• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.257-264
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• 2002

This study presents a life-cycle cost (LCC) effectiveness of a concrete with lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. In this study, an optimum design for minimizing the life-cycle cost of concrete slab bridges is performed to evaluate the life cycle cost effectiveness of the lightweight concrete relative to conventional one from the standpoint of the value engineering. The data of physical properties for new concrete can be obtained from basic experimental researches. The material properties of conventional one are acquired by various reports. This study presents a LCC effectiveness of newly developed concrete, which is made by artificial lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. From the results of the numerical investigation, it may be positively stated that the new concrete lead to, the longer span length, the more economical slab bridges compared with structures using general concrete.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.1
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• pp.34-41
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• 2002

There m many noise sources in living environment. Especially, noise that happen in apartment or tenement house may make neighborhood serious troubles. Thus, the development of new materials to reduce and improve the living noises is required. During past decade, various methodologies have been developed and researched to reduce and improve the living noises. However, there are many problems to apply these methodologies to practical our environment. In this thesis, we develop the new artificial material supporting high porous materials and lower pressure density to improve the problem caused in the safety design and sound absorbing material. To prove the efficiency of the developed methodology, we compare our methodology with conventional methodologies and also suggest an alternative methodology to contribute quiet life environments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.186-193
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• 1998

The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.233-242
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• 2002

This study is to investigate experimentally the shear capacity of high-strength lightweight-aggregate reinforced concrete beams subjected to monotonic loading. Ten beams made of fly-ash artificial lightweight high-strength concrete were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were longitudinal reinforcement ratio; which variabled (between 0.83 and 1.66 percent), shear span-to-depth ratio (a/d=1.5, 2.5 and 3.5), and web reinforcement(0, 0.137, 0.275 and 0.554 percent). Six of the test beams had no web reinforcement and the other six had web reinforcement along the entire length of the beam. Most of beams failed brittly by distinct diagonal shear crack, and have reserved shear strength due to the lack of additional resisting effect by aggregate interlocking action after diagonal cracking. Test results indicate that the ACI Building Code predictions of Eq. (11-3) and (11-5) for lightweight concretes are unconservative for beams with tensile steel ratio of 1.66, a/d ratios greater than 2.5 without web reinforcement. Through a more rational approach to compute the contribution of concrete to the shear capacity, a postcracking shear strength in concrete is observed.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.311-311
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• 2023

파형강관은 아연도금강판을 물결모양으로 성형하여 나선형으로 조관한 연성관으로 콘크리트 흄관을 대체하여 각종 토목공사의 우수 및 하수관으로 주로 사용되고 있다. 파형강관은 강판에 물결 형상을 성형하여 내하력을 부여하였기 때문에 높은 강도를 지니고 있고, 경량이고 유연성이 있어 기초공사가 쉽고 현장에서의 운반 및 보관이 용이하여 그 활용이 점차 확대되고 있다. 이러한 파형강관의 내/외부에 기능성 고분자 복합 Polymer(다중필름)을 코팅하여 일반 파형강관 대비 더 높은 내식성 및 내마모성을 구현한 제품을 NPE 피복 파형강관이라 하며, 내부에 평판을 2중으로 결합하여 일반 파형강관 대비 통수능력을 개선한 파형강관을 내부평활 파형강관이라고 한다. 최근 파형강관의 활용이 점차 확대되고 있음에도 불구하고, 파형강관에 국한된 수리역학적 특성에 관한 연구는 미흡한 실정이며, 그마저도 주로 만관 혹은 만관에 가까운 상태에서의 흐름만이 고려되어 왔다. 하지만 대구경의 파형 강관이 우수 배관 및 하수 처리를 위하여 설치될 경우 개수로 흐름이 발생하게 된다. 이에, NPE 피복 파형강관과 내부평활 파형강관 내에서의 개수로 흐름을 다양한 유량 및 수심 변화를 통하여 생성하였으며, 각각의 수리학적 조건에서 통수능을 결정하는데 중요한 상수인 조도계수를 수리 실험을 실시하여 결정하였다. 이는 현재 국내에서 생산되고 있는 NPE 피복 파형강관과 내부 평활강관의 활용에 있어서 국제 경쟁력을 높이는데 큰 도움이 될 것이라 사료된다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.83-84
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• 2022

Zero-energy construction is being emphasized due to environmental pollution. However, in the case of external insulation using organic insulation with good insulation performance, there are many studies on inorganic insulation as it shows limitations on fire stability. In addition, as the demand for stone for exterior walls increases, Cellular Light -weight Concrete(CLC) with polymer is used to supplement fire stability and insulation performance, and the construction of stone is complemented by combining organic insulation, inorganic insulation, and stone. In this study, the compressive strength and adhesion in tension of CLC are studied. As a result of the experiment, the compressive strength of 28 days according to the polymer addition rate did not change. The adhesion in tension according to the polymer addition rate tends to increase as the addition rate increases. The target adhesion in tension is 0.8 MPa, but the maximum value of the experiment did not reach the target value, and further research was needed to combine to maintain the density and improve the adhesion in tension.

• Journal of the Korea Institute of Building Construction
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• v.23 no.5
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• pp.509-517
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• 2023

The surge in FRP(Fiber Reinforced Plastic) research signifies the industry's pursuit to counteract the longstanding issue of rebar corrosion. Notably, Carbon Fiber Reinforced Plastic(CFRP) emerges as a commendable alternative, given its superior resistance to both corrosion and chemical interactions, thus positing itself as a potential replacement for traditional steel rebars. However, the layered composition of fibers and resin in CFRP flags a notable susceptibility to elevated temperatures. Despite its promise, comprehensive studies elucidating the full spectrum of CFRP properties remain ongoing. In this investigative study, we meticulously assessed the bond strength of CFRP post-exposure to high thermal conditions. Our findings underscored a parity in bond strength amongst silica sand-coated CFRP, rib-type CFRP, and Glass Fiber Reinforced Plastic(GFRP).

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.310-323
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• 1983

To study the effect of foaming agent on the production and property of light weight concrete, the tests of compressive, tensile, bending strengths and absorption rates of mortar were done under the different mixing ratio with J, A and D foaming agents. The results obtained were summarized as follows : 1. The strengths were decreased in richer mixing ratio and more addition of foaming agent. The decrease of strengths was the greatest at the level of 0.75% of foaming agent. The decreasing rate of strengths was in order of J, A and D foaming agent. 2. At the mixing ratio of 1:1, ${\sigma}_{28}$ and 0.75% of foaming agent, the compressive strength was decreased up to 34.9% by D, 47.8% by A and 86.8% by J foaming agent, respectively, the tensile strength was decreased up to 14.8% by D, 20.2% by A and 77.9% by J foaming agent, respectively, bending strength was decreased up to 19.9% by D, 35.0% by A and 79.1% by J foaming agent, respectively. The decrease of compressive strength was more severe than that of tensile and bending strengths. 3. The absorption rates were increased in poorer mixing ratio and more addition of foaming agent. The absorption rate was significantly higher at the early stage of immersed water. The absorption rate was in order of J, A and D foaming agent. 4. The decrease of strengths was inevitable in cement-mortar with foaming agent, but the cement mortar with foaming agent has such the properties of the light-weight, lnsulation, Keeping-warmth, sound proof and fire-proof that if could be utilized to the constructions which need low strengths.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.493-500
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• 2004

FREP(Fiber Reinforced Epoxy Panel) are used for strengthening the damaged RC beams due to its good tensile strength, low weight, resistance to corrosion, and easy applicability. This study sets up structure equation for FREP bending reinforcement before and during the usage of RC beam. It finds the difference and finds the mechanical characteristics of rip-off failure that is caused by stress concentration in reinforcement material cutting part to estimate the performance of bending reinforcement. The result of this research can be summarized as two main consequences. The main failure of FREP reinforced concrete beam is rip-off failure and it evaluated rip-off failure of RC reinforcing bean based on the test and analytical conditions of this study. It found that stress was concentrated due to rapid change of bending rigidity in reinforced cutting part as a result of excessive reinforcement thickness of FREP. It resulted in rip-off failure. It means that it should evaluate the rip-off failure when designing reinforcement. It analyzed the reinforcement effect according to reinforced period for FREP. It found that reinforcement effect of P-Type that was reinforced during the usage decreased compared to I-Type that was reinforced before the usage. So when reinforcing a existing structure that is being used, it should consider the stress that is produced due to the fixed load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.1-8
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• 2018

FRP is a new material that is light, has high strength and high durability, and is emerging as a third construction material inside and outside of countries. However, very few studies have been done on curved FRP construction materials that can be used for tunnels or arched bridges. Because a small composite panel specimen is smaller than a full-size specimen, it can be used in a variety of experiments under different conditions. Therefore, in this study, experiments were performed on a void section, a solid section, a connected solid section, and a sand-coating solid section. The results of the experiment show that the connection of composite curved panels with longitudinal connections provides almost equivalent performance to that of a single panel. However, it is necessary to strengthen the connections, since the connections that are most susceptible to damage will break first.