scholarly journals New warning sensors to detect corrosion risk in reinforced concrete

2019 ◽  
Vol 289 ◽  
pp. 06002
Author(s):  
Mahdi Khadra ◽  
Elisabeth Marie-Victoire ◽  
Myriam Bouichou ◽  
Christian Crémona ◽  
Stéphanie Vildaer
Keyword(s):  
Reinforced Concrete ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Cultural Value ◽  
Original Material ◽  
Reinforcing Bars ◽  
First Results ◽  
Corrosion Risk ◽  
Deterioration Mechanism ◽  
Different Depths

Corrosion is the most frequent but also the most deleterious deterioration mechanism affecting reinforced concrete. In addition to the economic impact of the repair works, for historical concrete structures, corrosion can generate irreversible losses of original material of great cultural value. If the usual non-destructive electrochemical methods have highlighted their efficiency in evaluating on-going corrosion activity, they also have pointed out their drawbacks for accurate extrapolation and prevention. To prevent the corrosion phenomenon, by detecting the penetration of aggressive agents, a new warning sensor system has been developed. The principle of the technique is to embed thin metallic sheets (called orphan blades) in the concrete cover, at different distances from the surface to the reinforcing bars. Then the corrosion of those very reactive orphan blades is followed during the propagation of the carbonation front and/or the penetration of chloride ions using stimulated infrared thermography. The corrosion of the sensors at different depths is indicative of the ingress speed of the front and can alert about the risk of corrosion of reinforcing bars in the concrete. The purpose of this study is to present this new technique and the first results obtained in the laboratory on corroded and non-corroded sensors.

scholarly journals Temporal analysis of the performance of an elevated concrete tank considering the corrosion of the steel reinforcement

2021 ◽  
Vol 15 (56) ◽  
pp. 94-114
Author(s):  
Hocine Hammoum ◽  
Nassima Miloudi ◽  
Karima Bouzelha ◽  
Younes Aoues ◽  
Ouali Amiri
Keyword(s):  
Reinforced Concrete ◽  
Pitting Corrosion ◽  
Temporal Analysis ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Atmospheric Conditions ◽  
Engineering Structures ◽  
Corrosion Risk ◽  
Concrete Tank ◽  
Loss Of Strength

Reinforced concrete water storage tanks are civil engineering structures subject to very aggressive atmospheric conditions that expose them to harmful corrosion risk. This dangerous phenomenon caused by the penetration of chloride ions causes pitting corrosion and leads to the reduction of the section of the reinforcements and consequently to the loss of strength and the structure performance. In this study, we are interested in analyzing the performance of an elevated storage tank, taking into account the corrosion of the reinforcements subjected to tensile stress, by considering environments with different rates of aggressiveness. A method based on Housner's model is used to evaluate the tension stresses in the reinforced concrete (RC) pedestal (supporting system) of the tank, subjected to the seismic actions. A pitting corrosion model is developed in order to determine the evolution in time of the reinforcements section in different environments. Several parameters influencing corrosion are taken into account, such as concrete cover and the concentration of chlorides ions.

Numerical Interpretation of Bond Between Steel and Concrete in Presence of Corrosion and Cyclic Action

2009 ◽  
Vol 417-418 ◽  
pp. 349-352 ◽  
Author(s):  
Luca Giordano ◽  
Giuseppe Mancini ◽  
Francesco Tondolo
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Stress Transfer ◽  
Experimental Tests ◽  
Radial Pressure ◽  
Mechanical Action ◽  
Concrete Cover ◽  
Reinforcing Bars ◽  
Cyclic Action ◽  
Bond Slip

Bond between steel and concrete in reinforced concrete structures plays a fundamental role. The stress transfer mechanism depends on the condition of the contact surface between the two materials, the mechanical characteristics of concrete near the rebar and on the available level of confinement. Corrosion of reinforcing bars in concrete structures modifies those three factors. Because of corrosion, on the rebar surface a granular oxide layer is present and with its expansion it generates a significant radial pressure; consequently tensile stresses grow till cracking of the concrete cover with a subsequent reduction of the confinement effect. Moreover the presence of a mechanical action modifies the resisting mechanism producing an increasing damage. In this study, a model is presented for the numerical simulation of experimental tests on r.c. ties subjected to mechanical action; furthermore some considerations on reinforced concrete ties subjected also to corrosion effect are reported. From those analyses it is possible to estimate a modified bond-slip law between the reinforcing bars and the concrete, in order to take into account the level of damage.

APPLICATION OF INNOVATIVE MATERIALS IN PRECAST CONCRETE STRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Klaus Holschemacher
Keyword(s):  
Reinforced Concrete ◽  
Construction Industry ◽  
Precast Concrete ◽  
Cementitious Materials ◽  
Concrete Cover ◽  
Fiber Reinforced Concrete ◽  
Textile Reinforced Concrete ◽  
Construction Methods ◽  
Corrosion Risk ◽  
Innovative Materials

Construction industry contributes essentially to Germany’s gross domestic product (GDP). In 2015 construction investments amounted around 300 billion Euro corresponding to a share of 10% of total GDP. Because of the essential importance of construction industry there are many activities aiming on reduction of construction costs and improvement of durability and sustainability. Recent tendencies in precast concrete industry include application of innovative materials like self-compacting concrete, fiber reinforced concrete, textile reinforced concrete, carbon concrete composite and strain hardening cementitious materials. The report describes the material developments and first applications for precast concrete members. By the application of non-metallic reinforcement, such as carbon meshes and carbon bars, there is no corrosion risk for the reinforcement resulting in an essentially lower concrete cover and depth of structural members. However, the use of carbon reinforcement requires new design concepts and new construction methods. By solving these problems there is a big chance for precast concrete industry to enhance their market share.

scholarly journals Bond Strengths of Geopolymer and Cement Concretes

2010 ◽  
Vol 69 ◽  
pp. 143-151 ◽  
Author(s):  
Prabir Sarker
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Geopolymer Concrete ◽  
Reinforcing Steel ◽  
Test Results ◽  
Reinforcing Bars ◽  
Pull Out ◽  
Bar Diameter

Geopolymer is an inorganic alumino-silicate product that shows good bonding properties. Geopolymer binders are used together with aggregates to produce geopolymer concrete which is an ideal building material for infrastructures. A by-product material such as fly ash is mixed together with an alkali to produce geopolymer. Current research on geopolymer concrete has shown potential of the material for construction of reinforced concrete structures. Structural performance of reinforced concrete depends on the bond between concrete and the reinforcing steel. Design provisions of reinforced concrete as a composite material are based on the bond strength between concrete and steel. Since geopolymer binder is chemically different from Ordinary Portland Cement (OPC) binder, it is necessary to understand the bond strength between geopolymer concrete and steel reinforcement for its application to reinforced concrete structures. Pull out test is commonly used to evaluate the bond strength between concrete and reinforcing steel. This paper describes the results of the pull out tests carried out to investigate the bond strength between fly ash based geopolymer concrete and steel reinforcing bars. Beam end specimens in accordance with the ASTM Standard A944 were used for the tests. In the experimental program, 24 geopolymer concrete and 24 OPC concrete specimens were tested for pull out. The concrete compressive strength varied from 25 to 55 MPa. The other test parameters were concrete cover and bar diameter. The reinforcing steel was 500 MPa steel deformed bars of 20 mm and 24 mm diameter. The concrete cover to bar diameter ratio varied from 1.71 to 3.62. It was found from the test results that the failure occurred by splitting of concrete in the region bonded with the steel bar, in both geopolymer and OPC concrete specimens. Comparison of the test results shows that geopolymer concrete has higher bond strength than OPC concrete. This suggests that the existing design equations for bond strength of OPC concrete with steel reinforcing bars can be conservatively used for calculation of bond strength of geopolymer concrete.

scholarly journals Condition assessment of selected reinforced concrete structural elements of the bus station in Kielce

2019 ◽  
Vol 284 ◽  
pp. 06007
Author(s):  
Paweł Tworzewski ◽  
Wioletta Raczkiewicz ◽  
Wioletta Grzmil ◽  
Przemysław Czapik
Keyword(s):  
Detection System ◽  
Thickness Distribution ◽  
Concrete Cover ◽  
Composition Analysis ◽  
Reinforcing Bars ◽  
X Ray Diffraction ◽  
Phenolphthalein Solution ◽  
Corrosion Risk ◽  
Cover Thickness ◽  
Non Destructive

The paper presents the results of the research aimed at assessing the condition of reinforcement and concrete cover in selected elements of the structure of the most recognizable structure in Kielce, i.e. PKS station, located at Czarnowska Street. Currently, demolition works are underway resulting from the planned modernization. The assessment of the corrosion risk of the reinforcement in the construction elements was carried out with the use of a semi-non-destructive electrochemical method. The use of this method made it possible to determine the probability of reinforcement corrosion in the selected areas and to estimate its rate. The protective properties of concrete cover were checked by the carbonation test (test using a 1% phenolphthalein solution) and phase composition analysis (X-ray diffraction analysis). In order to determine the position of the reinforcing bars and to estimate the concrete cover thickness distribution in the areas corresponding to the aforementioned measurements, ferromagnetic detection system was used.

scholarly journals Diagnostics of Concrete and Steel in Elements of an Historic Reinforced Concrete Structure

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 306
Author(s):  
Paweł Tworzewski ◽  
Wioletta Raczkiewicz ◽  
Przemysław Czapik ◽  
Justyna Tworzewska
Keyword(s):  
Reinforced Concrete ◽  
Detection System ◽  
Thickness Distribution ◽  
Pulse Method ◽  
Test Methods ◽  
Concrete Cover ◽  
Reinforced Concrete Structure ◽  
Corrosion Risk ◽  
Cover Thickness ◽  
Non Destructive

Existing buildings, especially historical buildings, require periodic or situational diagnostic tests. If a building is in use, advanced non-destructive or semi-destructive methods should be used. In the diagnosis of reinforced concrete structures, tests allowing to assess the condition of the reinforcement and concrete cover are particularly important. The article presents non-destructive and semi-destructive research methods that are used for such tests, as well as the results of tests performed for selected elements of a historic water tower structure. The assessment of the corrosion risk of the reinforcement was carried out with the use of a semi-destructive galvanostatic pulse method. The protective properties of the concrete cover were checked by the carbonation test and the phase analysis of the concrete. X-ray diffractometry and thermal analysis methods were used for this. In order to determine the position of the reinforcement and to estimate the concrete cover thickness distribution, a ferromagnetic detection system was used. The comprehensive application of several test methods allowed mutual verification of the results and the drawing of reliable conclusions. The results indicated a very poor state of the reinforcement, loss in the depth of cover and sulphate corrosion.

scholarly journals Effect of Concrete Addition of Selected Micro-fibers on the Reinforcing Bars Corrosion in the Reinforced Concrete Specimens

2016 ◽  
Vol 16 (3) ◽  
pp. 38-46 ◽  
Author(s):  
W. Raczkiewicz
Keyword(s):  
Reinforced Concrete ◽  
Electrochemical Corrosion ◽  
Pulse Method ◽  
Concrete Cover ◽  
Reinforcement Corrosion ◽  
Reinforcing Bars ◽  
Freezing And Thawing ◽  
Protective Properties ◽  
Concrete Elements ◽  
Non Destructive

Abstract The micro-fibers increase the consistency and uniformity of concrete, which can improve the protective properties of concrete cover and thus should reduce the corrosion of the reinforcement bars in the reinforced concrete elements. The article presents a study which main objective was to specify the effect on concrete mix the addition of steel or polypropylene micro-reinforcement fibers on the reinforcing bars corrosion process. The research included measuring the reinforcement corrosion progress caused by the chloride impact as well as cyclical freezing and thawing specimens test. To measure the electrochemical corrosion progress the non-destructive i.e. galvanostatic pulse method was used. The results were used to conduct a comparative analysis.

scholarly journals Methods of analysis of a reinforced concrete section under bending with axial force in the post-yield range

2014 ◽  
Vol 13 (3) ◽  
pp. 119-126
Author(s):  
Jacek Korentz
Keyword(s):  
Reinforced Concrete ◽  
Axial Force ◽  
Concrete Cover ◽  
Reinforcing Bars ◽  
Concrete Members ◽  
Extreme Loads ◽  
Concrete Confinement ◽  
The Moment ◽  
The Relationship ◽  
Concrete Section

Predicting the behaviour of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquakes plays an important role in assessing maximum stable deformation capacities of framed concrete structures. This paper presents the analytical procedure for analysing the behaviour of a reinforced concrete section under bending with axial force in the post-yield range. The following stages of section behaviour are defined: the uncracked, first cracked, yielding, cover crushing, cover spalling, buckling of bars and limit stages. The relationship between the moment and curvature in these stages, including the effects of concrete confinement, the spalling of the concrete cover, and the inelastic buckling of the reinforcing bars, is considered. The presented method makes it possible to estimate the ductility of reinforced concrete members with various longitudinal and transverse reinforcement.

scholarly journals FIRE RESISTANCE OF REINFORCED CONCRETE SLABS ACCORDING TO EC2 AND BRANZ TR8

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Sanin Džadić
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Construction Materials ◽  
Concrete Cover ◽  
Fire Engineering ◽  
Reinforced Concrete Slabs ◽  
Eurocode 2 ◽  
Floor Systems ◽  
Different Depths ◽  
Rc Slabs

Concrete elements are practically an integral part of every construction project andbuilding. They have significantly higher fire resistance in comparison to elements madeof other construction materials. However, RC slabs are the most sensitive concreteelements to the effects of fire when compared to all the other reinforced concrete elements.Therefore, this research focuses on determining the fire resistance of RC slabs usingMethod for determining fire resistance of slabs BAS EN 1992-1-2:2017, Eurocode 2,Design of concrete structures, Part 1-2: Structural fire design (Tabulated Data) andBRANZ Technical recommendation No. 8 – Method for Fire Engineering Design ofStructural Concrete Beams and Floor Systems. A fire action to RC slabs is modeled usingstandard fire ISO 834-1 (BAS EN 1991-1-2:2015). This research considers determiningfire resistance of simply supported RC slabs of different spans and different depths withvariations of concrete cover.

Sign in / Sign up

Export Citation Format

Share Document