• Corrosion Science and Technology
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• v.15 no.1
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• pp.28-37
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• 2016

Due to the increased construction of offshore concrete structures and the use of de-icing salts for the purpose of snow removal, the needs for the development of anti-corrosive concrete are increasing. To solve these problems, an evaluation of the mechanical and durability properties for concrete were conducted by mixing modified-sulfur as 0 %, 5 %, 10 %, 15 % cement weight ratio. Both strengths and the properties affecting durability such as water absorption coefficient, chloride ion permeability, accelerated carbonation resistance, rapid freezing and thawing, and chemical resistance were evaluated. All evaluations performed were according to the test specifications associated KS. The results indicate that mixing of modified-sulfur lowed chloride ion permeability and improved chemical resistance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.217-223
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• 2005

This study is on the evaluation of three kinds of surface protectors for protecting reinforced concrete against corrosion of reinforcing steel by chloride attack and carbonation. In this study, the test has been carried out on the performance of specimens applied with surface protectors for anti-corrosion and anti-carbonation. The result showed that specimens applied with the three kinds of surface protectors, were excellent in resistance to the corrosion of reinforcing steel and carbonation. Especially the specimen applied with finish coating in conjunction with hydrophobic primer showed great reduction in the corrosion of reinforcing steel and carbonation.

• Resources Recycling
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• v.12 no.1
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• pp.41-47
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• 2003

In order to improve the hydration resistance of lime in the air at room temperature, carbonation and hydration experiments have been conducted. Carbonation of the surface of lime by about 6 wt％ was needed to suppress the hydration of lime used in steel-making. The effect of recirculation of rotary kiln exhaust gas for the carbonation of lime on the combustion temperature and NOx concentration was analyzed by thermodynamics. From the thermodynamic calculation results, it was frond that the equi-librium combustion temperature and NOx concentration decreased with increasing volume percentage of exhaust gas.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.265-271
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• 2014

It is strongly needed to investigate the fine sand as an alternative fine aggregate of well-graded river sand because the fine sand which is being enormously distributed in the midstream and downstream of Nakdong-River in Korea has a poor grading but good quality as a fine aggregate for concrete. Thus, the purpose of this experimental research is to evaluate the durability of concrete using the fine sand to utilize it actively as a fine aggregate. For this purpose, the concrete specimens using different fine sand were made for the specified concrete strength of 35MPa, and then their durability such as the resistance to freezing and thawing and carbonation, and drying shrinkage were evaluated. It was observed from the test results that the resistance to freezing and thawing and carbonation of concrete using the fine sand was similar to that of concrete using reference sand, but the drying shrinkage of concrete using the fine sand with small fineness was comparatively lager than that of concrete using reference sand.

• Advances in concrete construction
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• v.8 no.2
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• pp.119-126
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• 2019

This paper reports an experimental investigation conducted to evaluate the durability performance of concrete mixtures prepared utilizing blends of Type I Portland cement (OPC) and natural pozzolans (NPs) obtained from three different sources in Saudi Arabia. The control concrete mixture containing OPC alone as the binder and three concrete mixtures incorporating NPs were prepared keeping water/binder ratio of 0.4 (by weight), binder content of $370kg/m^3$, and fine/total aggregate ratio of 0.38 (by weight) invariant. The compressive strength and durability properties that included depth of water penetration, depth of carbonation, chloride diffusion coefficient, and resistance to reinforcement corrosion and sulfate attack were determined. Results of this study indicate that at all ages, the compressive strength of NP-admixed concrete mixtures was slightly less than that of the concrete containing OPC alone. However, the concrete mixtures containing NP exhibited lower depth of water penetration and chloride diffusion coefficient and more resistance to reinforcement corrosion and sulfate attack as compared to OPC. NP-admixed concrete showed relatively more depth of carbonation than OPC when subjected to accelerated carbonation. The results of this investigation indicates the viability of utilizing of Saudi natural pozzolans for improving the durability characteristics of concrete subjected to chloride and sulfate exposures.

• Corrosion Science and Technology
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• v.22 no.4
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• pp.273-286
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• 2023

Rebar is embedded in concrete to create reinforced concrete (RC). Rebar carries most of the tensile stress and gives compressively loaded concrete fracture resistance. However, embedded steel corrosion is a significant cause of concern for RC composite structures worldwide. It is one of the biggest threats to concrete structures' longevity. Due to environmental factors, concrete decays and reinforced concrete buildings fail. The type and surface arrangement of the rebar, the cement used in the mortar, the dosing frequency of the concrete, its penetrability, gaps and cracks, humidity, and, most importantly, pollutants and aggressive species all affect rebar corrosion. Either carbonation or chlorides typically cause steel corrosion in concrete. Carbonation occurs when carbon dioxide in the atmosphere combines with calcium within the concrete. This indicates that the pH of the medium is falling, and the steel rebar is corroding. When chlorides pass through concrete to steel, corrosion rates skyrocket. Consideration must be given to concrete moisture. Owing to its excellent resistance, dry concrete has a low steel corrosion rate, whereas extremely wet concrete has a low rate owing to delayed O₂ transfer to steel surfaces. This paper examines rebar corrosion causes and mechanisms and describes corrosion evaluation and mitigation methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.115-122
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• 2006

Ten types of steel bars having different Cr contents were embedded in concretes with chloride ion contents of 0.3, 0.6, 1.2, and $2.4kg/m^3$ to fabricate specimens assuming such deteriorative environments. After being carbonated to the reinforcement level, these concretes were subjected to corrosion-accelerating cycles of heating/cooling and drying/wetting. The time-related changes in the corrosion area and corrosion loss of the Cr-bearing rebars were then measured to investigate their corrosion resistance. The results revealed that in a deteriorative environment prone to both carbonation and chloride attack, corrosion resistance was evident with a Cr content of 7% or more and 9% or more in concretes with chloride ion contents of 1.2 and $2.4kg/m^3$, respectively.

• Journal of the Korea Institute of Building Construction
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• v.3 no.4
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• pp.103-109
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structural constructed with aggregated(dredged front sea). can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the corrosion reflectance of coated steel using polymer dispersion and polymer cement slurry. Polymer dispersion and polymer cement slurry with various polymer types were coated to the surface of bars and steel plate, and tested for accelerated corrosion tests. Tests include adhesion in tension, bending test, chloride ion spray, penetration of NaCl 10％ solution and carbonation. From the test results, the corrosive resistance of steel is considerably improved by using polymer dispersion and polymer cement flurry at surface of steel. The difference of the corrosive resistance is hardly recognized according to types of polymer dispersion. The coated steel using polymer dispersion and polymer foment slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.204-210
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• 2022

Cement is pointed out as the main cause of carbon dioxide emission in the construction industry. Many researchs are underway to use blast furnace slag, an industrial by-product, as a substitute for cement to reduce carbon dioxide emitted during the manufacturing the cement. When blast furnace slag is used as a substitute for cement, it has advantages such as long-term strength and chemical resistance improvement. However, blast furnace slag has a problem that makes initial strength low. This is due to the impermeable film on the surface created during the production of blast furnace slag. The created film is known to be destroyed in an alkaline environment, and based on this, previous studies have suggested a solution using various alkali activators. But, alkali activator is dangerous product since it is a strong alkaline material. And it has the disadvantage in price competitiveness. In this study, an experiment was conducted to improve the initial hydration reactivity of the blast furnace slag to secure the initial strength of the mortar substituted with the blast furnace slag and to check whether the carbonation resistance was increased. As a result of the experiment, it was confirmed that the mortar using alkaline water showed higher strength than the mortar using tap water, and there were more hydration products generated inside. In addition, it was confirmed that the mortar using alkaline water as a compounding water had high carbonation resistance.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.641-649
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• 2015

The purpose of this study was to assess the durability of high-strength concrete with high volume mineral admixture (HVMAC) derived from previous studies within ternary blended concrete (TBC) and normal concrete (NC). Four durability evaluation types such as chloride penetration resistance, freezing and thawing resistance, carbonation resistance in two pre-treatment conditions, and sulfuric acid and sulfate resistance using 5% sulfuric acid ($H_2SO_4$), 10% sodium sulfate ($Na_2SO_4$), and 10% magnesium sulfate ($MgSO_4$) solution were selected and performed in this study. HVMAC showed the excellent chloride penetration resistance in any age and the freezing and thawing durability close to 100%. In addition, HVMAC affected more reduction in carbonation resistance than TBC. When the curing time was increased, to create a concrete internal organization densely improved resistance to carbonation. HVMAC also showed the most superior in sulfuric acid and sulfate resistance. As the reduction of calcium hydroxide and $C_3A$ to apply a large amount of admixture reduced the swelling and cracking of concrete, the strength reduction and mass change of concrete was found to be small indicated.