Papers by Keyword: Reinforcing Steel

Abstract: A technique for applying a protective and hardening coating on steel 18G2S by electrodeposition from ionic melts has been developed. Melt in the triple eutectic point of salts NaF - 30%, NaCl - 16.6% and AlF3 - 53.4% is used as an electrolyte. During electrolysis, a graphite crucible was used as an anode, samples of reinforcing steel (18G2S) cleaned of corrosion and other contaminants were used as a cathode. The temperature of the ionic melt during electrolysis was 1120 ± 5K. In the process of electrolysis, the value of the electric current and voltage were controlled, the change in the mass of the deposited aluminium over a given time was measured. The current output during the deposition of aluminium was kept in the range of 89 ... 96 %. During electrolysis, aluminium diffuses into the surface layers of steel and with iron form solid solutions, intermetallic compounds and eutectics. At the same time, crystals of the FeAl₃ compound (59.18% Al) appear in the structure. A further aluminium content decrease in the depth of the surface layer entails the appearance of chemical compounds of the following compositions: Fe₂Al₇, Fe₂Al₅, FeAl₂ , FeAl. The elasticity limit and ultimate tensile strength of aluminium-coated samples compared to uncoated samples increased by 7.9% and 7.8% respectively. Electrochemical oxidation of samples with aluminium coating of reinforcing steel in sulfuric acid electrolyte was carried out. The oxidation rates for aluminium are set within (7.1... 8.3) 10^-6 g / (s mm2) and iron (7.6 10.4) 10^-6 g / (s mm2). Experimental assessment of samples oxidation rate under conditions of sulfuric acid electrolyte was carried out at an electric current value of 11 to 18 A.

Abstract: Moisture contents of concrete can affect the corrosion of reinforcing steel. In this paper, moisture contents of concrete were increased by filling the small holes with water or fully submerging in water. The effect of moisture contents on the corrosion behaviors of cathodic and anodic steel was investigated by comparing the half-cell potential, micro-cell and macro-cell current density. The results indicated that when only the concrete around cathodic steel was in water-saturated state, it could greatly weakened the kinetics of cathodic reaction and resulted in a considerable decrease in macro-cell current. When only the concrete around anodic steel was in water-saturated state, it could not effectively inhibit the macro-cell corrosion. When both the concrete around the cathodic steel and the anodic steel were in water-saturated state, the macro-cell current flowing between cathode and anode could be inhibited effectively, and the corrosion was little affected by chloride contents.

Abstract: The performance of reinforced concrete structures under combined effects of blast and fire is growing in interest of the research and engineering communities specially after the recent terrorist attacks as well as severe accidents (i.e. Gotthard tunnel, etc.). The mechanical behaviour of concrete and reinforcing steel when are subjected to extreme temperatures, impacts or blast has still many aspects open to investigation. In this paper the behaviour of AISI304, B500B and B500A reinforcing steel at high strain rate (500 s^-1) and at three levels of temperature (200, 400 and 600°C) is presented. The results were obtained by using a Split Hopkinson Tensile Bar (SHTB) equipped with a heating system.

Abstract: 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.

Abstract: This paper presents the results of experimental research on the influence of using microcrystalline phosphating process on the OB37 steel used in construction. For this purpose, the samples were immersed in phosphate solution and the structures were characterized using SEM microscope. The results show that the obtained structures, are influenced by pH and immersion time and show a good surface compactity and roughness, which means that the obtained layer on the OB37 reinforcement improves corrosion resistance and adhesion of these reinforcements in the reinforced concrete.

Abstract: This paper presents the first results of complex study concerning the protection of reinforcing steel used in concrete structures from civil and industrial buildings. The obtained coatings have multiple purpose, increasing the corrosion resistance but also the adherence with the concrete, improving the overall performance of concrete and its durability.

Abstract: In this paper, the performance of two kinds of migrating corrosion inhibitors on the corrosion behavior of steel in concrete under wet-dry cycle was investigated. The wet-dry cycle duration on the open circuit, current density and impedance of carbon steel imbedded in concrete were analyzed by linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). The results show that two kinds of migrating corrosion inhibitors can restrain corrosion of reinforcing steel, the corrosion efficiency of ZX was less more than MCI. Migrating corrosion inhibitor not only can improve carbon steel impedance, also can improve concrete resistant. Key words: migrating corrosion inhibitor;Cl^-;reinforcing steel;linear polarization resistance;electrochemical impedance spectroscopy

Abstract: In this article a preparation of computer model of reinforcing steel rolling process using program complexes “KOMPAS” and “DEFORM-3D” is described. In result was made a model that is fully corresponded the requirements of standards by geometric sizes. This model can be used for optimization of workshop rolling parameters of the reinforcing steel.

Abstract: The effect of steel surface conditions on the macro-cell polarization behavior of reinforcing steels embedded in cement mortar was investigated by comparing and analyzing the macro-cell current density and macro-cell polarization ratio of steels. The results indicated that steel surface conditions played an important role in controlling the macro-cell corrosion and polarization. The polished or pre-rusted surface had a better corrosion resistance to inhibit the flow of macro-cell current than the scaled surface that formed in the production process. Compared to the polished surface, the presence of mill scale or rust oxides on the surface of anodic steel could reduce the macro-cell polarization ratio of anode.

Abstract: Self-healing materials offer tremendous potential for providing long-lived structural materials. In this study, isophorone diisocyanate (IPDI) microcapsules as self-healing materials were synthesized via in situ polymerization. Thermogravimetric analysis characterized the thermal ability of IPDI, microcapsules and microcapsule shells. The morphology of microcapsules and microcapsule shells were characterized by FE-SEM. Scanning micro-reference electrode technique demonstrated that epoxy resin coatings with IPDI microcapsules on the surface of reinforcing steel Q235 could cure the scratched crevice by immersion in 0.01 M NaCl solution after the coating was scratched. The self-healing epoxy resin coating could protect Q235 from corrosion.