• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.139-145
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• 2003

Ternary blended concrete, which contains both fly ash and granulated blast furnace slag, has an initial cost effective and is environment friendly. Furthermore, it has a lot of technical advantages such as the improvement of long term compressive strength, high workability, and the reduction of hydration heat. However, as the use and study on the performance of ternary blended concrete is limited, it is worthwhile studying the actual performance of this technology. This study examined the durability performance of ternary blended concrete, compared to binary blended concrete and ordinary portland concrete. It led to the conclusion that ternary blended concrete is very suitable for submerged members under marine environment. However, it should be noticed that ternary blended concrete becomes weak on carbonation, when it is situated on combined deterioration environment of carbonation and chloride. Therefore, the curing duration of ternary blended concrete should be prolonged in order to enhance the resistance of carbonation.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.259-265
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• 2014

This study is to analyze durability of water-repellent paints mixed with water-repellents as outer surface finishing materials, and evaluate its feasibility. General functions and water-repelling effects were tested, and the feasibility was evaluated based on the test results. The experimental results of heat conduction durability, air permeability, absorption, and bond strength suggested that water-repellent paints mixed with water-repellents were suitable for finishing materials. Considering overall general durability performances, stable mixing ratios were 2, 5, and 8%.

• Advances in concrete construction
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• v.5 no.4
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• pp.313-330
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• 2017

Geopolymer is a sustainable concrete, replaces traditional cement concrete using alternative sustainable construction materials as binders and alkaline solution as alkaline activator. This paper presents the strength characteristics of geopolymer concrete (GPC) developed with fly ash and GGBS as binders, combined Sodium silicate ($Na_2SiO_3$) and Sodium Hydroxide (NaOH) solution as alkaline activators. The parameters considered in this research work are proportions of fly ash and GGBS (70-30 and 50-50), curing conditions (Outdoor curing and oven curing at $600^{\circ}C$ for 24 hours), two grades of concrete (GPC20 and GPC50). The mechanical properties such as compressive strength, split tensile strength and flexural strength along with durability characteristics were determined. For studying the durability characteristics of geopolymer concrete 5% $H_2SO_4$ solutions was used and the specimens were immersed up to an exposure period of 56 days. The main parameters considered in this study were Acid Mass Loss Factor (AMLF), Acid Strength Loss Factor (ASLF) and products of degradation. The results conclude that GPC with sufficient strength can be developed even under Outdoor curing using fly ash and GGBS combination i.e., without the need for any heat curing.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.5
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• pp.467-473
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• 2019

In this study, approached to improve durability of the multi-functional nano-pattern fabricated on the curved lens surface using nanoimprint lithography (NIL) was proposed, and the effects of the proposed methods on functionality after wear test were examined. To improve the mechanical property of ultraviolet(UV)-curable resin, UV-NIL was conducted at the elevated temperature around $60^{\circ}C$. In addition, micro/nano hierarchical structures was fabricated on the lens surface with a durable film mold. Analysis on the worn surfaces of nano-hole pattern and hierarchical structures and measurements on the static water contact angle and critical water volume for roll-off indicated that the UV curing process with elevated temperature is effective to maintain wettability by increasing hardness of resin. Also, it was found that the micro-scale pattern is effective to protect nano-pattern from damage during wear test.

• Elastomers and Composites
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• v.55 no.4
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• pp.270-276
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• 2020

The long-term durability of an FKM O-ring used as parts of a hydrogen station was investigated by exposing it to high-pressure gaseous hydrogen for 1, 3, and 7 days at room temperature. Changes in its sealing force were subsequently measured at 150℃ using intermittent compression stress relaxation (CSR). No changes in the tensile properties of FKM O-ring were observed, but its initial and overall sealing forces at 150℃ significantly decreased with increasing exposure time to hydrogen gas. Microvoid formation in the FKM O-ring upon exposure to high-pressure hydrogen was minimized over time after the ring was exposed to atmospheric pressure at room temperature, which prevented changes in its tensile properties. However, applying heat accelerated FKM O-ring oxidation, which decreased its sealing force. These results indicated that identifying changes in the sealing force of rubber materials using intermittent CSR is not sufficient for monitoring changes in mechanical properties under high-pressure hydrogen atmospheres; however, it is suitable for evaluating the long-term durability of sealing materials for hydrogen station applications under similar conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.725-728
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• 1999

The bridge slab of express railway was designed for high strength concrete (design strength 400kgf/$\textrm{cm}^2$). In case the slab is made with the concrete using type I cement, used much amount of cement can cause cracks through concrete by hydration heat or dry shrinkage. In this study we targeted to solve above problems using type III cement. We could decrease the cement ratio in concrete using type III cement than type I cement. The concrete using type III cement showed good workability and compressive strength, and showed better properties in hydration heat and dry shrinkage than that using type I cement

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.238-242
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• 1994

Recently, construction of mass concrete structures except Dam are increased very often. Generation heat due to the hydrating reaction of mass concrete is generally larger than the heat released to the air, foundations and the exist structures. Therefore, internal temperature of mass concrete is remarkably risen and temperature gap between center and surface is extended by various effect. It this gap get large, the crack may be occurred. This crack must be controlled as little as possible to ensure the soundness and durability of structure. Firstly, Temperature rising history of Mass concrete is expected correctly to constrain the crack of mass concrete. So, objectives of this research is to quantify the effects of hydration temperature for the purpose of evaluating accurately the temperature history of mass concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.556-559
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• 2004

In this Paper, concrete durability, coefficient variation of compressive strength, and hydration heat development characteristics of concrete using different types binder for 2nd Phase Construction in IIA were investigated. The experimental results show that the coefficient variation of compressive strength decreased with the slag cement when compared with the replacement of granulated blast furnace slag powder. And the diffusion coefficient of chloride ion decreased with use of a blended cement when compared with using a only portland cement. Also the type of low heat cement is very suitable to reduce the thermal crack caused by hydration heat development.

• Toxicological Research
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• v.22 no.3
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• pp.237-244
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• 2006

Two kinds of sepiolite, a $500^{\circ}C$ heat-treated sepiolite, and a $700^{\circ}C$ heat-treated sepiolite were analyzed for their physicochemical properties. After these sepiolites were instilled into rat lungs, the effects of the substances on lung pathological changes were evaluated. The lungs instilled with sepiolite increased their weight compared with the unexposed control. The pathological examination further showed increased legions of granuloma with early fibrosis. The heat treated sepiolites, however, did not show any toxicological differences from the untreated sepiolites. Thus chronic experiments are needed to evaluate the durability of mineral fibers, which is an essential experiment for evaluating biopersistence of fibers in lungs.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.595-598
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• 2005

Recently, owing to the development of industry and the improvement of building techniques, the concrete structure is becoming larger and higher. In hardening these large concrete, the heat of hydration gives rise to considerable thermal stress depending on the size and environmental condition of concrete, which might cause thermal cracking. Especially, the crack may cause severe damage to the safety and the durability of concrete structure. This study is investigated the thermal properties of concrete according to several binder conditions, such as OPC, Belite rich cement(BRC), slag cement(SC), blast furnace slag (BFS) added cement, fly ash added cement and BFS-fly ash added cement. As a result of this study, the concrete made with BRC, fly ash($25\%$) added cement and BFS($35\%$)-fly ash($15\%$) added cement gets superior effect in the control of heat hydration.