• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.105-112
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• 2019

Fine aggregate made of ferronickel slag(FNS) is similar to natural fine aggregates and is used in concrete structures both domestically and abroad, but its applications and research areas are limited. In this research, in order to expand the availability of FNS and improve the performance of cement mortar products, the applicability of FNS on dry mortar for floor was examined. Experimental results show that FNS improves flow of cement mortar because it has low absorption rate, spherical shape, and glassy surface. Also, the high stiffness of the FNS aggregate itself is considered to contribute to the improvement of cement mortar quality such as crack reduction by improving the compressive strength and shrinkage reducing. In addition, when FNS fine aggregate is applied, it was possible to secure the impact sound insulation performance equal to or higher than that of mortar using natural fine aggregate.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.241-249
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• 2023

The objective of this research was to engineer a tile module that could efficiently curtail the incidence of tile defects during the construction phase. To assess the potential diminution in defect manifestation, we executed experiments centered on surface condition, the variation in mass before and after the freeze-thaw test, and adhesive strength. Our findings demonstrated that thermal contraction and expansion induced a relatively escalated frequency of defects in the underwater setting for the aluminum mesh, while the steel mesh saw a higher defect incidence in the air environment. Additionally, it was noted that the adhesive strength exhibited a trend towards augmentation as the mesh size dwindled. Collectively, these results suggest that the employment of smaller mesh sizes can foster improved adhesive strength, consequently diminishing tile defects. Further exploration and development of the tile module, informed by these insights, can substantially enhance the efficacy of the construction process.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.469-475
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• 2016

In this work, casting processes, such as filling and solidification, were simulated in order to accurately predict volume shrinkage defects in large-sized sand gravity casting. Turbulent flow of melted materials and a difference of solidification speed can cause volume shrinkage defects. In order to solve this problem and to understand the phenomenon, a porous filter application was studied. Two different porosities of 10 and 20 p.p.i filters were introduced into the gating system, and in view of the results so far achieved, the defect was dramatically reduced by 22%, compared to that without the use of the filter.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.173.2-173.2
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• 2011

대체 에너지 자원 중 폐기물의 소화 가스를 이용한 바이오가스 발전은 이산화탄소에 비해 온실효과 영향력에 21배에 해당하는 메탄가스를 연료로 사용하여 환경부하를 저감시키고 에너지를 생산한다. 바이오가스에 포함된 $H_2S$는 연소 후 $SO_2$형태로 발생되는데 $SO_2$는 수분과 반응을 하게 되면 $H_2SO_4$등의 강한 산성을 띄는 물질로 생성되어 배관 및 발전기에 손상을 주고 저온부식현상을 유발하게 하며, 동물이나 인체에 노출되면 기관지 수축현상이 일어나 호흡기에 영향을 주는 질식성을 띄는 가스이다. 축산바이오가스에 포함된 $H_2S$의 함유량과 가스엔진의 연소 시 배출되는 $SO_2$ 배기가스 성분의 관련성을 검증하기 위해 60-65%의 $CH_4$와 30-35%의 $CO_2$ 성분의 바이오가스를 50kW급 발전기에서 사용하였고 연소 후 배출되는 가스 성분을 분석하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.11-12
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• 2014

In this study, fundamental properties of concrete mixed with fiber has been analysed. Compressive strength, tensile strength and plastic shrinkage has been tested to conduct the optimum addition ratio of fiber. Effect to control press concrete's cracking has been tested. The following results could be made as the conclusion. For the flowability, slump decreased about 41-79% when all types of fiber used in the concrete. When the addition ratio of fiber is 1.2%, the slump of concrete decreased about 45%. For the strength properties. all the specimens with different addition ratio of fiber shown higher compressive strength comparing with Plain. Comparing with Plain, cracking decreased when the fiber added. Especially, when NY fiber used in the concrete, the plastic shrinkage did not occurred. In addition, Latex modified concrete(LMC) has improved superior physical and chemical properties. The properties of latex, combined with the low water-cement ratio, produce a concrete that has improved flexural, tensile, and bond strength, lower modulus of elasticity, increased freeze-thaw resistance, and reduced permeability compared to conventional concrete of similar mix design.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.119-127
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• 2011

Objective of this study is to identify properties on strength increase of hardened concrete and fluidization of non-hardened concrete using waste ceramics generated by construction waste, which is a type of industrial waste, and by ceramics, which is a clay plastic, during its production process, and determine length change ratio caused by drying shrinkage during substitution of recycle aggregate and waste ceramics, and whether they can be used as concrete compounds. Slump of non-hardened concrete exhibited the best fluidization and formability at recycled aggregate's replacement ratio of 60% driven by higher substitution ratio of recycled aggregate and waste ceramics while air content met the KS requirement when substitution ratio of waste ceramics was $4,000cm^2/g$. Compressive strength of hardened concrete exceeded the requirements at early age and standard age and temperature dropped by roughly $6{\sim}10^{\circ}C$ less than the standard at maximum temperature in adiabatic temperature increase, which will hopefully result in stronger durability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.125-133
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• 2011

The requirement for durability of concrete bridge deck is increasing as the deterioration for the concrete bridge deck exposed to severe environment has been increased. For this reason, the concern about high-durable concrete is being high. Recently, a metakaolin is highly spotlighted as new admixture because its strength and durability are equivalent to silica fume. On the other hands, there are few researches for the metakaolin concrete bridge deck in domestic. So many various long-term data on the mechanical property and durability is needed to apply metakaolin concrete at the concrete bridge deck construction field. This study is aim to evaluate the long-term mechanical properties and durability of metakaolin concrete bridge deck with curing age. Mechanical properties are estimated by the compressive and flexural strength, and the drying shrinkage, the chloride resistance, the scaling, and freezing and thawing characteristics are compared with curing age. According to the results, when the metakaolin concrete is used, the development of compressive and flexural strength proceed in both the early and old ages. It is also improved the resistance of chloride penetration, freezing and thawing in concrete. It was showed that replacement of metakaolin was efficient for the reduction of the drying shrinkage.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.853-856
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• 2008

Lightweight foamed concretes are mainly used in apartment building construction for building room floor insulation, sound proof and height difference adjustment, etc. However, existing lightweight foamed concretes have problems like volume reduction by foam removal and excessive crack occurrence, etc, and for compensation, they developed improved concrete binders for lightweight foamed concrete with special characteristics by adding admixture materials used in concrete manufacturing. Therefore, this study reviewed the possibility of its practical use by analyzing all the engineering characteristics after producing imitation member proposed as actual binders and piling lightweight foamed concrete as improved lightweight foamed concrete binder through prior study, the results are as follows. Plain in which various pulverulent materials are mixed showed about 230mm of flow value, satisfying the target flow value, and at 100mm member, about 4mm of settlement occurred, showing a settlement depth reduction effect double the OPC. On strength, OPC showed highest value, but the three levels all showed strengths above the specified value of KS standard 0.5 grade. From the analysis of drying shrinkage member crack, plain, about 0.1mm, was shown very excellent against drying shrinkage crack.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.314-320
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• 2001

In this paper, the properties of an expansive agent (CaO-CaS $O_4$) for dry shrinkage compensation were investigated by a series of experimental program, which might be used at On-Dol heating system as mortar type. The expansion principle of the CaO-CaS $O_4$ was mainly verified. As a result of this study, the correlation between the content of the expansive agent and the compressive strength was obtained in the form of exponential function(Y = A $e^{-x}$), showing that as the content of expansive agent increased as the expansion performance with the compressive strength increased by only a certain amount. Also, as a results of the analysis of a correlation between the expansive performance and the chemical properties which generally accompanied a part of quality management in manufacturing the expensive cement, the expansive performance was relative to only the contents of the F-CaO among chemical properties(Blaine, +44$\mu\textrm{m}$R, F-CaO, S $O_3$,L.O.I). And it was clarified that the results were relative to the second order function, showing that if the contents of the F-CaO increased the expansive performance Increased.d.