• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.955-958
• /
• 2006

The purpose of this study is to find ways of recycling a great amount of gypsum as by-product from the manufacture of phosphate fertilizer. For the purpose, this researcher investigated physical properties of light weight Porous material using waste gypsum and a foaming agent, Sodium n-dodecyl Sulfate to utilize it as a interior material of construction. To determine such properties, the study examined pore size distribution and pore rate in accordance with contents of Sodium n-dodecyl Sulfate added. Then expanded vermiculite as light-weight aggregate was also added, when pore size distribution, pore rate and sound absorption rate were surveyed and measured.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.441-444
• /
• 2010

대공간 구조물과 초고층 빌딩에 있어 건축물의 자중 감소에 대한 요구가 늘어나고 있으며 이에 대한 가장 효과적인 방법 중 하나는 경량 콘크리트를 사용하는 것이다. 본 연구는 최외단 철근의 순인장 변형률에 따른 경량콘크리트 보의 휨 거동 및 휨 성능을 평가하는 것에 그 목적이 있다. 크기와 형상이 동일한 보통중량 콘크리트 보 1개와 경량 콘크리트 보 4개의 총 5개 시험체를 제작하여 최외단 철근의 순인장 변형률을 변수로 실험을 수행하였으며 이를 통해 순인장 변형률에 따른 경량콘크리트 보의 강도와 연성의 변화를 분석하였다. 실험 결과 최외단 철근의 순인장 변형률이 증가할수록 시험체의 연성비는 증가하였으며 최대하중과 강성은 감소하였다. 특히 순인장 변형률 0.005 이상에서 연성지수 2 이상을 확보할 수 있었다.

• Journal of Environmental Impact Assessment
• /
• v.20 no.6
• /
• pp.815-821
• /
• 2011

This study aims to estimate the biological decomposition capacity of MPC(Microorganism Porous-Concrete). MPC has specific surface area formed by inside pores, and bio compound was added to those pores to reduce pollutants loading. To evaluate the water purification capacity of MPC, we carried out the comparative studies using different media types [GPC(General Porous-concrete), CPC(Compound porous-concrete), LPC(Lightweight aggregate porous-concrete)] under the condition of CFSTR, and different retention times (30, 60 and 120 min). We also estimated the purification capacity of MPC under different concentrations of pollutant loadings. The MPC showed higher efficiency in water purification function than other conventional porous concretes with efficient decrease rates of SS, BOD, COD, and nutrient concentrations. In the comparison experiment for different retention times, MPC showed the highest removal efficiency for all tested pollutants in the longest retention time(120 min). In the long period test, the removal efficiencies of MPC concrete were high until 100 days after the set up of the operation, but began to decrease. Outflow flux was invariable compared with inflow flux so that extra detention time for media fouling such as back washing is not needed. But the results suggested that appropriate management is necessary for long-term operation of MPC. As the final outcome, MPC using bio organisms is considered to be efficient for stream water purification when they used as substrates for artificial river structure.

• Korean Journal of Agricultural Science
• /
• v.25 no.2
• /
• pp.271-277
• /
• 1998

This study was performed to evaluate the stress-strain properties of surlightweight polymer concrete using synthetic lightweight aggregates. The following conclusions were drawn; 1. The dynamic modulus of elasticity was in the range of $1.514{\times}10^5{\sim}1.916{\times}10^5kgf/cm^2$, which was approximately 48~96% of that of the normal cement concrete. It was showed larger with the decrease of synthetic lightweight fine aggregate. 2. The static modulus of elasticity was in the range of $2.552{\times}10^4{\sim}4.386{\times}10^4kgf/cm^2$, which was showed lower compared to that of the normal cement concrete. The poisson's number of surlightweight polymer concrete was less than that of the normal cement concrete. 3. The stress-strain curves of surlightweight polymer concrete were showed smaller with the increase of expanded clay.

• Steel and Composite Structures
• /
• v.46 no.6
• /
• pp.745-757
• /
• 2023

In order to study the fatigue performance of the flat steel plate-lightweight aggregate concrete hollow composite bridge slab subjected to fatigue load, both static test on two specimens and fatigue test on six specimens were conducted. The effects of the arrangement of the steel pipes, the amplitude of the fatigue load and the upper limit as well as lower limit of fatigue load on failure performance were investigated. Besides, for specimens in fatigue test, strains of the concrete, residual deflection, bending stiffness, residual bearing capacity and dynamic response were analyzed. Test results showed that the specimens failed in the fracture of the bottom flat steel plate regardless of the arrangement of the steel pipes. Moreover, the fatigue loading cycles of composite slab were mainly controlled by the amplitude of the fatigue load, but the influences of upper limit and lower limit of fatigue load on fatigue life was slight. The fatigue life of the composite bridge slabs can be determined by the fatigue strength of bottom flat steel plate, which can be calculated by the method of allowable stress amplitude in steel structure design code.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.3
• /
• pp.22-29
• /
• 2015

In this study, we tested to develop and apply structural insulation performance improvement concrete to field, which had compressive strength in 24 MPa and thermal conductivity twice as much as normal concrete. After experiment about slump and air contents, combination product of Plain and calcined diatomite powder showed reduction of slump and air contents and combination product with micro foam cell admixture, we cannot find result of slump and air contents reduction. Unit weight of combination product with insulation performance improvement materials decreased more than that of Plain. In the test of compressive strength, compressive strength of insulation performance improvement concrete decreased more than that of Plain but was content with 24 MPa. thermal conductivity of insulation performance improvement concrete tended to decrease. Freezing and thawing resistance of insulation performance improvement concrete was similar to that of Plain. In carbonation resistance test, combination product with calcined diatomite powder showed the result which was similar to that of Plain. In carbonation resistance test, combination product with micro foam cell admixture showed a increase compared to that of Plain and length variation of combination product generally increased.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.39 no.1
• /
• pp.75-82
• /
• 1997

건설기술과 산업의 발전에 따라 구조물은 대형화되어 가고, 건설공사의 급격한 팽창으로 골재 수용량이 급증함에 따라 천연골재자원은 점차 부족현상을 면치 못할 처지에 있다. 또한, 무리한 천연골재의 채취는 자연환경을 훼손시킬 뿐만 아니라 자연보호 측면에서도 심각한 공해문제로 대두되고 있어 공급량 부족현상은 날로 심화되고 있다. 이에 세계 몇몇 나라에세는 산업부산물을 이용한 골재 생산으로 공해예방과 폐기물 활용방법을 연구하고 있다. 산업부산물중 플라이 애쉬 생산량은 전 세계적으로 매년 약 2억여톤에 달하고 있으나 이중 일부만 활용되고 있는 실정이다. 이와같은 부산물을 활용하기 위한 일환으로 산업부산물인 PFA(Pulverized Fuel Ash)로 만든 인공경량골재의 년생산량이 영국은 600,000$m^3$, 미국은 300,000$m^3$이며, 매년 증가주세에 있다. 고성능 경량골재 콘크리트는 단위중량의 증가없이 내구성과 강도를 향상시켜 실용화 측면에서 경제적인 효과가 있으며, 플라이 애쉬로 만든 경량골재는 시멘트와의 친화력이나 접착면에서 우수한 것으로 알려져 있다. 본 시험에 사용한 골재는 플라이 애쉬로 만든 인공경량 조골재와 강모래이고, 결합제로서 프틀랜드 시멘트를 사용하였다. 부수적인 결합재로서는 플라이 애쉬, 슬래그, 실리카 흄을 사용하였으며, 고성능 경량골재 콘크리트를 개발코자 재령 28일과 180일의 압축강도가 각각 50MPa와 60MPa가 되도록 배합설계를 하였다. 본 연구에서는 플라이 애쉬, 슬래그, 시리카 흄과 같은 산업부산물을 혼입했을때 경량골재 콘크리트의 압축강도, 휨강도, 동탄성계수, 공극체적, 공극률, 단위중량, 공극 크기별 분포등의 변화를 실험적으로 구명하여 재반 구조용 콘크리트에 활용하기 위한 기초자료를 마련코저 한다.있어 특정한 발육단계의 난포 사망기전을 연구하기 어렵다. 또한 난포는 생체 내에서 다양한 호르몬을 동시에 분비하기 때문에 특정한 난소국부호르몬이 사망기전에 미치는 영향을 조사하기 힘든 점이 있다. 최근 들어 난포체외배양이 다양하게 개발되면서, 이러한 어려운 점을 극복할 수 있게 되었다. 본 논문은 각 발육단계의 난포를 절단해 체외배양하면서, apoptosis DNA 절단 현상을 이용하여 각종 난소국부 호르몬들이 난포발육단계별로 사망기전에 미치는 영향을 요약해 보였다. 난포는 발육하면서 점차 복잡한 호르몬 경로를 생존을 위해 필요로 한다. Prevulatory난포생존에 필요한 난소국부호르몬들은 early antral 단계의 난포에서는 그 미치는 영향이 감소되다가 preantral단계의 난포에서는 영향을 전혀 미치지 못했다. 단지 예외는 cGMP처리로써, 세포내 cGMP수준을 일정하게 유지시켜주는 것이 난포발육단계에 무관하게 생존에 중요한 인자로, 장래 연구는 난포 세포내의 cGMP수준을 조절하는 기작을 규명하는데 있을 것이다.인정되지 않았다. 7. 농지보전 처리구인 배수구와 초생수로구는 비처리구에 비해 낮은 침두 유출량과 낮은 토양유실량을 나타내었다.구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가

• Journal of the Korea Concrete Institute
• /
• v.22 no.6
• /
• pp.851-858
• /
• 2010

In this study, waste glass and bottom ash were used as basic materials in order to secure a recycling technology of by-products which was mostly discarded and reclaimed. In addition, because softening point of waste glass is less than $700^{\circ}C$ and bottom ash includes combustible material, it was possible to manufacture low-temperature sintering lightweight aggregates for energy saving at $800{\sim}900^{\circ}C$ that it is as much as 20~30% lower than sintering temperature of existing lightweight aggregates. Thermal conductivity of newly-developed lightweight aggregates was 0.056~0.105W/m. K and its porosity was 40.36~84.89%. A coefficient of correlation between thermal conductivity and porosity was -0.97, it showed very high negative correlationship. With this, we were able to verify that porosity is key factor to affect thermal conductivity. Microstructure of lightweight aggregates by $CaCO_3$ content and replacement ratio of bottom ash in the variation of temperature were that $CaCO_3$ content increased along with pore size while replacement ratio of bottom ash increased as pore size decreased. Specially, most pores were open pore instead of closed pore of globular shape when replacement ratio of bottom ash was 30%, and pore size was small about 1/10~1/5 as compared with case in bottom ash 0~20%. In addition, open pore shapes were remarkably more irregular form of open pore in $900^{\circ}C$ than $700^{\circ}C$ or $800^{\circ}C$ when replacement ratio of bottom ash was 30%. We reasoned hereby that these results will influence on absorption increase, strength and thermal conductivity decrease of lightweight aggregates.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.74-79
• /
• 2022

In this study, the effect of a sudden decrease in internal humidity and a decrease in hydration level due to the tight internal structure of high-strength concrete and cement composites was investigated. To verify the change in the internal Si hydration, waste glass foam beads were used as a lightweight aggregate, and the internal unreacted hydrate reduction and hydrate formation tendency were identified over the mid- to long-term. Waste glass foam beads were mixed with 5, 10, and 20 %, and were used by pre-wetting. As the mixing rate of the waste glass foamed beads increased, the strength showed a tendency to decrease. In addition, when the mixing amount of pre-wetted waste glass foam beads increases inside through XRD analysis, TGA analysis, and Si NMR analysis, it is judged that the hydration degree of internal Si is different because moisture is supplied to the paste.

• Advances in concrete construction
• /
• v.11 no.5
• /
• pp.409-417
• /
• 2021

The incorporation of non-biodegradable tyre waste in cement-based material has gained more interest towards sustainable construction these days. Crumb rubber (CR) from waste tyre is an alternative for sand replacement in low strength applications. Many researchers have studied CR cement-based materials produced by normal mixing (NM) method and reported a significant decrease in compressive strength due to CR. To compensate this strength loss, this research aims to study the innovative incorporation of CR in cement composite via the preplaced mixing (PM) method. In this investigation, cement composite was produced with NM and PM methods by replacing sand with 0%, 50%, and 100% CR by volume. The test results showed no significant difference in terms of densities of cement composite prepared with both mixing methods. However, cement composite prepared with PM method had lower strength reduction (about 10%) and lowered drying shrinkage (about 20%). In addition, the sound absorption coefficient and noise reduction coefficient of CR cement composite prepared by PM method were in similar range as those prepared with NM method. Overall, the results demonstrate that the PM method is promising, and the maximum replacement level of 50% is recommended for CR in the cement composite.