbonization in time along the cross-section of concrete of various classes in strengths; its effect on the change of the protective properties of concrete in relation to steel reinforcement; the conditions of steel reinforcement and concrete of the protective layer,- the graphical dependences have been obtained, allowing to estimate and predict the depth of corrosion damage of steel reinforcement; the average rate of its corrosion, the time of the onset critical damage to steel reinforcement and the formation of cracks with development of critical width from the thickness of protective layer for concrete of various classes on the strength, which are operated in conditions of open atmosphere.The nature of the dependencies obtained makes it possible to obtain in an analytical form the regression dependencies of the change in corrosion rate of steel reinforcement in carbonized concrete on various technological and operational parameters. That will allow much more objective predictions of the durability of reinforced concrete water pipes (culverts) much more objectively, both at the design stage and during operation.

scholarly journals Phosphate coatings as a way to protect steel reinforcement from corrosion

2019 ◽  
Vol 298 ◽  
pp. 00126 ◽  
Author(s):  
Sergey Fedosov ◽  
Varvara Roumyantseva ◽  
Viktoriya Konovalova
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Protective Properties ◽  
Phosphate Coatings ◽  
Mass Transfer Mechanism ◽  
Reinforced Steel ◽  
Kinetics Of

Phosphate coatings are successfully applied as a method of protecting steel products and structures from corrosion. Phosphate coatings mechanically prevent the entry of aggressive particles, such as chloride ions, to the surface of steel reinforcement. The parameters of corrosion rate of reinforcing steel in aggressive environment are determined by graphical method. The analysis of corrosion diagrams allows us to judge the effect of protective phosphate coatings on the kinetics of the corrosion process of steel reinforcement in environments of varying degrees of aggressiveness. The tests of the protective properties of phosphate coatings by contact corrosion method show that films with a finer crystal structure, as in modified phosphate coatings, are more resistant to anodic dissolution of steel. In parallel to determination of iron ions content in solutions the potential of steel reinforcement samples was measured. In samples protected by phosphate films, the potential change is not as sharp as in samples without coating, and the “dilution” of steel is slower. The study of anodic behavior of steel reinforcement of reinforced concrete, experimental study of the mass transfer mechanism of electrolyte supply to the surface of reinforced steel allow to develop practical recommendations to improve corrosion resistance and ensure the durability of reinforced concrete building materials.

Bearing Capacity Of Centrally Compressed Reinforced Concrete Elements Corrosion-Damaged As A Result Of Fire Exposure

2019 ◽  
pp. 35-39
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Protective Layer ◽  
Temperature Fields ◽  
Reinforced Concrete Column ◽  
The Cross ◽  
Concrete Elements ◽  
Technical Calculation

Determination of the bearing capacity of the elements damaged as a result of fire effect depends on the accuracy of the thermo-technical calculation. After this calculation, the distribution of the temperature field over the cross section of the element and the strength characteristics depending on it are determined. The temperature distribution over the cross section of the element depends on such parameters as heat capacity and thermal conductivity of parts of the section, the spatial position of the structure, its humidity. As part of this work, heat engineering calculations of the cross section of the reinforced concrete column were performed with various options of the cross section - with and without a protective layer, taking into account the thermal performance of all cross section components (reinforcement, concrete and corrosion) and excluding corrosion and reinforcement. Based on the obtained temperature fields, the bearing capacity and its percentage ratio were calculated. The main conclusion is that the bearing capacity of the centrally compressed corrosion-damaged elements is significantly influenced by the factor of separation of the protective layer of concrete, as well as thermal-technical characteristics of materials.

scholarly journals Damage Assessment of Reinforced Concrete Elements Due to Corrosion Effect Using Dynamic Parameters: A Review

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 425
Author(s):  
Ivan Duvnjak ◽  
Ivan Klepo ◽  
Marijana Serdar ◽  
Domagoj Damjanović
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Protective Layer ◽  
Continuous System ◽  
Future Research ◽  
Reinforced Concrete Structures ◽  
Dynamic Parameters ◽  
Determination Methods ◽  
Concrete Elements

Corrosion of reinforcement is one of the main problems related to the durability of reinforced concrete structures. This can cause cracks and a separation of the protective layer, as well as reducing strength and structural stiffness, which can result in numerous human casualties. Visual inspection is a standard method of assessing the condition of reinforced concrete structures whose limitations, such as time, interpretability, accessibility, etc., may affect its effectiveness. Therefore, damage determination methods based on dynamic parameters are becoming more and more prominent in the assessment of damage to reinforced concrete structures. The aim of this paper is to review the literature regarding the determination of corrosion of reinforcement by methods based on dynamic parameters, and to identify future research to develop a method that would detect corrosion problems in time through a continuous system of structural health monitoring.

scholarly journals Analyzing of Coatings on Steel - Reinforced Concrete Elements by Mobile NMR

2016 ◽  
Vol 62 (1) ◽  
pp. 65-82 ◽  
Author(s):  
J. Orlowsky
Keyword(s):  
Reinforced Concrete ◽  
Potential Effect ◽  
Building Site ◽  
Steel Reinforced Concrete ◽  
Mobile Nmr ◽  
The Individual ◽  
First Time ◽  
Concrete Elements ◽  
Non Destructive

Abstract A large number of infrastructural concrete buildings are protected against aggressive environments by coating systems. The functionality of these coating systems is mainly affected by the composition and thickness of the individual polymeric layers. For the first time ever, a mobile nuclear magnetic resonance (NMR) sensor allows a non-destructive determination of these important parameters on the building site. However, before this technique can be used on steel-reinforced concrete elements, the potential effect of the reinforcement on the measurement, i.e. the NMR signal, needs to be studied. The results show a shift of the NMR profile as well as an increase of the signals amplitude in the case of the reinforced samples, while calculating the thickness of concrete coating leading to identical results.

scholarly journals TO DETERMINATION OF THE CRACKING MOMENT FOR BENDING REINFORCED CONCRETE ELEMENTS WITH ACCOUNT OF PLASTIC DEFORMATIONS OF CONCRETE IN THE TENSION AREA

2018 ◽  
Vol 3 (3) ◽  
pp. 30-38
Author(s):  
О.В. Радайкин ◽  
Oleg Radaykin
Keyword(s):  
Reinforced Concrete ◽  
Deformation Model ◽  
Conventional Concrete ◽  
Class A ◽  
Standard Calculation ◽  
Plasticity Coefficient ◽  
Concrete Elements ◽  
Nonlinear Deformation Model ◽  
Good Agreement

At the standard calculation of the cracking moment for bending reinforced concrete elements the plasticity coefficient γ is normally used, which according to SP 63.13330.2012 is 35% less than in the old SNiP 2.03.01-84*. The question arises, what is the reason for such a noticeable difference and which of the methods gives more reliable results? This article seeks to answer this question. For this purpose the physical meaning of the coefficient γ was considered in detail, with the usage of a nonlinear deformation model of a normal section. A calculation formula for γ depending on an element’s reinforcement degree was obtained, which is valid for conventional concrete of B15-B35 class. A comparison of the calculated cracking moment according to the proposed method with experiments by the other authors was carried out. A good agreement of results was observed.

scholarly journals Determination of distribution of heat-conducting material concentration in protective layer of thermal protection system panel

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1025-1034
Author(s):  
Lukasz Brodzik ◽  
Andrzej Frackowiak
Keyword(s):  
Thermal Protection ◽  
Protective Layer ◽  
Heat Conducting ◽  
Conducting Material ◽  
Protective Properties ◽  
Conductive Material ◽  
Time Extension ◽  
Heating Up ◽  
Dope Concentration

Paper presents the problem of heating the damaged insulation of an orbiter. Changes of the insulation?s thermal properties, made by adding conductive material of high value of specific heat in a form of a dope to the protective layer, were examined. An iterative algorithm determining a variable of dope concentration in the material was developed. Insulating material LI900 was used for calculations. Determination of distribution of conductive material concentration was made for materials which, after verification, demonstrated the most beneficial effect on protective properties of the modified insulation layer. Change of properties was to enable time extension of the LI900 insulation tile heating up to the maximal temperature and, additionally, to lowering this temperature.

scholarly journals COMBINED EFFECT OF CARBONATION AND CHLORIDE AGGRESSION: DEG-RADATION OF REINFORCED CONCRETE STRUCTURES

2018 ◽  
Author(s):  
L.V. KIM ◽  
E.E. SHALYI ◽  
S.N. LEONOVICH ◽  
N.A. BUDREVICH
Keyword(s):  
Reinforced Concrete ◽  
Ph Value ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Protective Layer ◽  
Sharp Decrease ◽  
Threshold Concentration ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structures ◽  
Cross Sectional

Corrosion reinforcement marine hydraulic structures due to chloride aggression and carbonization of concrete leads to a sharp decrease in the safety of the structure. The steel reinforcement will be subjected to a so-called depassivation process, once the chloride concentration on surface exceeds a certain threshold concentration, or the pH value in the protective layer of concrete decreases to a threshold value due to carbonation. Electrochemical reactions begin to occur with the formation of corrosion products with the penetration of oxygen on the steel reinforcement surface. This leads to cracking of the protective layer of concrete. It should also be taken into account that, due to corrosion mechanisms, the cross-sectional area of the reinforcement also decreases. The article suggests a method for predicting the complex degradation of reinforced concrete structures, taking into account various mechanisms of corrosion wear, which will allow developing effective ways to improve the durability and maintainability of structures operated in the marine environment.

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