• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.236-237
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• 2018

The aim of the research is evaluating a fundamental properties of mortar with atomized molten slag to develop a hardener for dry soil paving concrete. According to the analyzing results, comparing OPC, more favorable strength characteristics were obtained, while it showed rapid setting when the mixture contained more than 10 %. Therefore, when the atomized molten slag is used as a hardener, appropriate retarding process is needed.

• Journal of the Korea Institute of Building Construction
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• v.6 no.4 s.22
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• pp.93-98
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• 2006

Admixture materials are used in mixing concrete or mortar to improve quality and performance of the concrete. This study examines the potential use of talc as a substitute for cement, the benefits of recycling waste resources for economical efficiency and quality improvement of concrete. The test was carried out by replacing the plain mix with fine grains of talc at the rate of 10%, 20%, and 30%. Talc was divided into three groups depending on the degree of pulverizing. For wet concrete, porosity, slump, bleeding per unit, and setting time by penetration resistance were measured; similarly, for dry concrete, strength and watertight Property were tested. Test results showed that the amount of bleeding and setting time could be shortened, but the strength and watertight proofing severely deteriorated. However, at the replacement rate of 10%, talc showed equal performance with the plain at all degrees of pulverization, which suggests its potential use as admixture material.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.113-120
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• 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 of Building Construction
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• v.16 no.6
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• pp.561-569
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• 2016

Concrete is cheap, easy to deal with, and the quality is satisfactory. Also, it is one of the easiest materials to get because chemical composition of cement is similar to chemical composition of surface. On the other hand, it is so vulnerable to transform because of weak binding capacity and low binding energy that it produces cracks. Cracks decline durability, usability, safety of structures and damage exterior. In order to decline drying shrinkage crack, this study used shrinkage reducing typed Superplasticizer, which is combination of and water-reducing agent for convenience, different with existing study using AE agent, water-reducing agent, shrinkage reducing agent,. Considering SRS field application possibility, this study planned to mix concrete and mortar generally used in ready-mixed concrete company and did basic experiment depending on a change of SRS content ratio and admixture. Based on the experiment result. It is judged that SRS admixture 2% is proper ratio when Given the intensity and length change. Also mass combination will conduct follow-up studies.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.490-502
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• 2012

The use of recycled aggregate, even for low-performance concrete, has been very limited because recycled aggregate, which contains a large amount of old mortar, is very low in quality. To produce a high-quality recycled aggregate, removing the paste that adheres to the recycled aggregate is very important. We have conducted research on a complex abrasion method, which removes the component of cement paste from recycled fine aggregate by using both a low-speed wet abrasion crusher as a mechanical process and neutralization as chemical processes, and well as research on the optimal manufacturing condition of recycled fine aggregates. Subsequently, we evaluated the quality of recycled fine aggregate manufactured using these methods, and tested the specimen made by this aggregate. As a result, it was found that recycled fine aggregates produced by considering the aforementioned optimal abrasion condition with the use of sulfuric acid as reactant showed excellent quality, recording a dry density of 2.4 and an absorption ratio of 2.94. Furthermore, it was discovered that gypsum, which is a reaction product occurring in the process, did not significantly affect the quality of aggregates. Furthermore, the test of mortar using this aggregate, when gypsum was included as a reaction product, showed no obvious retarding effect. However, the test sample containing gypsum recorded a long-term strength of 25.7MPa, whereas the test sample that did not contain gypsum posted a long-term strength of 29.4MPa. Thus, it is thought to be necessary to conduct additional research into the soundness and durability because it showed a clear reduction of strength.

• Journal of the Korea Concrete Institute
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• v.14 no.2
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• pp.164-170
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• 2002

Effect of the polymer-binder ratio and slag content on the properties of combined wet/dry-cured polymer-modified mortars using granulated blast-furnace slag are examined. Results shows that the flexural and compressive strengths of polymer-modified mortar using the slag tend to increase with increasing slag content, and reaches a maximum at a slag content of 40 ％, and is inclined to increase with increasing polymer-binder ratio. Water absorption, carbonation depth and chloride ion penetration depth tend to decrease with increasing polymer-binder ratio and slag content. Accordingly, the incorporation of slag into polymer-modified mortars at a slag content of 40％ is recommended for a combined wet/dry curing regardless of the types of polymer.

• Journal of the Korean Geotechnical Society
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• v.32 no.5
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• pp.49-55
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• 2016

This study aims to present the practical Nitrogen monoxide (NO) removal capacity of cement mortar with Titanium dioxide ($TiO_2$) which is one of the paving materials by considering the environment of pavement in urban areas. NO removal capacity test under designated conditions of humidity of inflow gas and the test with variation of the degree of saturation of specimen were conducted. In the test for humidity, dry specimen is subject to the test and NO removal ratio was observed. Humidity-NO removal ratio curve is a log normal distribution in shape, and the maximum NO removal ratio appears at specific humidity. NO removal capacity test relying on the degree of saturation was carried out with wet specimen to reflect the unsaturated pavement by rainfall and domestic sewage. Wet specimen presents less NO removal capacity than dry specimen and the recovering evolution of NO removal capacity follows evaporation. Moreover, $TiO_2$ under the specific depth of specimen hardly contributes to NO removal capacity.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.12-13
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• 2021

Methods for the manufacture, erection, and assembly of heavy frame modules were proposed. Interferences among precast members were prevented by using bolted metal plates for dry precast beam-to-column joints during assembly with a clearance for tolerance implementing grouted concrete filler plates instead of metal filler plates. Clearances for tolerances were provided to avoid conflictions among components during erection phases. These gaps were, then, grouted by high-strength mortar. The constructability of new connections of a beam-to-column joint using bolted metal plates for precast structures was examined using a full-scale assembly test in which practical observations indicated that members could be aligned and placed accurately in both horizontal and vertical directions, leading to a fast and convenient assembling. Bolt holes of the endplate were properly aligned using couplers with 30 mm fastened length embedded in the columns. The assembly test demonstrated the erection safety and structural stability of the proposed joints that were without filler plates when they were subjected to heavy loads at the time of their erection. The facile and rapid assembly of precast beam-to-column connections with a 30 mm tolerance was observed. The proposed assembly method is rapid, sustainable, and resilient, replacing the conventional methods of concrete frame construction, offering a connection that can be used in constructing infrastructure, such as buildings and pipe-rack frames.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.197-200
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• 2006

The ingress of chloride ions plays a crucial role for service life design of reinforced concrete structures. In view of durability design of concrete structures under marine environment, one of the most essential parameters is the surface chloride content of concrete. However, on the basis of the results of in-situ investigation, this value has been determining in the numerous studies on the durability design of concrete structures. Hence, it is necessary to confirm the range of the surface chloride content in order to establish a unified durability design system of concrete. This study suggests a rational and practical way to calculate the maximum surface chloride content of submerged concrete under marine environment. This approach starts with the calculation of the amount of chloride ingredients in normal sea water. The capillary pore structure is modeled by numerical simulation model HYMOSTRUC and it is assumed to be completely saturated by the salt ingredients of sea water. In order to validate this approach, the total chloride content of the mortar and concrete slim disc specimen was measured after the immersion into the artificial sea water solution. Additionally, the theoretical, the experimental and in-situ investigation results of other researchers are compiled and analyzed. Based on this approach, it will follow to calculate the maximum surface chloride content of concrete at tidal zone, where the environment can be considered as a condition of dry-wetting cycles.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.21-26
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• 2004

This study deals with the Hydrated Ability of the Ready-Mixed Concrete's Sludge which is the recycling technology of that sludge. The experiment gathers sludge from Ready-mixed factory. shatters these into pieces in dry condition and understands the differences between current using Portland cement. And then. this examines the possibility of the recycle as a bonding agent through the Compressive Strength and considers the recovery of the hydration. This experiment concludes the same Chemical Composition with the normal Portland cement. while. under the appropriate procedure in hydration recovery. this sludge can be used as the bonding agent in cement. The chemical composition of solid Remicon sludge shows that it has 1.8 times $SiO_2$ than the normal Portland cement. meaning lots of aggregate in Remicon sludge. Also. the specific gravity of Remicon sluge increases with the rise of Baking Temperature and has no difference between 2.77 and 2.94. The mortar flow used for combining the baking material of Remicon sludge does was not changed and is the highest between $750^{\circ}C{\cdot}120min\;and\;800^{\circ}C{\cdot}180min$. Additionally. the Compressive Strength increases with the age, certifying the same Hydrated Ability like cement and the best condition for hydration is $750^{\circ}C{\cdot}120min.$