Hollow-Core Slabs with Reinforcement in the Support Zone

2019 ◽  
pp. 50-53
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Support Surface ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Hollow Core ◽  
Support Zone ◽  
Main Disadvantage ◽  
Foreign Enterprises

The wide use of hollow-core slabs in the construction of industrial and civil buildings is promoted by technical characteristics in the form of saving cement consumption up to 30-40 %, reducing the consumption of reinforcing steel 10 times and more, the overlap of spans up to 15-20 m. In Russia there are more than 200 plants of reinforced concrete structures producing hollow-core slabs. The technology of their production is different - from bench technology using pre-stressed forms, to the manufacture of plates on the "tracks". The main disadvantage of the use of manufactured slabs at domestic and foreign enterprises is their ability to perceive only "beam" loads. Meanwhile, giving these products the functions of operation on the console loads can significantly expand the possibility of using these effective structures. The article provides examples of amplification of hollow- core slabs operating on the console loads. Such slabs make it possible with the help of one product to create a support surface for balconies, loggias, bay windows, consoles.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

scholarly journals Corrosion protection of reinforcing steel reinforced concrete structures of transport structures

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander Bulkov ◽  
Michail Baev ◽  
Igor Ovchinnikov
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Protection ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
High Strength ◽  
Curing Temperature ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Steel Reinforced Concrete ◽  
Advantages And Disadvantages

The influence of reinforcing steel corrosion on the durability of reinforced concrete structures of transport structures and the degree of knowledge of this problem is considered. It is specified that the protection of reinforcing steel from corrosion is not able to completely replace the correct design and use of high-strength concrete. But it is able to extend the life of reinforced concrete structures. It is noted that corrosion of the reinforcement leads to a decrease in the structural strength due to wear and tear and by a third of the period of operation of reinforced concrete structures, as a result of which transport structures collapse. As an example of the detrimental effect of corrosion of reinforcing steel on the durability of transport structures, examples of accidents of bridges and overpasses caused by this type of corrosion are given. As a result, a conclusion is drawn on the advisability of ensuring a sufficient level of corrosion protection of reinforcing steel to achieve the required durability of reinforced concrete structures of transport structures. The types and causes of corrosion processes in reinforcing steel reinforced concrete structures are described. The compositions and technologies of anticorrosive protection are examined and analyzed. Comparison of the compositions of anticorrosive protection of reinforced concrete structures is carried out according to the following criteria: consumption, density, viability, curing temperature and the number of components of the composition. A comparison of anti-corrosion protection technologies is carried out on the basis of the following indicators: line dimensions, productivity and consumption of energy resources. A comparison is also made of the cost of using various anti-corrosion protection technologies. Based on the data obtained, the advantages and disadvantages of the considered compositions and technologies of corrosion protection are determined. As a result, the most effective and technologically advanced method of corrosion protection of steel reinforcement of reinforced concrete structures of transport structures is selected.

scholarly journals Experimental study of the influence of crack width due to corrosion behaviour using different measurement methods and different exposures

2019 ◽  
Vol 289 ◽  
pp. 08005
Author(s):  
Martin Schneider ◽  
Georg Gardener
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Corrosion Behaviour ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Surface Corrosion ◽  
Potential Mapping

Corrosion of reinforcing steel has a great influence in reducing the lifetime of concrete structures; Carbonation of the concrete pore solution causes surface corrosion on the steel and diffusion of chloride ions through the capillary system of the concrete cover causes pitting corrosion on the steel surface. Corrosion of metals is highly dependent on the environmental conditions. Exposure to chloride ions can be critical to the service life of reinforced concrete structures. The durability of reinforced concrete structures exposed to deicing salt or marine environments can be affected by impact of chloride ions. Detection methods for the rate of corrosion of non-destructive and destructive procedures were analysed. The potential mapping applied on the concrete surface was discussed as a standard method for corrosion detection and will be explained in detail including the application boundaries of the method. It is assumed that the corrosion behaviour of reinforcing steel depends on crack widths. To analyse that, 8 coated and 8 uncoated test samples with different concrete strength classes were used. The concrete objects were exposed to a 3% sodium chloride solution. The corrosion behaviour of reinforcing steel is analysed by using potential mapping with different reference electrodes (Ag/AgCl and Cu/CuSO4). The results show a significant correlation between crack size and protection system on the surface. The maximum crack width with a low indication of corrosion was found to be 0.1 mm.

scholarly journals Detection of Reinforcement Corrosion in Reinforced Concrete Structures by Potential Mapping: Theory and Practice

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Gino Ebell ◽  
Andreas Burkert ◽  
Jürgen Mietz
Keyword(s):  
Reinforced Concrete ◽  
Influencing Factors ◽  
Stress Measurement ◽  
Concrete Structures ◽  
German Society ◽  
Theory And Practice ◽  
Test Method ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Potential Mapping

Electrochemical potential mapping according to guideline B3 of DGZfP (German Society for Nondestructive Testing) is a recognized technique for the localization of corroding reinforcing steels. In reinforced concrete structures the measured potentials are not necessarily directly linked to the corrosion likelihood of the reinforcing steel. The measured values may be significantly affected, different from, e.g., stress measurement, by different influences on the potential formation at the phase boundary metal/concrete itself as well as the acquisition procedure. Due to the complexity of influencing factors there is a risk that the results are misinterpreted. Therefore, in a training concept firstly the theoretical basics of the test method should be imparted. Then, frequently occurring practical situations of various influencing factors will be made accessible to the participants by a model object specially designed for this purpose. The aim is to impart profound knowledge concerning the characteristics of potential mapping for detecting corrosion of reinforcing steel in order to apply this technique in practice as reliable and economical test method.

Effect of Anodic and Cathodic Chloride Contents on the Macrocell Corrosion and Polarization Behavior of Reinforcing Steel

2016 ◽  
Vol 22 ◽  
pp. 45-58 ◽  
Author(s):  
Zhong Lu Cao ◽  
Hao Yu Chen ◽  
Lian Yu Wei ◽  
Makoto Hibino
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Chloride Content ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Anodic Reaction ◽  
Polarization Behavior ◽  
Mixed Control ◽  
Cement Mortars ◽  
Macrocell Corrosion

The effect of anodic and cathodic chloride contents on the macrocell corrosion and polarization behavior of reinforcing steel embedded in cement mortars were investigated and clarified. The results indicated that the higher cathodic chloride content could accelerate the cathodic reaction of cathode and make the controlling mode of macrocell corrosion changed from cathodic control to mixed control or anodic control. The higher anodic chloride content could accelerate the anodic reaction of anode and make the macrocell corrosion more controlled by cathode. These results will provide a guide to inhibiting the macrocell corrosion of reinforcing steel in concrete, which are not only useful for engineers to design and construct the new marine reinforced concrete structures, but also are helpful for engineers to repair or rehabilitate the existing chloride contaminated reinforced concrete structures, in the condition of avoiding the adverse effect of macrocell corrosion induced by the non-uniform distribution of anodic and cathodic chloride.

scholarly journals Investigation of the relationship between the strength limit and the long time fatigue of steel reinforcements of reinforced concrete structures

2021 ◽  
pp. 28-40
Author(s):  
Denys Chernyshev ◽  
Yulia Makarenko ◽  
Tetiana Khomutetska ◽  
Valeriy Makarenko
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Hydrogen Content ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Term Operation ◽  
Strength Limit

The results of experimental studies have shown a strong effect of diffusion hydrogen on the static and cyclic parameters of crack resistance of reinforcing steel. It was found that with increasing flooding, especially when the hydrogen content exceeds 5 cm3/100g, both static strength and long-term strength (fatigue) decrease sharply. Moreover, these areas of hydrogen solution in reinforcing steel are characterized by a viscous nature of fracture, while for heavily flooded reinforcement (from 5 to 12 cm3/100g) is characterized by brittle fracture by the mechanism of microcracking in the hardened (martensite or troostite structure). The analysis of the obtained experimental results allowed to determine the optimal hydrogen content in the reinforcing steel (3…5 cm3/100g), the excess of which can cause a decrease in the crack resistance of the reinforcement during long-term operation, especially in corrosive environments. The mechanism of hydrogen influence on crack resistance of metal at static and alternating loading which consists in diffusion and dislocation movement of hydrogen in structure of a reinforcing core that as a result that causes strong flooding of steel and its embrittlement is offered. It is established that carbon and low-alloy sieves, which are characterized by ferritic-pearlitic and sorbitol structure provide high resistance, especially to long-term fatigue, and the transition to steels with a structure of martensite or tempered (transient structure of bainite) structure of bainite sharply reduces reinforcing steel, which makes it impossible to use in the manufacture of reinforcement involved in reinforced concrete structures designed for long-term operation (more than 50…60 years). Thus, the obtained diagram can be recommended to designers of reinforced concrete structures for hydraulic purposes, as it greatly facilitates the reasonable choice of reinforcement in the development of reinforced concrete structures for responsible and long-term use.

INFLUENCE OF CONCRETE COMPOSITION ON THE CORROSIVE STATE OF THE STEEL ARMATURES AND DURABILITY OF REINFORCED CONCRETE STRUCTURES

2019 ◽  
pp. 33-39
Author(s):  
Petro Koval ◽  
Vladimir Zelenovskiy
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
The State ◽  
Test Method ◽  
Design Stage ◽  
Reinforced Concrete Structures ◽  
Building Structures ◽  
Reinforcing Steel ◽  
Concrete Composition ◽  
Corrosion State

The influence of the composition of the concrete mixture on the state of reinforcing steel as the main problem of corrosion of reinforced concrete structures is considered. The main attention is paid to the need for individual and mandatory consideration of the influence of the properties of additives to concrete on the passivation of reinforcing steel. The purpose of conducting studies to determine the effect of concrete composition on the state of reinforcing steel is to analyze the causes of corrosion of reinforcement, determine the influence of the environment, apply appropriate prevention of this phenomenon and use methods to determine the corrosion state at the design stage of building structures for which reinforced concrete is used. The composition of concrete, in addition to the standard set in various quantitative combinations (cement, gravel, sand, water) today it is advisable to use special additives. Due to their correct and proportional application, you can create a mixture with significantly improved characteristics: with increased frost resistance, strength, durability, with accelerated or delayed setting of the mixture, etc. Nevertheless, you should not forget that the individuality of the composition of additives could affect the ability of concrete to passivate reinforcing steel. It is possible to eliminate the possibility of reducing the passivation of concrete by testing reinforced concrete samples for its protective properties in relation to the reinforcement. The test method is based on the passivation of reinforcing steel in an alkaline environment and consists in evaluating the protective effect of a sample of concrete in relation to a sample of steel reinforcement by comparing data obtained with a change in potential depending on changes in the density of electric current passing through the sample. The issue of quality and durability of reinforced concrete structures, both technically and economically, is attracting increasing attention of builders. It is obvious that in most cases an increase in the initial cost of manufacturing the structure and its reliable protection is economically justified, if this allows reducing the number and cost of repairs during operation. Keywords: reinforcement, corrosion, concrete, reinforced concrete, concrete additive, concrete composition, corrosion state of reinforcement, durability of reinforced concrete structures.

scholarly journals Strength Calculation Features and Tests Results on Bearing Capacity and Operational Serviceability of Hollow-Core Floor Slabs of Formwork-Free Shaping in Seismic Areas

2020 ◽  
Vol 9 (1) ◽  
pp. 2219-2225
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Construction Industry ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforced Concrete Structures ◽  
Hollow Core ◽  
Wide Range

The technology of manufacturing reinforced concrete structures of long-line systems of formwork-free shaping is widely used lately in construction industry in many countries. Using this technology, industrial construction can be carried out in accordance with the requirements of modern regulatory documents that allow projects to be developed individually, and production can be reoriented in a very short time in accordance with emerging needs. This means that on the same production line it is possible to produce various structural elements of buildings and structures. Also, this technology allows the production of structures according to a wide range of products that meet operational requirements, and increases the possibility of their use in design of buildings and structures with various architectural, planning and structural decisions. Prestressed hollow-core slabs of formwork-free shaping reinforced with high-strength wire reinforcement are widely used due to the simplicity of construction and their relatively low cost, as well as their high bearing capacity, large spans and better quality. The problem of their introduction into construction industry of Uzbekistan is that the issues of designing, manufacturing and using them in construction have not been studied. Besides, the production technology of such slabs is mostly associated with the construction in non-seismic areas, and the country does not have an appropriate regulatory framework for the possibility of slab designing and production. The aim of the study is to assess the strength and serviceability of hollow-core slabs of formwork-free shaping, designed on the basis of the proposed structural solution of the slab cross section and intended for construction in seismic areas. Therefor the issues of optimizing the main reinforcement consumption (prestressed high-strength wire reinforcement) at class B30 concrete strength without using the non-stressed reinforcement (reinforcing products) for the product range under consideration were addressed. Theoretical and constructive solutions of the slabs were developed in accordance with the standard requirements of Uzbekistan KMK 2.03.01-96 “Concrete and reinforced concrete structures”, KMK 2.01.03 “Construction in seismic areas” and considering the Euronorm EN 1168-2005 requirements “Precast concrete. Hollow-core slabs”.

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