• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.599-602
• /
• 2005

In this research, the characteristics of the strength development and chloride attack resistance on the concrete using high early strength cement by steam curing temperature condition were studied. As a result, It is observed that the early strength(16hr) is increasing and the strength of 28 days is decreasing, according as the rising of the steam curing temperature without the kinds of base cement(OPC and high early strength cement). On the other hand, it is observed that the more the contents of the unit binder(base cement + GGBF) is abundant, the more the steam curing temperature can be reduced in case of the high early strength. Also, the chloride attack resistance is improved according as the amount of GGBF is increased with the kinds of base cement(OPC and high early strength cement).

• Journal of the Korean institute of surface engineering
• /
• v.21 no.4
• /
• pp.168-175
• /
• 1988

The nickel0zinc allot depositions have been studjen in ammonium chloridw added chloride baths to fine out the effects of ultrasonic irradiation for the electrodeposition processes. The compositions of deposited alloys, the current efficiencies, corrosion resistance and brightness in various conditions of electrodeposition were investigated, in the range of ultrasonic irradiation of 50,500 and 1,000kc/s respectively. The results obtained are as follows; 1. the ratio of nikel to zinc in the deposit increased according 시 the ammonium chloride concentration in irradiated baths. 2. The current efficiencies became also higer in the irradiated bath. 3. Ammonium ions in solution seem to retard formation of zinc hydroxide. 4. The corrsion resistance and brightness of the deposits are dependent upon nickel content of deposits which ranges 10-18%(wt)nickel in the irradiated baths and 11-15%(wt)in ninirradisted baths. 5. The corrosion resistance and brightnes of the deposited are appreciably better in the irradiated baths than in non-irradiated bath with the mole ratio of 3.4(NH+4/Ni+++Zn++).

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.505-508
• /
• 2005

Concrete has a void, which exists as one of defect in concrete. If the porosity of concrete increases, durability of concrete decreases. In this paper, to improve surface void of concrete, surface penetration sealers are applied to specimen. And it were investigated that the resistances of chloride penetration and freezing and thawing for concrete with surface penetration sealer of two types. According to the results, surface penetration sealer has not show a harmful influence on strength and resistance of freezing and thawing. Also, B type surface penetration sealer was more superior in resistance of chloride penetration.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.315-316
• /
• 2023

In the present investigation, the chloride ion penetration resistance of nuclear power plant concrete with varying water-to-cement ratios was assessed. A comparative analysis was conducted on concretes that do not incorporate supplementary cementitious materials, such as fly ash, using permanently decommissioned nuclear structures as a reference. The objective is to employ this acquired data as a fundamental resource for the evaluation of the residual service life of nuclear power plant structures in subsequent studies.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.153-154
• /
• 2009

This study examined the field applicability of promoted high durability concrete (PHDC) developed for improving the chloride penetration resistance of coastal landfill underground structures. PHDC was found superior to conventional concrete containing slag in watertightness, crack resistance, and chloride penetration resistance required in coastal landfill underground structures. It was also more workable in field application, and easier to control the quality. This study investigated the strength development, crack resistance, and chloride penetration resistance of PHDC, and performed life evaluation of underground concrete structures of coastal landfill using the Life 365 program.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.483-486
• /
• 2005

This study investigates the effect of air contents on concrete properties, compressive strength, chloride migration coefficient and freeze-thaw resistance. Chloride migration and freeze-thawing test conducted in accordance with NT-BUILD 492 and pr-EN 12390-9, respectively. As a result, compressive strength reduced with air contents increase, but chloride migration coefficient more influenced by the water-binder ratios than air contents. Air contents of hardened concrete measured half times that of fresh concrete after mixing. Also, concrete scaling decreased with air contents increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.375-378
• /
• 2005

In this study, calcium chloride($CaCl_2$), sodium chloride (NaCl), organic acids-containing deicer(NS 40, NS 100), mixed deicier($NaCl\;70\%\;+\;CaCl_{2}\;30\%,\;NS\;40\;70\%\;+\;CaCl_{2}\;30\%,\;NaCl\;70\%\;+\;NS\;40\;30\%,\;NS\;40\;70\%\;+\;NaCl\;30\%$) is investigated based on the laboratory test for freez-thaw resistance of concrete and corrosion of metal. As a test results, in case of the use chloride-containing deicier in area that concrete structures has subjected to freez-thaw reaction in winter season, it showed desirable method that use deicing chemicals mixed with optimum ratio rather than use one deicing chemicals when is consider to deicing performance and effects, corrosion of steel materials, freez-thaw resistance of concrete. When use various deicing chemicals mixed, NS40($70\%$)+Calcium chloride($30\%$) showed the best effective method.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.10a
• /
• pp.52-53
• /
• 2016

Mechanical properties and durability of recycled aggregate concrete was known to decrease due to the adhesive mortar of recycled aggregate. But in this study, As the result of chloride diffusion resistance of recycled fine aggregate mortar, the mechanical properties are reduced according to the increase of the substitute ratio of recycled fine aggregate. But the chloride diffusion coefficient was almost same with natural fine aggregate mortar.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.6
• /
• pp.73-81
• /
• 2012

Concrete structures are commonly exposed to freezing-thawing condition. This freezing-thawing action changes the pore structure of concrete, and it can reduce the durability of concrete. In this study, the change of the internal pore structure and durability of concrete due to freezing-thawing action are investigated. According to results, the excellent durability records were reported by the existing evaluation methods for all mixes. However, the pores, 50~100nm size in diameter, are increased in concrete specimens exposed to freezing-thawing action, and the chloride penetration resistance was significantly reduced. The linear relationship between pore structure and chloride penetration resistance was shown in water cured concrete. Meanwhile, the linear relationship was decreased when concrete is exposed to freezing-thawing condition. It is desirable to review the criterion of durability evaluation for concrete specimens exposed to freezing-fthawing and chloride attack condition, simultaneously.

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