• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.665-668
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• 2008

Recently the city construction and the concrete structures are more becoming extra weight and the efficient use of the space by the population intensively and follow in industrial intensive commerce and the residence commerce composition building which leads the high story of the building. Consequently the high rise of the building which space applies efficiently in objective which will increase continuously. Also with high rise of buildings durability it will be able to increase the life of the structure is emphasized and the concrete structure is demanding the more high strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.9-18
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• 2016

The thermal and mechanical properties of fiber-reinforced cement-based composite for solar thermal energy storage were investigated in this paper. The effect of the addition of different cement-based materials to Ordinary Portland cement on the thermal and mechanical characteristics of fiber-reinforced composite was investigated. Experiments were performed to measure mechanical properties including compressive strength before and after thermal cycling and split tensile strength, and to measure thermal properties including thermal conductivity and specific heat. Test results showed that the residual compressive strength of mixtures with OPC and slag was greatest among cement-based composite. Thermal conductivity of mixtures including graphite was greater than that of any other mixtures, indicating favor of graphite for improving thermal transfer in terms of charging and discharging in thermal energy storage system. The addition of CSA or zirconium increased specific heat of fiber-reinforced cement-based composite. Test results of this study could be actually used for the design of thermal energy storage system in concentrating solar power plants.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.111-119
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• 2023

Recently, a variety of new cement-based materials have been developed, and attempts to predict the properties of these new materials are increasing. In this study, we aimed to predict the rheological properties of binary blended pastes. The cementitious materials used in the study included Portland cement (PC), fly ash (FA), blast furnace slag (BS), and silica fume (SF). The three binder components, fly ash, blast furnace slag, and silica fume, were blended with cement as the foundational composition. We predicted the yield stress and plastic viscosity of the pastes using the YODEL (Yield stress mODEL) and Krieger-Dougherty's equation. The predictive model's performance was validated by comparing it with experimental results obtained using a rheometer. When the rheological properties of the binary blended paste were predicted by reconstructing the properties and parameters used to predict the individual materials, it was evident that the predictions made using the proposed method closely matched the experimental results.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.593-600
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• 2016

The paper presented investigates the effects of kaolinite on strength properties of alkali-activated multi-component cement. The binders of this study was blended of ground granulated blast furnace slag (GGBFS), fly ash (FA), silica fume (SF) and kaolinite (KA). In this study, the specimens of combination of 20%~70% GGBFS, 10%~60% FA, 10% SF (constant ratio) and 10%~50% KA binder were used for strength properties tests. The water/binder ratio was 0.5. The binders (GGBFS + FA + SF + KA) was activated by sodium hydroxide (NaOH) and sodium silicate ($Na_2SiO_3$) was 10% by total binder weight (10% NaOH + 10% $Na_2SiO_3$). The research carried out is on the compressive strength, water absorption, ultrasonic pulse velocity (UPV) and X-ray diffraction (XRD). The compressive strength decreased as the contents of KA increase. One of the major reason for this is the low reactivity of KA compared with other raw materials used as precursors such as GGBFS or FA. The presence of remaining KA indicates that the initially used quantity has not fully reacted during hydration. Moreover, the results have indicated that increased of KA contents decreased UPV under all experimental conditions. The drying shrinkage and water absorption increased as the content of KA increase. Test result clearly showed that the strength development of multi-component blended cement were significantly dependent on the content of KA and GGBFS.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.533-536
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• 2008

Recently, in Korea, there has been an increasing number of research papers published which are to improve durability of concrete, particularly by analyzing correlation between diffusivity of chloride and porosity/pore size distribution. In these studies, such test methods as mercury intrusion porosimetry(MIP), gas adsorption or image analysis method are used to analyze the microstructure of materials while MIP is most widely used for concrete. This study analyzes the results of porosity and pore size distribution of paste and concrete adding fly ash or blast furnace slag by using MIP equipment which is widely used for determining micro-porosity structure of cementitious materials. A variation in porosity and pore size distribution at the curing day 3, 7 and 28 has been observed by using MIP equipment for cement paste 35%, 40%, 45%, 50%, 55%, 60% of W/C when using $300kg/m^3$ of cement, 35%, 45%, 55% of W/C when replaced 60% with blast-furnace slag, and 35%, 45%, 55% of W/C when replaced 30% with fly ash. For long-term water cured normal OPC concrete and mixed concrete replaced 60% with blast-furnace slag powder, micro-structure of the sample has been analyzed by using MIP equipment when W/C indicated 40%, 45%, 50% respectively and the binder varied $300kg/m^3$, $350kg/m^3$, $400kg/m^3$, and $450kg/m^3$.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.64-69
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• 2018

The purpose of this study is to expand the use of coal ash and coal slag in thermal power plants. In addition, controlled low strength materials was developed to prevent mine settlement. Bottom ash and KR slag are mixed at ratio of 7:3 to expand the use of industrial by-products through carbonate reaction and inhibit the exudation of heavy metals. In order to efficiently fill the abandon mine, workability and physical properties were evaluated according to flow. As a result of elution of harmful substance experiment, it was confirmed that the carbonation reaction inhibited the elution of heavy metals. It was confirmed that the difference in water ratio was the difference in specific surface area of the controlled low strength materials. It was confirmed that the working efficiency is excellent when the flowability is 300mm compared to 260mm. compressive strength measurement result was relatively high at 260mm compared to 300mm because the number of pores due to decrease of water ratio was small.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.94-101
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• 2011

In this study, in order to develop organic-inorganic hybrid packaging materials(PM) of bike paths using blast furnace slag(BS) as industrial by-products, fundamental properties of organic-inorganic hybrid packaging materials were performed. Test result, the increase of Acryl emulsion polymer(AEP)/binder(B) ratios tends to delay the setting time, to increase the table flow, to decrease the strength by material segregation and to increase the length change. The optimal mix proportion of AEP decides on 40%(AEP/B) due to workability and high strength. The increase of BS replacement ratios also tends to delay the setting time, to separate AEP from B and to decrease the strength by material segregation. When BS replacement ratios were lower than 40%, they are satisfied with goal properties.

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.9-16
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• 2015

The goal of this research was evaluating and suggesting the solution of preventing carbonation of concrete replaced high-volume of slag. The concrete mixtures were prepared with high-volume slag and recycled aggregate, and the concrete samples were evaluated the carbonation depth with various surface treatment methods. For various surface treatment methods and surface protecting sheets, bonding strength and carbonation depth were measured. Basically, from the results, the carbonation of concrete was completely prevented with any type of surface treatment method and surface protecting sheet as far as the surface treatment materials were remained. Therefore, in this research, it was known and suggested that the easiness of handling and sufficient bonding performance was much important than the quality of surface protecting sheets.

• Journal of the Korea Institute of Building Construction
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• v.15 no.5
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• pp.457-464
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• 2015

The alternative material for cement has been attracting attention in construction projects. Especially, the alkali activated slag(hereafter, AAS) concrete is able to use for a structural vertical member because of 40MPa of compressive strength, However, the research about time-dependent deformation such as creep which is important to strength member is insufficient. Therefore, in this study, experiments were performed with respect to time-dependent deformation including the drying shrinkage and creep deformation of AAS concrete. The creep deformed ratio of AAS concrete was more than OPC concrete by approximately 4.3% and the dry shrinkage deformation of AAS concrete was more than OPC concrete by approximately 69%. The large amount of sodium silicate, alkali activator, is added causing temperature crack than promoted drying and drying creep which is confirmed by water ration test and SEM.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.87-95
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• 2012

This study investigated the compressive strength, flexural strength, setting time, and rebound when blast furnace slag and anhydrite, which are widely used mineral admixtures for concrete, are applied to shotcrete. When Ordinary Portland Cement (OPC) was replaced at a rate of 10% with blast furnace slag and anhydrite, the initial and final setting time requirements were all satisfied. However, when OPC was replaced at a rate of 20%, final setting was delayed, revealing that this mixture was not suitable for shotcrete. Compressive strength test results showed that the mixture with 10% OPC replacement rate met the target strength at 1 day and 28 days for permanent tunnel support usage. Particularly, the mixture designed with OPC replacement by blast furnace slag and anhydrite at rates of 5% showed the highest compressive strength. Rebound measurements revealed that this mixture exhibited excellent performance with 23% reduction in the rebound compared to the shotcrete that was produced with only OPC binder.