Changes of bond strength properties of hot-dip galvanized plain bars with cement paste after 1 year of curing

Pokorný, Petr; Pernicová, Radka; Tej, Petr; Kolı́sko, Jiřı́

doi:10.1016/j.conbuildmat.2019.07.147

Cited by 14 publications

(39 citation statements)

References 39 publications

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“…The corrosion rate and free corrosion potential values are stated in Table 3. When the block is flooded, the active zinc (free corrosion potential falls in the range between −1000 and −1100 mV vs. SCE (Saturated Calomel Electrode)) corrosion rate is very high, while hydrogen is formed [6,11,22]. Upon reducing the relative humidity to 95%, the corrosion rate dropped; however, based on the values of free corrosion potentials, zinc was still active in terms of corrosion.…”

Section: Resultsmentioning

confidence: 99%

“…A protective layer on rebar created by conventional hot-dip galvanizing has several indisputable advantages—primarily, it provides high resistance for the coating, even in carbonated concrete, higher tolerance to chlorides, and also its affordable price [5]. Research [6] as well as practice [7] showed that significant corrosion damage (with hydrogen evolution—see Equation (1)) to the coating in fresh and curing concrete increases porosity at the interface with the cement paste [6,8,9], reducing bond strength between the rebar and concrete. 2H2normalO+2e−→H2+2OH−…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

2019

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This paper studies the effect of water as an oxidation agent and also of oxygen on zinc corrosion kinetics in active state in concrete, using high-sensitivity electrical resistance sensors. It was proven that zinc corrosion in active state is strongly affected by the presence of water at its surface. Zinc corrosion in real concrete in the absence of water can be misinterpreted as salt passivity. The presence of oxygen results in an increase of zinc corrosion rate, however at pH 12.6, passivity can occur. It was verified that corrosion products consisting primarily of Ca[Zn(OH)3]2·2H2O cannot effectively passivate zinc surface in concrete, even after 1800 h of exposure and zinc, or hot-dip galvanized steel can corrode at an unacceptable corrosion rate (more than 4 µm·a−1).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

2019

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“…Regarding the results of testing the bond strength between the prestressing reinforcement and UHPC (see Figure 10), the validity of the general equation T c,i (Equation (2)) for a conventional ribbed bar reinforcement can be confirmed in the area with already significant deceleration of the bond stress growth (~0.5 mm slip) [42]. The effect of relaxation due to increasing temperature on bond is not considered in this work.…”

Section: Bond Strengthmentioning

confidence: 89%

“…To simplify, the mechanical properties of concrete for bond strength tests can be characterized by compressive strength, both in the case of prestressing reinforcing bars [26] and conventional rib reinforcing bars [39,40]. Bond strength for concrete with an arbitrary steel profiled reinforcement (T c,i -bond force) can be characterized by the bond strength factor if (Equation 2 [41,42]). Bond strength factors (i f -Equation (2)) take into account the contributions of individual physical forces-i fad (factor of adhesion force), i ff (factor of friction force), i fσ (factor takes into account mechanical properties of concrete).…”

Section: Bond Strengthmentioning

confidence: 99%

Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

et al. 2020

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The study explores the effect of elevated temperatures on the bond strength between prestressing reinforcement and ultra-high performance concrete (UHPC). Laboratory investigations reveal that the changes in bond strength correspond well with the changes in compressive strength of UHPC and their correlation can be mathematically described. Exposition of specimens to temperatures up to 200 °C does not reduce bond strength as a negative effect of increasing temperature is outweighed by the positive effect of thermal increase on the reactivity of silica fume in UHPC mixture. Above 200 °C, bond strength significantly reduces; for instance, a decrease by about 70% is observed at 800 °C. The decreases in compressive and bond strengths for temperatures above 400 °C are related to the changes of phase composition of UHPC matrix (as revealed by X-ray powder diffraction) and the changes in microstructure including the increase of porosity (verified by mercury intrusion porosimetry and observation of confocal microscopy) and development cracks detected by scanning electron microscopy. Future research should investigate the effect of relaxation of prestressing reinforcement with increasing temperature on bond strength reduction by numerical modelling.

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“…However, introducing a galvanized concrete element to the reinforcement causes some disturbances at the metal-concrete interface. The standard explanation with reference to the mechanical aspects should also include electrochemical issues [ 6 , 7 , 8 ]. Three fundamental processes are generally involved in transmitting stress from the rebar to concrete.…”

Section: Introductionmentioning

confidence: 99%

An 18-Month Analysis of Bond Strength of Hot-Dip Galvanized Reinforcing Steel B500SP and S235JR+AR to Chloride Contaminated Concrete

2021

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This article describes the comparative analysis of tests on bond strength of hot-dip galvanized and black steel to concrete with and without chlorides. The bond effect was evaluated with six research methods: strength, electrochemical (measurements of potential, EIS and LPR), optical, and 3D scanning. The tests were conducted within a long period of 18 months on 48 test elements reinforced with smooth rebars ϕ8 mm from steel grade S235JR+AR and ribbed rebars ϕ8 mm and ϕ16 mm from steel grade B500SP. The main strength tests on the reinforcement bond to concrete were used to compare forces pulling out galvanized and black steel rebars from concrete. This comparative analysis was performed after 28, 180, and 540 days from the preparation of the elements. The electrochemical tests were performed to evaluate corrosion of steel rebars in concrete, particularly in chloride contaminated concrete. The behaviour of concrete elements while pulling out the rebar was observed using the system of digital cameras during the optical tests. As regards 3D scanning of ribbed rebars ϕ8 mm and ϕ16 mm, this method allowed the detailed identification of their complex geometry in terms of determining the polarization area to evaluate the corrosion rate of reinforcement in concrete. The test results indicated that the presence of zinc coating on rebars had an impact on the parameters of anchorage. In the case of ribbed rebars of 16 mm in diameter, the maximum values of adhesive stress and bond stiffness were reduced over time when compared to black steel rebars. Moreover, it was noticed that the stiffness of rebar anchorage in chloride contaminated concrete was considerably higher than in concrete without chlorides.

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Changes of bond strength properties of hot-dip galvanized plain bars with cement paste after 1 year of curing

Cited by 14 publications

References 39 publications

Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

An 18-Month Analysis of Bond Strength of Hot-Dip Galvanized Reinforcing Steel B500SP and S235JR+AR to Chloride Contaminated Concrete

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Changes of bond strength properties of hot-dip galvanized plain bars with cement paste after 1 year of curing

Cited by 14 publications

References 39 publications

Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

Kinetics of Zinc Corrosion in Concrete as a Function of Water and Oxygen Availability

Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

An 18-Month Analysis of Bond Strength of Hot-Dip Galvanized Reinforcing Steel B500SP and S235JR+AR to Chloride Contaminated Concrete

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Changes of bond strength properties of hot-dip galvanized plain bars with cement paste after 1 year of curing