• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.642-649
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• 2021

Energy saving standard for buildings are strengthened, the application of exterior insulation finishing system and thickness of insulation materials are increasing. Most buildings with exterior insulation finishing system is applied organic insulating material. Organic insulating material have workability, economic feasibility, reduction in construction cost, and excellent thermal insulation performance. However, Organic insulating material is very vulnerable to heat, so when a fire occurs, rapid fire spread and toxic gas are generated, causing many casualties. Inorganic insulating material can be non-combustible performance, but it is heavy and has low thermal insulation performance. Mineral wool has higher thermal insulation performance than other types of inorganic insulating material, but mineral wool is disadvantageous to workability and vulnerable to moisture. Glass bubble are highly resistant to water and chemically stable substances. In addition, the density of the glass bubble is very low and the particles are spherical, fluidity is improved by the ball bearing effect. Glass bubbles can be used with cement-based ino rganic insulating material to impro ve the weight and thermal insulatio n perfo rmance o f cement-based inorganic insulation. This study produced a inorganic insulating materials were manufactured using cement-based materials and glass bubble. In order to evaluate the insulation performance and flame retardant performance of cement-based super light-weight inorganic insulating materials using with glass bubble, insulation performance or flame retardant and non-combustible performance were evaluated after manufacturing insulating materials using micro cement and two types of glass bubbles. From the test result, Increasing the mixing ratio of glass bubbles improved the insulation performance of cement-based super light-weight inorganic insulating materials, and when the mixing ratio of glass bubbles was 10%, it sho wed sufficient flame retardant and no n-co mbustible perfo rmance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.116-122
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• 2019

This study evaluated the properties of Coal gasification slag(CGS) according to the CGS contents of cement mortar condition as a basic step to examine the applicability of CGS as concrete fine aggregate. Flow increased with increasing CGS contents for both Crushed sand a(CSa) and Crushed sand b+Sea sand(CSb+SS), but the amount of air contents decreased to the opposite tendency. Based on 28 days is maximum compressive strength was obtained at CGS 50% when CSa was used and CGS 75% when CSb+SS. The flexural strength were the maximum at 25% and 50% of CGS, but the tendency was similar to the compressive strength. Compared with CSa, the compressive strength and flexural strength 5% higher than those of CSb+SS, in CGS using of were about 5% higher than those of unused CGS. As a result of comprehensive study on the quality of mortar according to the CGS contents, it can be concluded that when CGS is mixed with fine aggregate at about 50%, it can contribute to securing workability and strength development positively so that resource recycling and quality improvement can be achieved at the same time.

• Journal of the Korea Institute of Construction Safety
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• v.6 no.1
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• pp.12-18
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• 2024

High-rise, large-scale, and diversification of buildings are possible, and the reduction of concrete cross-sections reduces the weight of the structure, thereby increasing or decreasing the height of the floor, securing a large number of floors at the same height, securing a large effective space, and reducing the amount of materials, rebar, and concrete used for designating the foundation floor. In terms of site construction and quality, a low water binder ratio can reduce the occurrence of dry shrinkage and minimize bleeding on the concrete surface. It has the advantage of securing self-fulfilling properties by improving fluidity by using high-performance sensitizers, making it easier to construct the site, and shortening the mold removal period by expressing early strength of concrete. In particular, with the rapid development of concrete-related construction technology in recent years, the application of ultra-high-strength concrete with a design standard strength of 100 MPa or higher is expanding in high-rise buildings. However, although high-rise buildings with more than 120 stories have recently been ordered or scheduled in Korea, the research results of developing ultra-high-strength concrete with more than 130 MPa class considering field applicability and testing and evaluating the actual applicability in the field are insufficient. In this study, in order to confirm the applicability of ultra-high-strength concrete in the field, a preliminary experiment for the member of a reduced simulation was conducted to find the optimal mixing ratio studied through various indoor basic experiments. After that, 130 MPa-class ultra-high-strength concrete was produced in a ready-mixed concrete factory in a mock member similar to the life size, and the flow characteristics, strength characteristics, and hydration heat of concrete were experimentally studied through on-site pump pressing.

• Journal of the Society of Disaster Information
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• v.7 no.4
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• pp.286-293
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• 2011

Accordingly architectural structure is getting high-rise and bigger, a use of high strength and high performance concrete has been increased. High performance concrete has cons of explosion in a fire. This explosion in the fire can cause the loss of the sheath on a concrete surface, therefore it effects that increasing a rate of heat transmission between the steel bar and inner concrete. Preventing this explosion of high performance concrete in the fire, many kinds of researches are now in progressing. Typically, researches with using polypropylene-fiber and steel-fiber can prove controling the explosion, but the reduction of mobility was posed as a problem of workability. Consequently, to solve the problem as mentioned above, concrete cans secure fire resisting capacity through the using of coating liquid, including Ester-lubricant and non-ionic characteristic surfactant. This research has been drawn a ideal condition in compressive strength areas of concrete by an experiment. When applying 13mm of polyamide fiber, proper fiber mixing volume by compressive strength areas of concrete more than 2.5kg in 160MPa. These amount of a compound can control the explosion.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.356-362
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• 2016

Light-weight concrete uses forming agents for reducing weight and high heat insulation property. However, the forming agents make problems of decreased volume and compressive strength of the concrete. This research aims to having weight-reduction and securing heat insulation property using recycled wasted form polyurethane without any forming agents. A small quantity of admixture used for constructability and avoiding material segregation. We picked admixtures from two different companies which shows evenly dispersed of wasted form polyurethane. This research conducts a study on the effect of mixing ratio of admixture on the light-weight concrete used wasted form polyurethane. As a result of the test, increased mixing ratio of the admixtures results reduced fluidity of concrete. On the other hand, percentage of moisture content and compressive strength are increased slightly. Combustibility performance and sound insulation performance are also secured, as well.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.151-161
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• 1996

Recently, polypropylene fiber reinforced mortar and concrete as civil and architectural materials have been used in major countries in the world. Polypropylene fiber reinforced concrete has many advantages in terms of economical aspect, chemical stability and durability. It has been reported that polypropylene fiber can control restrained tensile stresses and cracks and increase toughness, resistance to impact, corrosion, fatigue and durability. The purpose of the present study is, therefore, to investigate the strength as well as many mechanical characteristics including toughness and shrinkage control properties. A specially devjsed shrinkage test has been applied to measure the crack control characteristics of polypropylene fiber reinforced concrete. The present study indicates that the polypropylene fiber reinforced concrete curbs greatly the crack occurrence due to shrinkage and enhances toughness resistance. The present study provides a firm base for the efficient use of polypropylene fiber reinforced concrete in actual construction such as pavements and slab structures.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.175-183
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• 2008

Domestically, application of High Flowing Self-Compacting Concrete (HSCC) is limited to building structures and it is difficult to find examples of application in civil infrastructural constructions. However, in the case of North America and Europe, by introducing precast and prestressed system, HSCC is being used for high-density reinforced bridge members. Hence it is assessed that broadening the utilization of HSCC into areas such as bridges and civil construction is required. Therefore in this research, to apply HSCC to high-density reinforced bridge members, ground granulated blast-furnace slag and fly ash were mixed in binary and ternary systems. Also the dynamical characteristics of HSCC, following 1st class regulations of Japan Society of Civil Engineers (JSCE), were assessed to enable application on high-density reinforced structures. The test results revealed ternary system mixture showed better mechanical characteristics than binary system mixture and the application on high-density reinforced precast bridge members seems possible.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.177-184
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• 2021

In this study, the effects of ground granulated blast furnace slag(GGBFS) and expansive additive(EA) on early strength mortar were examined for the purpose of reducing carbon and improving cement performance. As a result, ealry strength Portland cement(EPC) tended to decrease in flow compared to ordinary Portland cement(OPC), but binder with EPC and GGBFS was possible to obtain higher liquidity than OPC. EPC showed higher compressive strength and shrinkage than OPC. The compressive strength of specimen with EPC and GGBFS was reduced proportionally to the replacement ratio of GGBFS. The replacement ratio of GGBFS above the compressive strength equivalent to OPC was higher under low temperature conditions. The use of GGBFS resulted in high shrinkage compared to OPC, and this characteristic was even greater under low temperature conditions. The shrinkage of specimen with EA was decreased in early ages, but was higher than the OPC in long-term ages.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.135-140
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• 2021

In this study, the concrete aggregate shape features were extracted from the cross-section of a normal concrete strength cylinder, and the compressive strength of the cylinder was predicted using artificial neural networks and image processing technology. The distance-angle features of aggregates, along with general aggregate shape features such as area, perimeter, major/minor axis lengths, etc., were numerically expressed and utilized for the compressive strength prediction. The results showed that compressive strength can be predicted using only the aggregate shape features of the cross-section without using major variables. The artificial neural network algorithm was able to predict concrete compressive strength within a range of 4.43% relative error between the predicted strength and test results. This experimental study indicates that various material properties such as rheology, and tensile strength of concrete can be predicted by utilizing aggregate shape features.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.17-24
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• 2024

The characteristics of low-heat concrete, mixed with ground blast furnace slag and ferronickel slag aggregate, were analyzed. Moreover, the applicability of this concrete for mass concrete in LNG storage tanks was examined. Initially, the study investigated the characteristics of fresh and hardened concrete. Subsequently, the temperature rising curve was obtained. Utilizing the obtained parameters from the curves, a series of thermal stress analyses for the LNG storage tank were conducted to assess the risk of cracking. The results confirmed that concrete mixtures incorporating ground blast furnace slag and ferronickel slag aggregate not only exhibited sufficient workability but also achieved a compressive strength of approximately 40 MPa within 28 days. Furthermore, the concrete demonstrated a lower terminal heat rise and a faster heat generation rate compared to low-heat Portland cement concrete. An analysis of thermal stress in various sections of the LNG tank validated a low risk of cracking.