• Journal of the Society of Disaster Information
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• v.2 no.1
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• pp.129-137
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• 2006

The present work is attempt to evaluate the temperature dependence of blast furnace slag concrete(BFSC) based on the concrete strength cured with different curing temperatures and ages. A equivalent substitution index(ESI) was induced to explain temperature dependence of concrete quantitatively as well as concrete strength. The results from compressive strength showed substantial crossover effect. which is the phenomenon that the compressive strength cured at low temperature becomes stronger than the one cured at high temperature. The crossover effect found more definitely on BFSC than plain concrete.. The ESI became 1.1 and 1.0 for the BFSC cured at $20^{\circ}C$ and $30^{\circ}C$ after age of 56 days, respectively. Which means that the contribution to strength development of blast furnace slag per unit mass is stronger than that of the Portland cement. It was considered therefore that the optimum curing temperature for BFSC is $20^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.148-153
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• 1996

Concrete with ground granulated blast-furnace slag can be affected by frost attack because the reaction of hydration is slow at the early age. In this study, therefore, the freezing and thawing test has been carried out to investigate the freezing and thawing resistance on concrete with ground granulated blast-furnace slag. The freezing and thawing test has been performed on concrete a blended cement, which was substituted by ground granulated blast-furnace slag with 4 kinds of ratio (non-admixture, 20%, 40% and 60%). And also tested on concrete added the AE agents to the concrete of same mix proportion to search the improvement effects about the resistance. As a result, the freezing and thawing resistance showed a tendency of reduction in proportion to the increase of the substitution ratio. For non-AE concrete, resistances of the freezing and thawing were very poor as the durability index indicated less than 5.8%. For AE concrte, resistance of the freezing and thawing were excellent as the durability index indicated more than 80.9%.

• Journal of Soil and Groundwater Environment
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• v.21 no.2
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• pp.1-7
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• 2016

Ferrous slag is a by-product from steel making process and waste concrete is generated from construction activities. Large part of ferrous slag and waste concrete are recycled as construction materials. However, Ca²⁺ leaching out of ferrous slag and waste concrete in the water-contacting environment can cause a strength change. Strength can be reduced due to the dissolution of solid form of CaO which is one of the main contents of ferrous slag and waste concrete. On the other hand, strength can be enhanced due to the pozzolanic reaction of cementitious components with water. In this study, steelmaking slag, blast furnace slag, and waste concrete were aged by exposure to raining events, and the change of their compaction and shear strength characteristics was investigated. Optimum moisture content of all materials used in this study increased with aging period while maximum dry unit weight slightly decreased, implying that the relative contents of fine particles increased as the CaO solid particles were dissolved. Internal friction angle and shear strength of recycled materials also increased with aging period, indicating that the materials became denser by the decrease of void ratio attributed to the fine particles generated during the weathering process and the development of cementitious compounds increasing the bonding and interlocking forces between the particles. The results of this study demonstrated that mechanical strength of recycled materials used as construction materials has little chance to be deteriorated during their service life.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.1035-1040
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• 2001

The effects of polymer-binder ratio and slag content on the properties of combined wet/dry-cured polymer-modified mortars using granulated blast-furnace slag (slag) are examined. As a result, the flexural and compressive strengths of polymer-modified mortar using slag reaches a maximum at a slag content of 40%, and is inclined to increase with increasing polymer-binder ratio. The water absorption, carbonation depth and chloride ion penetration depth tend to decrease with increasing polymer-binder ratio and slag content.

• Advances in concrete construction
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• v.11 no.2
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• pp.99-109
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• 2021

Slag blended concrete is widely used as a mineral admixture in the modern concrete industry. This study shows an optimization process that determines the optimal mixture of air-entrained slag blended concrete considering carbonation durability, frost durability, CO2 emission, and materials cost. First, the aim of optimization is set as total cost, which equals material cost plus CO2 emission cost. The constraints of optimization consist of strength, workability, carbonation durability with climate change, frost durability, range of components and component ratio, and absolute volume. A genetic algorithm is used to determine optimal mixtures considering aim function and various constraints. Second, mixture design examples are shown considering four different cases, namely, mixtures without considering carbonation (Case 1), mixtures considering carbonation (Case 2), mixtures considering carbonation coupled with climate change (Case 3), and mixtures of high strength concrete (Case 4). The results show that the carbonization is the controlling factor of the mixture design of the concrete with ordinary strength (the designed strength is 30MPa). To meet the challenge of climate change, stronger concrete must be used. For high-strength slag blended concrete (design strength is 55MPa), strength is the control factor of mixture design.

• Resources Recycling
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• v.17 no.5
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• pp.11-18
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• 2008

The purpose of this study was to evaluate the effects of blast-furnace slag on chemical attack and carbonation of latex-modified concrete (LMC) and ordinary portland cement concrete as slag contents. Main experimental variables were performed latex contents (0%, 15%) and slag contents (0%, 30%, 50%). The compressive strengths, chemical attacks resistance and carbonation depth were measured to analyze the characteristic of the developed LMC and BS-LMC(latex-modified concrete added blast-furnace slag) on hardened concrete. The test results showed that compressive strength of BS-LMC with blast-furnace slag content 30% was quite similar to it of OPC without slag content. The structural quality deterioration was concerned when blast slag content was up to 50%. However, carbonation restraint of BS-LMC with blast-furnace slag 30% was bigger then that of opc. Also, the effects of added latex on OPC and BS-LMC were increased on the carbonation restraint and chemical attacks resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.911-914
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• 2000

Surface glossing and physical properties of exposed concrete varied with blast furnace slag content are dsicussed in this paper. According to experimental results, as the content of blast furnace slag increases, concrete gains high strength moderately at later stage and surface glossing increase. It shows that glossing decrease with age. Surface glossing shows high as W/B decreases and surface coating is applied. Concrete according to form type shows good results in surface glossing in order for acryl form, fancy form and steel form.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.124-128
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• 1997

In order tohave a betterunderstanding of thefavorable effect ofground granulated blast-furnace slag and fly ash, slump loss, temperature risingand compressive strength of concrete were investigated into diffrent conditions. When slag was mixed with ordinary portland cement as30%, slump loss gotto some 18% at 60min, maximum temperatureto some $43^{\cire}C$ at 180min, compressive strength similar to that of ordinary portland concrete at 28 days. Therefore it wasnoted thatslump loss andmaximum teaperaturerising of concrete were very reduced according to ground granulated blast-furnace slag and fly ash mixed with ordinary portland cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.217-218
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• 2011

The advantages of blast-furnace slag concrete may include lower hydration heating velocity, restraint on concrete temperature increase, long-age strength improvement due to latent hydraulic reaction, improved water tightness, and repulsion to chemical erosion. These advantages contribute to the high quality of the blast-furnace slag concrete. However, the blast-furnace slag concrete has its limitations as well. These disadvantages may include retarded setting and elongated retention of mold due to the weak strength of early-age. Nevertheless, much research is currently under way to improve the aforementioned issues. To improve activity of blast furnace slag powder, alkaline irritants has been used. In this study, we analyze effect on activity fineness and rate of substitution of Alkali Activator toward activity.

• Computers and Concrete
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• v.16 no.3
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• pp.487-502
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• 2015

This study investigated particle expansion in basic oxygen furnace slag (BOF) and desulfurization slag (DSS) after heat curing by using the volume method. Concrete hydration was accelerated by heat curing. The compressive strength, ultrasonic pulse velocity, and resistivity of the concrete were analyzed. Maximum expansion occurred in the BOF and DSS samples containing 0.30-0.60 mm and 0.60-1.18 mm particles, respectively. Deterioration was more severe in the BOF samples. In the slag aggregates for the complete replacement of fine aggregate, severe fractures occurred in both the BOF and DSS samples. Scanning electron microscopy revealed excess CH after curing, which caused peripheral hydration products to become extruded, resulting in fracture.