• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.489-498
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• 2005

Recently, the deterioration of concrete structures have been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the deterioration of concretes have been taken. Among them, it has been often used that surface treatment which cut off the deterioration factors of durability by protecting the surface of concrete. The water proof and repair materials for concrete mainly use organic materials such as epoxy, these materials excel in intial bonding force and resistance to chemical agents. But they cause difference in the modulus of elasticity and the rate of shrinkage and expansion of concrete, and thus result in such problems as scaling and spatting in the progress of time. Therefore in this study it develop the performance Improving agent of concrete surface that can block a deterioration cause such as $CO_2$ gas, chloride ion and water from the outside and enhance waterproofing ability by reinforcing the concrete surface when applying it to concrete structures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.146-147
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• 2021

An increase in carbon emissions leads to the problem of global warming and is an issue to be solved in other countries. The problem of carbon dioxide has many effects not only on global warming but also on people. According to the World Health Organization (WHO), 4.3 million people have died because harmful substances generated indoors cannot be discharged to the outside and accumulate in the human body through the respiratory tract. In response to this situation, in order to reduce the generation of pollutants in the building itself, soak into lightweight bubble concrete to adsorb and purify indoor pollutants, mix charcoal, investigate the appropriate amount and physical characteristics, and check carbon dioxide This is an experiment for grasping the adsorption capacity, and the results are as follows. As the replacement rate of rice husk charcoal increased, the compressive strength tended to decrease, and the carbon dioxide reduction rate tended to increase. It is judged that the charcoal of rice husks shows a low density and the physical adsorption is smooth due to the porous structure. Since it is excellent in the basic physical properties and carbon dioxide adsorption surface of this experiment, it is judged that it has sufficient potential for use as an indoor finishing material.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.639-646
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• 2007

This study performed several tests for the durability of the concrete coated with nano synthesis ceramics which do not contain volatile organic compounds harmful to environment. The tests were adhesion test on dry and humid concrete, SEM test, MIP analysis, carbonation, chloride diffusion by electronic facilitation, freezing-thawing resistance, alkaline resistance, and brine resistance test. In the adhesion test on dry and humid concrete, nano synthesis ceramics coating produced the highest results among all the coatings tested. Nano synthesis ceramics adhered solidly on the concrete surface. The adhesive strength seemed to result from the hydrogen bond between nano synthesis ceramics which are inorganic and generated by hydrolysis and re-condensation reaction and the concrete's hydrates such as calcium silicate aluminate or calcium silicate hydrate. SEM test and MIP analysis results show surface structure with finest crevices pore in the nano synthesis ceramics coating applied concretes. In the carbonation, chloride diffusion, and freezing-thawing resistance tests, the concretes with nano synthesis ceramics coating indicated the best results. Based on these test results, further progress in application of nano synthesis ceramics coatings to various concrete structures including costal structures and sewerage arrangements can be expected.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.961-964
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• 2008

There are researches in progress on ensuring the safety of the high impact concrete in case of fire which is a current rising social problem and this research institute also developed PFB technology, the explosion preventing technology. PFB technology is to apply POSCO E&C Fire Board, a fireproof board, with an adhesive agent on the construction site, and this technology passed 3-hour fireproof test and this technology was proven from a previous research that the temperature of main root is maintained under $200^{\circ}C$. Therefore, tests on basic contents was performed in this research before the actual construction, with a full scale of wooden prototype to apply PFB technology to actual construction sites and the tests were done on the workability of fireproof board, the adhesive power, the resistance against imprint of wooden nail, the heat conductivity and etc. As the results of these tests, PFB technology was proven to have an excellent workability at a construction site and to be easy for processing and also, this technology was proven to have a great resisting power against imprint of wooden nail. Therefore, this research has confirmed that PFB technology has no problem to be applied on a construction site.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.110-116
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• 2013

A concrete structure has become bigger and higher because of development of construction technology and a change in construction environment. Also it tends to focus on repairing, reinforcement and exterior in harmony with environment for structure maintenance and performance improvement. The research is about eco friendly durable painting applicable to concrete structure using civil and architecture. it purpose to improve external beauties and durable problems due to flexibility by variation of temperature, adhesion of exterior wall, crack and delamination in existing organic and mineral painting. For those problems, we made a eco friendly pre-paint that is made with preliminary treatment mixture as a highly enriched waterproof agent and adhesive increasing agent in preprocessing mixture. Then we performed an experiment on durability of prevention neutralization of concrete, durability abrasion, hiding power, adhesion, temperature resistance and resistance to chemical attack. The result of an experiment shows that hiding power is over 0.96 in standard test, durability abrasion test got higher value 1mg than water paint 75mg and tensile strength is 6 times higher than standard waterproof specification.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.120-131
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• 2019

Recently, the level of fine dust and ultrafine dust has reached its highest level, threatening the public's health. If the air purifier was not operated indoors, natural ventilation would not be possible. In this study, photocatalyst is applied to building materials to purify air in a passive manner. In order to use photocatalyst for LEFC(Light Emotion Friendly Concrete), it is necessary to secure self-consolidating capability. Therefore, self-consolidating performance was evaluated by slump test, J-ring test and L-box test with UHPC materials applied. Based on these results, the mixture proportion was determined, and the mechanical performance was evaluated by compressive and flexural tests. Concrete blocks were constructed with a fabrication method that improved the existing process of making LEFC. Also, the concrete block was emptied as a way to reduce the use of expensive photocatalyst. Finally, in order to identify the distribution of TiO₂, an EDS analysis was performed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.353-359
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• 2010

Cementitious matrix based composites are vulnerable to the drying shrinkage crack during the curing process. In this study, the drying shrinkage induced fracture behavior of the fiber reinforced concrete is simulated and the effects of the fiber reinforcement conditions on the fracture characteristics are analysed. The numerical model is composed of conduit elements and rigid-body-spring elements on the identical irregular lattice topology, where the drying shrinkage is presented by the coupling of nonmechanical-mechanical behaviors handled by those respective element types. Semi-discrete fiber elements are applied within the rigid-body-spring network to model the fiber reinforcement. The shrinkage parameters are calibrated through the KS F 2424 free drying shrinkage test simulation and comparison of the time-shrinkage strain curves. Next, the KS F 2595 restrained drying shrinkage test is simulated for various fiber volume fractions and the numerical model is verified by comparison of the crack initiating time with the previous experimental results. In addition, the drying shrinkage cracking phenomenon is analysed with change in the length and the surface shape of the fibers, the measurement of the maximum crack width in the numerical experiment indicates the judgement of the crack controlling effect.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.317-338
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• 2022

Physicochemical characteristics and evaluation were studied by subdividing the concretes, bricks and earth pipes on the site of the Japanese Ministry of General Affairs in Joseon Dynasty, known as modern architecture, into three periods. Concretes showed similar specific gravity and absorption ratio, and large amounts of aggregates, quartz, feldspar, calcite and portlandite were detected. Porosity of the 1907 bricks were higher than those of 1910 and 1950 bricks. All earthen pipe is similar, but the earlier one was found to be more dense. Bricks and earthen pipes are dark red to brown in color within many cracks and pores, but the matrix of the earthen pipe is relatively homogeneous. Quartz, feldspar and hematite are detected in bricks, and mullite is confirmed with quartz and feldspar in earthen pipes, so it is interpreted that the materials have a firing temperature about 1,000 to 1,100℃. Concretes showed similar CaO content, but brick and earthen pipe had low SiO₂ and high Al₂O₃ in the 1907 specimen. However, the materials have high genetic homogeneity based on similar geochemical behaviors. Ultrasonic velocity and rebound hardness of the concrete foundation differed due to the residual state, but indicated relatively weak physical properties. Converting the unconfined compressive strength, the 1st extended area had the highest mean values of 45.30 and 46.33 kgf/cm², and the 2nd extended area showed the lowest mean values (20.05 and 24.76 kgf/cm²). In particular, the low CaO content and absorption ratio, the higher ultrasonic velocity and rebound hardness. It seems that the concrete used in the constructions of the Japanese Ministry of General Affairs in Joseon Dynasty had similar mixing characteristics and relatively constant specifications for each year. It is interpreted that the bricks and earthen pipes were through a similar manufacturing process using almost the same raw materials.

• Land and Housing Review
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• v.14 no.4
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• pp.103-110
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• 2023

People who spend most of their day indoors are continuously exposed to internally and externally generated indoor pollutants. According to a 2022 report from the World Health Organization (WHO), air pollution is the cause of more than 7 million deaths annually worldwide, emphasizing the seriousness of indoor air pollutants. Air pollutants include nitrogen oxides (NOx), formaldehyde (HCHO), and volatile organic compounds (VOCs), which have serious effects on the human body. Photocatalyst is a material that can remove these indoor air pollutants. Photocatalysts not only have the ability to remove dust precursors, but also have antibacterial, sterilizing, and deodorizing functions, making them effective in improving indoor air quality. This study suggests areas and methods in which photocatalysts can be applied to buildings. Fields of application include interior and exterior construction materials such as concrete, as well as organic paints and ventilation devices. If appropriate utilization plans are developed, it may be possible to improve the built environment through reduced indoor and outdoor pollutant levels.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.81-88
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• 2005

The fly ash has been widely used in the latest to complement the performance and economical efficiency of the concrete which uses only a normal portland cement, the pulp ash gained through the incineration of paper sludge is possible to be used as the material of concrete because it contains the properties similar to the previous fly ash in ingredients and physical characteristics. Therefore, this research has tested physical characteristics by replacing 20% of fly ash used with the paper ash to solve the problem which lowers the early strength caused when the fly ash was used. As a result, it showed that the fluidity becomes lower and the compressive strength becomes increased by using paper ash. In addition, after mixing the paper ash with the fly ash, it showed that time and heating amount of the 2nd peak of the minor heat of hydration affecting the revelation of strength was equivalent to the combination for normal portland cement, and also indicated that the compressive strength for 3 days is superior to the combination of the fly ash. Therefore, if the paper ash having a regular fineness is used, it was effective in improving the early strength of concrete used the fly ash.