• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.102-113
• /
• 2021

The deterioration environments caused by de-icing salt and airborne chlorides in the seashore, evaluated in the "Detailed guideline for safety and management practice of facilities (performance evaluation)", were reviewed in terms of penetrated chlorides into concrete on various road facilities. Target concrete structures, in this study, were 4 concrete barriers in Gangwon area, 3 concrete barriers and 1 retaining wall in Busan area, and 4 bridges in Gangwon-do, Seoul, Gyeonggi-do, and Busan. The deterioration environments were classified into three categories: direct and indirect de-icing salt attack, and airborne salt attack depending on the distance to seashore and the height of pier, and the penetrated chlorides in to concrete were analyzed. The results showed that (1) the regional deterioration environments were clearly classified by de-icing salt sprayed days (snowfall days), (2) the penetrated chlorides increased significantly when leakage occurred through slabs or expansion joints, and (3) the airborne chlorides affected to a height of 20 m concrete in the seashore, Busan. From these, it could be confirmed that the chloride ion penetration properties depend on the exposed aging environment, member location and height, and deterioration status, even on the same structure, so the selection of target members and location is very important in the inspection and maintenance. If the database of penetrated chlorides properties in various deterioration environments is constructed, it is expected that the proactive durability management on concrete structures will be possible in the field.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.2
• /
• pp.1-9
• /
• 2019

GGBFS(Ground Granulated Blast Furnace Slag), one of the representative concrete mineral admixtures, improves the long-term durability and engineering performance of concrete by latent hydraulic activity. In this study, considering 3 levels of W/B(0.37, 0.42, 0.47) and GGBFS replacement ratio(0 %, 30 %, 50 %), durability performances for chloride attack are evaluated, and equations which predict behavior of accelerated chloride diffusion are proposed. Also, the relationship between accelerated chloride diffusion coefficient and passed charge is evaluated. In target curing day, accelerated chloride diffusion tests(Tang's method, ASTM C 1202) and compressive strength(KS F 2405) are performed. In the 730 day's results of accelerated chloride diffusion coefficient, GGBFS concrete has up to 28 % of decreasing ratio compared to OPC concrete, and in those of passed charge, GGBFS concrete has up to 29 % of decreasing ratio compared to OPC concrete. Also, it is deemed that the impact of variation of W/B is less in GGBFS concrete than in OPC concrete. The equations which predict accelerated chloride diffusion coefficient and passed charge are drawn, based on the characteristics of mixture and test results. The equation which predicts passed charge shows slightly higher coefficient of determination than that which predicts accelerated chloride diffusion coefficient.

• Journal of Mushroom
• /
• v.19 no.4
• /
• pp.310-315
• /
• 2021

We investigated the effect of sodium chloride-associated abiotic stress on the development of Pleurotus ostreatus. We examined the growth characteristics of fruiting bodies, constituent amino acids, and fragrance pattern to determine the effect of culturing Pleurotus ostreatus on a sawdust substrate supplemented with sodium chloride in a dose-dependent manner. Pleurotus ostreatus fruiting bodies exhibited an increasing tendency towards augmented yields when grown in the presence of 0.5% sodium chloride as compared with that grown in the control group. However, increasing the supplementation of sodium chloride from 1.0 % to 2.0% resulted in significantly decreased yields of Pleurotus ostreatus fruiting bodies in these groups as compared with that in control groups. Further assessment revealed the presence of 14 types of amino acids in the fruiting bodies, including aspartate, threonine, serine, glycine, alanine, methionine, valine, isoleucine, leucine, phenylalanine, tyrosine, lysine, histidine, and arginine, at lower levels in all the sodium chloride-treated groups than in the control group; except for glutamic acid and proline. Similarly, fragrance pattern analysis of the Pleurotus ostreatus fruiting body by chromatography confirmed that the intensity of the substances presumed to be octane compounds, to which the unique flavor of mushrooms is attributed, was lower in all the sodium chloride-treated groups than in the control group.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.48 no.4
• /
• pp.397-404
• /
• 2021

The purpose of this study was to evaluate the effect of a hemostatic agent containing aluminum chloride on the shear bond strength of resin-modified glass ionomer cement (RMGIC) to the dentin of primary teeth. Thirty-six extracted non-carious human primary teeth were collected in this study. Dentin surfaces were cut and polished. The specimens were randomly divided into 4 groups; group I: RMGIC without conditioning; group II: polyacrylic acid (PAA), RMGIC; group III: aluminum chloride, RMGIC; group IV: aluminum chloride, PAA, RMGIC. All teeth were thermocycled between 5.0℃ and 55.0℃ for 5000 cycles. Fifteen specimens from each group were subjected to shear bond strength test and 3 specimens from each group were inspected using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. The mean shear bond strength of each group was as follows: 4.04 ± 0.88 MPa in group I, 8.29 ± 1.40 MPa in group II, 1.39 ± 0.47 MPa in group III, 6.24 ± 2.76 MPa in group IV. There were significant differences among all groups (p < 0.001). SEM image of the dentinal tubules were partially exposed in group III and group IV. Fully exposed dentinal tubules were found in group II. In conclusion, aluminum chloride decreased the shear bond strength of RMGIC to dentin, regardless of PAA conditioning.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.553-557
• /
• 2022

The present study evaluate the chloride extracion under electrochemical chloride extraction method. Chloride was penetrated into the concrete from external reservoir using a 4M NaCl solution, and an electrochemical chloride extraction method was applied after the curing period of 1 year. The current density was constantly kept 1000 mA/m² for coulostatic application with the variation in potential difference. The duration of the ECE treatment was 2, 4, 8 weeks, respectively. The residual chloride concentration at all depths decreased, and the chloride concentration decreased as the application period increased. After the application period of 8 weeks, 62.9 to 77.6 % of chloride extracted in the total chloride profile, and 77.7 to 99.5 % of chloride extracted in the free chloride profile. In particular, the concentration of free chloride at a depth of 7 mm or more from the concrete surface was 0.01 % or less by cement. In addition, it was confirmed that the bound chloride could be extracted by the electrochemical chloride extraction.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.230-237
• /
• 2022

It is essential that service life of reinforced concrete structures in economic and safety aspects should be secured. It is well-known that chloride attack is a typical deterioration mechanism in field concrete structures. To prevent serious accidents like collapse, many studies have been conducted to increase resistance of chloride ingress using concrete mixed with GGBS. The usage of GGBS concrete is nowadays mandatory. Since most concretes in the field are unsaturated, study regarding chloride absorption is necessary, but many studies have focused on the chloride diffusion phenomenon. Methods for evaluating chloride absorption are cost and improper in the field. It is necessary to develop a simple method for evaluating chloride absorption in practice. This study evaluated resistance of chloride ingress in GGBS concretes with impedance measurement and absorption test. From the results, it was confirmed that the contents of absorbed chloride were linearly correlated with the measured electrical resistivities (or conductivities) in the concrete. At the end of the test, the electrical conductivities were 250.8 S/m (w/b=0.4) and 303.1 S/m (w/b=0.6) for PC concretes, and 2.6 S/m (w/b=0.4) and 64.4 S/m (w/b=0.6) for GGBS concretes, respectively. Considering influencing factors for chloride absorption and impedance measurement, chloride ingress into concrete is mainly affected by pore structures due to replacement of GGBS. Especially, formations of pore structure are different with binder, thereby binders should be considered in building reinforced concrete structures exposed to chloride environments.

• Applied Chemistry for Engineering
• /
• v.35 no.4
• /
• pp.296-302
• /
• 2024

An ionic conjugated polymer-iron (III) chloride composite was prepared via in-situ quaternization polymerization of 2-ethynylpyridine (2EP) using iron (III) chloride. Various instrumental methods revealed that the chemical structure of the resulting conjugated polymer (P2EP)-iron (III) chloride composite has the conjugated backbone system having the designed pyridinium ferric chloride complexes. The polymerization mechanism was assumed to be that the activated triple bond of 2-ethynylpyridinium salt, formed at the first reaction step, is easily susceptible to the step-wise polymerization, followed by the same propagation step that contains the propagating macroanion and monomeric 2-ethynylpyridinium salts. The electro-optical and electrochemical properties of the P2EP-FeCl₃ composite were studied. In the UV-visible spectra of P2EP-FeCl₃ composite, the absorption maximum values were 480 nm and 533 nm, and the PL maximum value was 598 nm. The cyclic voltammograms of the P2EP-FeCl₃ composite exhibited irreversible electrochemical behavior between the oxidation and reduction peaks. The kinetics of the redox process of composites were found to be very close to a diffusion-controlled process from the plot of the oxidation current density versus the scan rate.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.28 no.5
• /
• pp.20-29
• /
• 2024

The chloride diffusion coefficient is a critical indicator for assessing the durability of concrete marine substructures. This study develops a prediction model for the chloride diffusion coefficient using data from concrete bridges located in marine exposure zones (atmospheric, splash, tidal), an aspect that has not been considered in previous studies. Chloride profile data obtained from these bridge substructures were utilized. After data preprocessing, machine learning models, including Random Forest (RF), Gradient Boosting Machine (GBM), and K-Nearest Neighbors (KNN), were optimized through hyperparameter tuning. The performance of these models was developed and compared under three different variable sets. The first model uses six variables: water-to-binder (W/B) ratio, cement type, coarse aggregate volume ratio, service life, strength, and exposure environment. The second model excludes the exposure environment, using only the remaining five variables. The third model relies on just three variables: service life, strength, and exposure environment factors that can be obtained from precision safety diagnostics. The results indicate that including the exposure environment significantly enhances model performance for predicting the chloride diffusion coefficient in concrete bridges in marine environments. Additionally, the three variable model demonstrates that effective predictions can be made using only data from precision safety diagnostics.

• Analytical Science and Technology
• /
• v.18 no.5
• /
• pp.376-380
• /
• 2005

Quantitative analysis of silver from the thermal decomposition of chlorinated polymer contained nano silver is described. The chlorine contained in the chlorinated polymer (e.g. PVC) is liberated as hydrochloric acid gas by heating and a lot of silver produces AgCl. $HNO_3$ and $NH_4OH$ were used for dissolving the Ag and the AgCl. The silver complex was formed by $NH_4OH$. Then the complex was decomposed to silver by heating at $500^{\circ}C$ and the Ag was dissolved by dilute $HNO_3$. Recovery of silver in PVC material was 99.0%.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.2
• /
• pp.121-128
• /
• 2005

This study focuses on evaluating the reliability index of a deck of RC slab having chloride contamination and studying the relation of grades of rebar corrosion and the reliability index of a bridge deck For this purpose, first, the failure probability related to flexural strength was calculated using a model for deterioration, which contains the application of deicing salts that usually causes significant long-term deterioration and reduction in the structural safety for strength of structure. And also, according to the depth of covering, the chloride contents depending on time due to depths of RC slab deck, the appearance time for initial corrosion of rebar and the occurrence time for split of covering were investigated using a MCS method.