Problems Connected with use of Hot-dip Galvanized Reinforcement in Concrete Elements

Pernicová, Radka; Dobiáš, Daniel; Pokorný, Petr

doi:10.1016/j.proeng.2017.02.086

Cited by 23 publications

(10 citation statements)

References 10 publications

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“…Found that effect added to increase the thickness of the galvanize layer appeared at periods of time (240-600 sec) and the effect was increased by (5.5% Al). The increase in dipping time gave a good chance for the growth of the interlayer whether adjacent to the surface of the steel, usually with the aluminum ternary alloy (Al-Fe-Zn) , and the developing layer of molten freeze made up of zinc and added aluminum and other elements (lead and residual metal residues from zinc purification), which may also be a ternary alloy of (Al-Zn-Pb), and the more time dipping in the molten increased the tem-perature of the sample reaches up to a degree close to the molten and thus helped to grow and be a thick layer free of defects [14] (12-11-10) shows the relationship between the bending angle and the bending curve produced for (4.5%, 5%, 5.5% Al) and for different time periods of the galvanized. Observed as in figure (10) no effect on the thickness of galvanize layer at period times (15-60 sec.…”

Section: Resultsmentioning

confidence: 99%

“…Samples with (Al-5.5% addition) showed the cracking behavior and the nature of the breakage in the galvanize layer with increasing dipping time in the molten as observed in Figs. (13,14,15,16,17,18) the cracks are formed in the adhesion layer of steel and grow towards the interstellar layer until it reaches the surface layer and whenever the interstellar layer thicker increase the longitudinal cracks in the adhesion and leading to the separation of galvanize layer as showed in Figures (13,14,15), the increase in longitudinal and transverse cracks in the interstellar layer and its growth towards the surface layer leads to a breakage in the total galvanize layer and the breakage of the galvanize layer at the bending angle (30°) were appeared due to the shear stress between the cracks in the thick interstitial layer due to bending [16], as shown in figures (16,17,18 Figure (19) shows the relationship between the hardness (HV) and the time of exposure to erosion of the galvanize samples with addition ratios (4.5%, 5%, 5.5% Al). observed that the change few in the hardness of the samples at the time of exposure to the limit of (10000 s) in the presence of Thickness galvanize layer at the beginning of time When more than (10000 s) is passed, the value of hardness is increased due to the removal of the layers of galvanize to reach the highest hardness value, which represents the hardness of the steel.…”

Section: Resultsmentioning

confidence: 99%

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Effect of Aluminum Powder additive on Erosion and Bending Resistance of Galvanize Layer

Othman¹,

2018

IJET

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Study of the effect of adding aluminum powder to galvanize melt on the microstructure, thickness of the galvanize layer, behavior and nature of fracture in the total layer through the use of optical microscope and scanning electron microscopy. The addition of the aluminum component (4.5%, 5%, 5.5%) to molten is increase the total thickness of the galvanize layer because it increases the thickness of the interlayer and the adhesive layer with the low carbon steel coupled with the increased dipping time in the molten which also increases the thickness of the total galvanize layer. The cracks that were obtained from the bending test were examined for the samples. The samples with the large thickness and the addition ratio (Al-5.5%) were more resistant to bending. The cracks did not penetrate the surface of the galvanize layer until the angle of bending with the horizon (30º). The erosion resistance was compared to the exposure time of the selection samples, and showed good resistance to erosion at average exposure time. These samples are good in the manufacture of high and medium voltage transmission towers.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effect of Aluminum Powder additive on Erosion and Bending Resistance of Galvanize Layer

Othman¹,

2018

IJET

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“…Hamid & Mike [ 48 ] refer to contradictory results in the literature, but conclude galvanisation has no significant impact on bonding in NSC. A dissenting opinion is voiced by Pernicova et al [ 49 ] who found that the formation of hydrogen during the passivation reaction causes porosity in the surrounding cement thereby deteriorating the bond strength. The severity of this effect was found to be dependent on the pH value of the concrete.…”

Section: Cable Reinforcementmentioning

confidence: 99%

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

et al. 2017

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The Material Deposition Method (MDM) is enjoying increasing attention as an additive method to create concrete mortar structures characterised by a high degree of form-freedom, a lack of geometrical repetition, and automated construction. Several small-scale structures have been realised around the world, or are under preparation. However, the nature of this construction method is unsuitable for conventional reinforcement methods to achieve ductile failure behaviour. Sometimes, this is solved by combining printing with conventional casting and reinforcing techniques. This study, however, explores an alternative strategy, namely to directly entrain a metal cable in the concrete filament during printing to serve as reinforcement. A device is introduced to apply the reinforcement. Several options for online reinforcement media are compared for printability. Considerations specific to the manufacturing process are discussed. Subsequently, pull-out tests on cast and printed specimens provide an initial characterisation of bond behaviour. Bending tests furthermore show the potential of this reinforcement method. The bond stress of cables in printed concrete was comparable to values reported for smooth rebar but lower than that of the same cables in cast concrete. The scatter in experimental results was high. When sufficient bond length is available, ductile failure behaviour for tension parallel to the filament direction can be achieved, even though cable slip occurs. Further improvements to the process should pave the way to achieve better post-crack resistance, as the concept in itself is feasible.

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“…The disadvantage of zinc coating is its possible corrosion after the contact with highly alkaline pore solution at pH < 11.4 and pH ≥ 13.3 [37,38]. This unfavorable occurrence is usually observed in the initial phase of bonding fresh concrete mix in the formwork, in which galvanized reinforcement is laid [39]. In this context it is crucial that there is only one-side limit of pH values for black reinforcing steel-pH < 11.8, below which corrosion develops.…”

Section: Introductionmentioning

confidence: 99%

A Two-Year Evaluation of Corrosion-Induced Damage to Hot Galvanized Reinforcing Steel B500SP in Chloride Contaminated Concrete

et al. 2020

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Corrosion-induced damage to concrete reinforced with bars is a serious problem regarding technical and economic aspects and strongly depends on used materials, corrosion environment, and service life. Tests described in this paper refer to a two-year evaluation of the effectiveness of protection provided by zinc-coated low-carbon reinforcing steel of grade B500SP in concrete against chloride corrosion. Performed tests were comparative and included measurements conducted on four groups of concrete test elements with dimensions of 40 mm × 40 mm × 140 mm reinforced with a bar having a diameter of ϕ8 mm. Particular groups were a combination of different types of concrete with or without chloride additives, with galvanized or black steel. Chlorides as CaCl2 were added to the concrete mix in the amount of 3% of cement weight in concrete. Reinforced concrete specimens were periodically monitored within two years using the following techniques: linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Polarization measurements were conducted in a three-electrode arrangement, in which a rebar in concrete served as a working electrode, stainless steel sheet was used as an auxiliary electrode, and Cl−/AgCl,Ag was a reference electrode. Comparative tests of changes in the density of corrosion current in concrete specimens without chloride additives basically demonstrated no development of corrosion, and possible passivation was expected in case of black steel. Higher densities of corrosion current were observed for galvanized steel during first days of testing. The reason was the dissolution of zinc after the contact with initially high pH of concrete pore solution. Six-month measurements demonstrated a higher density of corrosion current in concrete specimens with high concentration of chlorides, which unambiguously indicated corrosion in concrete reinforced with galvanized or black steel. Densities of corrosion current determined for selected specimens dramatically decreased after an 18-month interval in measurements. Corrosion was even inhibited on black steel as an insulating barrier of corrosion products was formed. The above observations were confirmed with structural studies using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. Results obtained from corrosion (LPR, EIS) and structural (SEM, EDS) tests on specimens of concrete reinforced with steel B500SP demonstrated a very favorable impact of zinc coating on steel by providing two-year protection against corrosion in the environment with very high chloride content.

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Problems Connected with use of Hot-dip Galvanized Reinforcement in Concrete Elements

Cited by 23 publications

References 10 publications

Effect of Aluminum Powder additive on Erosion and Bending Resistance of Galvanize Layer

Effect of Aluminum Powder additive on Erosion and Bending Resistance of Galvanize Layer

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

A Two-Year Evaluation of Corrosion-Induced Damage to Hot Galvanized Reinforcing Steel B500SP in Chloride Contaminated Concrete

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