• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.35-41
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• 2013

In this study, we investigated the strength development and durability of geopolymer mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless geopolymer concrete. In order to compare with the geopolymer mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to freezing-thawing of the geopolymer mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, and improve the resistance of freezing-thawing of approximately 20%, but promote the velocity of carbonation of 2.2~3.5 times.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.679-683
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• 2016

Boilers of large-sized coal-fired power plants are being operated under very poor conditions such as continuous operation or repeating of start-up and shutdown for a stable supply of electricity. Thus periodic inspection and maintenance are required to ensure reliability of operation. The loads of existing scaffolding systems for the maintenance of boilers are concentrated in the lower parts structurally, which may cause a serial collapse of the overall scaffolding system when there are problems in some members. Therefore, in this study, a safe furnace scaffolding system is developed by dispersing the loads in the upper part, as well as minimizing the hazards of serial collapsing. In addition, for cases where the direct installation of furnace scaffolding is challenging owing to the structure of the boiler tube, a lifting system for the installation of furnace scaffolding is developed so that furnace scaffolding can be supported to secure the integrity of the power generating facility.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.40-48
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• 2012

This study evaluates the shear performance of reinforced concrete beams with electric arc furnace oxidizing slag aggregates generated from iron manufacture. A total of six simple supported specimens were cast and tested in shear. The main test variables were the type of aggregates and the amount of shear reinforcements. The specimens under four point loading had a shear span-to-depth ratio of 2.5 and a rectangular section with a width of 200mm and an effective depth of 300mm. Existing equations to predict the shear strength of the specimens were used in this study. Furthermore, a finite element analysis using shear analytical model was performed to trace the shear behavior of the specimens with electric arc furnace oxidizing aggregates. From the test results, the shear performance of specimens with electric arc furnace oxidizing aggregates is similar to that of specimens with natural aggregates.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.82-89
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• 2014

This study evaluates the shear performance of precast beams with ground granulated blast furnace slag. A total of four specimens according to replacement ratio of ground granulated blast furnace slag. The specimens under three loading points had a shear span-to-depth ratio of 2.5, and a rectangular section with a width of 200mm and a effect depth of 300 mm. In this study, existing equations were used for predicting the shear strength of the specimens. The shear strength by existing equations was compared with those of 89 reinforced concrete beams without shear reinforcement. It can be shown from experimental results that all specimens with ground granulated blast furnace slag showed a similar shear strength as compared with the specimen with portland cements alone.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.9-12
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• 2013

The pavement is generally used on the highways, local loads, roads for bicycle riding and neighborhood living facility such as parking lot, plaza, park and sports facilities. However, the pavement material that is usually used on the most of roads is impermeable asphalt-concrete and cement-concrete. If the pavement material is impermeable, many problems can be happened on the drainage facilities in the rainy season. Additionally, a lot of rainwater on the pavement surface cannot permeate to the underground and flows to the sewage ditch, stream and river, etc. If a lot of rainwater flows at once, the floods can be out along the streams and rivers. So, underground water can be exhausted. Micro organisms cannot live in the underground. Recently, many studies has been conducted to exploit the permeable concrete that has high performance permeability. However, it is required to develop the permeable concrete which has high strength and durability. In this study, permeable and strength tests were performed to investigate the permeable characteristics of porous concrete according to fine aggregate content and substitution ratio of blast furnace slag. In this test, crushed stones with 10~20 mm and sand with 5~10 mm were used as a coarse aggregate and a fine aggregate respectively. The substitution ratio of blast furnace slag to cement weight is 0 %, 15 %, and 30 %. The ratio of fine aggregate to total aggregate is 0 %, 18 %, and 35 %. As a result, permeability coefficient was decreased according to fine aggregate ratio of total aggregate. Compressive strength was also decreased according to substitution ratio of blast furnace slag.

• Land and Housing Review
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• v.3 no.3
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• pp.287-297
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• 2012

To develop 80MPa-high strength concrete with ternary cement used in OPC, blast-furnance slag, and fly ash, mixing ratio of blast-furnace slag and fly ash was evaluated in material characteristics before and after hardening of the high strength concrete. According to the evaluated results of material characteristics before and after hardening of the high strength concrete, the flowability and long-term compressive strength increase up to 30% mixing ratio of blast-furnace slag and fly ash. Also, it is superior to characteristics of length change and neutralization due to the use of mineral admixture when compared in test sample mixed with OPC. The evaluated results show that material characteristics of the high strength concrete was the most outstanding performance at blast-furnace slag of 25% and fly ash of 15%. The result of this study will be useful for the development of high strength concrete as a substitute of costly silica fume in the near future.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.669-672
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• 2008

To analyze possibility for high performance concrete that massively displaces blast furnace slag, this study analyzed the characteristics of concrete by blast furnace slag displacement rate changes, and the results are summarized as follows. Firstly, as for fresh concrete characteristics, flow tended to increase and air amount decreased with increase in blast furnace slag displacement rate, and settling time was shown delayed. As for hardened concrete characteristics, in conditions where blast furnace slag displacement rate increased up to 50%, the compressive strength decreased below OPC at early age, however at age 28 days, its level was no less than that of OPC, and as for temperature rise by simple insulation, it decreased as displacement rate increased at early stage of hydration, but in the latter stage, hydration progress slowed down and hydration heat increased.

• Journal of the Korea Institute of Building Construction
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• v.9 no.2
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• pp.77-83
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• 2009

In this study, a test has been carried out to solve the problem with ground granulated blast-furnace slag, low early strength & lack of supply and to find out a way to use as concrete admixture of the ultrafine blaine air cooling slag which is all disposed as the by product of air cooling slag and its test was conducted to the replacement rate of ultrafine blaine air cooling slag & mixing condition of every concrete admixtures by type for the purpose of obtaining later a basic data for practical use of the cement that used ultrafine blaine air cooling slag by conducting comparative analysis. If ultrafine-blaine air cooling slag is used to the concrete following the results, a high efficiency water reducing agent won't be needed much for flow acquisition due to a high increase in flow, and the stripping time of concrete form will be shortened thanks to the acquisition of early strength, And though, it has the problems with long term strength which is similar or a little lower than the 3 types of ground granulated blast-furnace slag, it's still applicable as the substitute materials for 3 types of ground granulated blast-furnace slag at 10, 15% replacement rate of ultrafine-blaine air cooling slag, at which it shows higher activation index than 3 types of ground granulated blast-furnace slag.

• Plant Journal
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• v.13 no.3
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• pp.36-46
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• 2017

In the reaction furnace of modified Claus process, chemical equilibrium reactions and kinetic reactions occur simultaneously. The main kinetic components are hydrogen ($H_2$), carbon monoxide (CO), carbonyl sulphide (COS) and carbon disulphide ($CS_2$). The equilibrium calculations, empirical correlations and sulfur recovery technology providers' (licensors) data for kinetic components (COS and $CS_2$) in the reaction furnace were analyzed to evaluate the amount of kinetic components by applying them to five different projects in which GS Engineering & Construction participated. Kinetic components ($H_2$ and CO) are also calculated and the results are analyzed to evaluate the impact of temperature in the reaction furnace and the waste heat boiler. Total required $O_2$ deviations for combustion in the reaction furnace are additionally shown, with and without side reactions. A full understanding of side reactions in the modified Claus process can help to improve sulfur recovery efficiency and optimize equipment design.

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.351-359
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• 2013

Blast furnace slag (BFS) have many advantages that are related to effective value improvement on applying to concrete while side effects of blast furnace slag also appear. Thus, research team conducted an experiment with high volume slag to see if the attribute of waste alkali accelerator for mixing rate, mixed use of NaOH and $Na_2SiO_3$, and early strength agent for mixing rate for replacement ratio and for the types of the stimulants in order to increase the use of blast furnace slag1s powder. As the result of the experiment, when it comes to compression strength, all of the alkali stimulants have been improved as the replacement rate increases except for sodium hydroxide. Among the alkali stimulants, sodium silicate was high on dynamic elastic modulus and absorption factor. In case of early strength agent, the mix of mixing 1.5% and blast furnace slag 75% have showed high strength enhancement. In event of Waste Alkali accelerator, it has showed different consequences for each experiment.