• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.3
• /
• pp.307-313
• /
• 2022

In this study, the correlation between Half Cell Potential(HCP) and the corrosion influencing factors was analyzed with considering three levels of water-cement ratio, the concentration of chloride solution, and cover depth. As a result of long-term corrosion monitoring, HCP behavior was close to the critical corrosion potential(-350 mV) in all water-cement ratios in the case of 3.5 % and 7.0 % chloride concentration. Regarding the passed charge test in 548 curing days, the passed charge results were improved to 'Moderate' grade. Multiple regression analysis was performed to evaluate the correlation between corrosion influencing factors and HCP, and it was evaluated that the effects of influencing factors to HCP were in the order of chloride concentration, water-cement ratio, and cover depth. In the case of the relationship between HCP and the passed charge, the coefficient of determination showed a high level of 0.9, which yielded a close correlation between the passed charge and HCP.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.124-132
• /
• 2022

The corrosion potential in concrete varies greatly with exposure and concrete mix conditions. In this study, RC (Reinforcement Concrete) samples were prepared considering cover depth, chloride concentration, and W/C(water to cement) ratio as variables, and HCP(Half Cell Potential) was measured, which evaluated comparative potential between embedded steel and concrete surface. In addition, OCP(Open Circuit Potential) was measured using buried steel and CE(Counter Electrode). Agar and NaOH solution were used as ion exchange materials and Hg/HgO was used for RE(Reference Electrode), which was more sensitive to temperature than HCP. Among the influencing factors, the exposure period and chloride concentration had a relatively greater effect than cover depth and w/c ratio. Additionally, the entire measured HCP and OCP showed a clearly linear relationship with increasing cover depth and w/c ratio. Through multiple regression analysis, the relationship between HCP and OCP was quantified, and an improved correlation was obtained with temperature effect.

• Journal of the Korea Concrete Institute
• /
• v.25 no.6
• /
• pp.621-630
• /
• 2013

Several techniques for steel corrosion detection are proposed and HCP (half cell potential) technique is widely adopted for field investigation. If concrete has cracks on surface, steel corrosion is rapidly accelerated due to additional intrusion of chloride and carbon dioxide ions. This study is for an evaluation of HCP in cracked concrete exposed chloride attack. For this work, RC (reinforced concrete) beams are prepared considering 3 w/c ratios (0.35, 0.55, and 0.70) and several cover depths (10~60 mm) and various crack widths of 0.0~1.0 mm are induced. For 35 days, SST (salt spraying test) is performed for corrosion acceleration, and HCP and corrosion length of rebar are evaluated. With increasing crack width, w/c ratios, and decreasing cover depth, HCP measurements increase. HCP evaluation technique is proposed considering the effects of w/c ratios, crack width, and cover depth. Furthermore anti-corrosive cover depths are obtained through Life365 program and the results are compared with those from this study. The results shows relatively big difference in cracked concrete, however provide similar anti-corrosive conditions in sound concrete.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.1-13
• /
• 2022

This study aims to investigate the feasibility of the half-cell potential (HCP) measurements on the concrete surface for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete. A series of experimental study is performed to measure HCP (or corrosion potential, E_corr) and corrosion current density (i_corr) of reinforcing steel in concrete cube specimens, with a side length of 200 mm. Various corrosion levels in a range of 0% to 20% of the test specimens are accelerated by impressing current to the reinforcing steel in concrete immersed in 3.0 % NaCl solution. HCP is measured in accordance with ASTM C876-15, and corrosion current density is determined by using the Stern-Geary equation and measured polarization resistance measured by electrochemical impedance spectroscopy (EIS). As a result, a numerical formula that relates HCP and i_corr in the test specimen is established by a regression analysis of the measured data in this study. It is observed that HCP is linearly correlated with log(i_corr) with a R² greater than 0.87, which is less affected by the experimental variables such as concrete mixture proportion, diameter of reinforcing steel and the amount of applied current in this study. These results exhibit that HCP measurements could be effective for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete in the case of exposed to a certain consistent environment.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.2
• /
• pp.113-120
• /
• 2017

HCP(Half Cell Potential) method has been widely used since it is recognized as a efficient NDT(Non Destructive Technique) for corrosion detection. This work is for an evaluation of relation between corrosion amount and measured HCP in dried condition through ICM(Impressed Current Method) for accelerating corrosion. For the work, cement mortar specimens with three w/c ratios and four cover depths are prepared, and corrosion test based on ICM is performed for 6 hours, 18 hour, and 42 hours with constant 20V of electrical charge, respectively. From the test, corrosion amount increases with reduced cover depth, increasing w/c ratio, and extended corrosion period, where corrosion amount is evaluated to linearly increases with measured HCP in dried condition. In order to evaluate corrosion amount through measured HCP, the measured HCP level is firstly determined and then corrosion amount is to be compared with measured HCP, which is evaluated to be more reasonable with higher C.O.V.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.3
• /
• pp.19-26
• /
• 2017

Concrete is a construction material with porous media and corroded steel inside affects negatively to durability and structural safety. This study aims a derivation of quantitative relationship between measured HCP (Half Cell Potential) and corrosion amount considering cover depth and W/C (water to cement) ratio. For the work, cement mortar specimens with 3 different W/C ratios and 4 different cover depths are prepared, HCPs are measured with 3 different corrosion level. HCP measurement significantly increases in the saturated condition and linear relationship is observed between corrosion level and acceleration period. With increasing corrosion level and W/C ratio, and decreasing cover depth, HCP measurement increases. Considering total corrosion level and HCP measurements, relatively low COV(Coefficient of Variation) of 0.67 is evaluated through multi-linear regression analysis, however higher COVs over 0.90 can be obtained considering level of HCP measurement. In the room condition, corrosion level can be evaluated through measured HCP in the given conditions of cover depth, W/C ratio. diameter of steel inside.

• Journal of Conservation Science
• /
• v.34 no.6
• /
• pp.503-515
• /
• 2018

Stupa of State Preceptor Jigwang at Beopcheonsa temple site, Wonju, was conserved and restored in 1957. It was necessary to assess the degree of damage to the used mortar and to provide objective data on the necessity of its removal. Therefore, the HCP(half-cell potential) measurement used in concrete fields was applied. Multi-regression analysis of HCP data, following the rapid corrosion test of the roofstone mortar used by the rebar, resulted in a high correlation of HCP values(0.86), depending on the amount of corrosion and cover depth used for the steel bar. As a result, high correlation values(0.86) for the coefficients of determination were derived. The showed that the measurement of the wet conditions -431 to -663 mV on the roofstone indicated a corrosion damage rate of 90% or more after removal and restoration.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.2
• /
• pp.191-199
• /
• 2021

In this study, the correlation between the influencing factors on corrosion and Half Cell Potential(HCP) measurement was analyzed considering the three levels of W/C ratio, cover depth, and chloride concentration. The HCP increased with enlarged cover depth, so it was confirmed that the increment of cover depth was effective for control of corrosion. Based on the criteria, the case of 60mm cover depth showed excellent corrosion control with under -200mV, indicating increase of cover depth is an effective method for reducing intrusion of external deterioration factors. When fresh water was injected to the upper part of specimens, very low level of HCP was monitored, but in the case that concentrations of chloride were 3.5% and 7.0%, HCP dropped under -200mV. In addition, the case with high volume of unit binder showed lower HCP measurement like increasing cover depth. Multiple regression analysis was performed to evaluate the correlation between the corrosive influence factors and HCP results, showing high coefficient of determination of 0.97. However, there were limitations such as limited number of samples and measuring period. Through the additional corrosion monitoring and chloride content evaluation after dismantling the specimen, more reasonable prediction can be achieved for correlation analysis with relevant data.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.6
• /
• pp.95-103
• /
• 2013

Half Cell Potential (HPC) technique has been widely adopted for its quantitative evaluation of corrosion possibility. In this study, RC specimens with three different cover depths (10mm, 30mm, and 60mm) and w/c ratios (0.35, 0.55, and 0.70) are prepared and accelerated salt spray test (SST) is performed for 45 days. Steel corrosion occurs in the specimens with 0.55 of w/c and 10mm of cover depth. In the case of 0.70 of w/c and 30mm of cover depth, steel corrosion is also monitored. Considering the effect of cover depth and w/c ratio, HCP evaluation equation is proposed and the condition which can control steel corrosion is obtained. Furthermore, anti-corrosive conditions containing w/c ratio and cover depth are analyzed through Life 365 program and the conditions are compared with the results from this study.