• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.52-58
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• 2017

Concrete made with ground granulated blast-furnace slag(GGBS) has many advantage, including improved durability, workability and economic benefits. GGBS concrete is that its strength development is considerably slower under standard $20^{\circ}C$ curing conditions than that of portland cement concrete, although the ultimate strength is higher for same water-binder ratio. GGBS is not therefore used in application where high early age strength is required. In this study, to overcome the limitation of the initial strength decrease due to the use of slag, the slag substitution rate was changed to 30% under the low temperature curing temperature condition and the slag used concrete composition with the same or higher strength performance as OPC(Ordinary Portland Cement).

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.67-74
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• 2015

In this study, effects of micropores on the freezing-thawing resistance of high volume slag concrete are reviewed. Concrete was made with slag which contains the ground granulated blast furnace slag(GGBS) and the pig iron preliminary treatment slag(PS) by replacing 0, 40, 70 %, then compressive strength, freezing-thawing resistance, micropores were reviewed. Also, specified design strength, target air contents were set. Deterioration was induced by using 14-day-age specimen which has low compressive strength for evaluating deterioration by freeze-thawing action. As results of the experiment, despite of specified design strength which has been set similarly and ensured target air contents, the pore size distribution of the concrete showed different results. Micropores in GGBS70 specimen have small amount of water which is likely to freeze because there is small amount of pore volume of 10~100 nm size at 0 cycle which has not been influenced by freezing-thawing. For these reasons, it was confirmed that the freezing-thawing resistance performance of GGBS70 is significantly superior than other specimens because relatively small expansion pressure is generated compared to the other specimens.

• Corrosion Science and Technology
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• v.8 no.5
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• pp.171-176
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• 2009

The chloride threshold level (CTL) in mixed concrete containing, ordinary Portland cement (OPC), pulverized fuel ash (PFA) ground granulated blast furnace slag (GGBS), and silica fume (SF) is important for study on corrosion of reinforced concrete structures. The CTL is defined as a critical content of chloride at the steel depth of the steel which causes the breakdown of the passive film. The criterion of the CTL represented by total chloride content has been used due to convenience and practicality. In order to demonstrate a relationship between the CTL by total chloride content and the CTL by free chloride content, corrosion test and chloride binding capacity test were carried out. In corrosion test, Mortar specimens were cast using OPC, PFA, GGBS and SF, chlorides were admixed ranging 0.0, 0.2, 0.4, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder. All specimens were cured 28 days, and then the corrosion rate was measured by the Tafel's extrapolation method. In chloride binding capacity, paste specimens were casting using OPC, PFA, GGBS and SF, chlorides were admixed ranging 0.1, 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binders. At 28days, solution mixed with the powder of ground specimens was used to measure binding capacity. All specimens of both experiments were wrapped in polythene film to avoid leaching out of chloride and hydroxyl ions. As a result, the CTL by total chloride content ranged from 0.36-1.44% by weight of binders and the CTL by free chloride content ranged from 0.14-0.96%. Accordingly, the difference was ranging, from 0.22 to 0.48% by weight of binder. The order of difference for binder is OPC > 10% SF > 30% PFA > 60% GGBS.

• Computers and Concrete
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• v.31 no.6
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• pp.545-559
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• 2023

In this study, an experimental investigation was conducted to assess the influence of ground granulated blast furnace slag (GGBS) and silica fume (SF) on the fresh and hardened properties of grout specimens and preplaced aggregate concrete (PAC). Grout proportions were optimized statistically using a factorial design and were applied to 10 mm and 20 mm coarse aggregates to produce PAC. The results demonstrate that GGBS has a more significant effect on the compressive strength of grout compared to SF, with a small increase or decrease in the GGBS content having a greater influence on the compressive strength of grout than SF. The water to binder ratio had the most significant effect on the compressive strength of PAC, followed by the coarse aggregate size and sand to binder ratio. An empirical relationship to predict the compressive strength of PAC was proposed through an experimentally derived factorial design along with a statistical analysis of collectively obtained data and a deep literature review. The results predicted by the empirical relationship were in good agreement with those of PAC produced for verification.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.45-52
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• 2017

This study evaluated the durability of nuclear power plant concrete. The main parameters were the water-to-binder ratio and admixture type. The results revealed that high-volume ground granulated blast-furnace slag(GGBS) concrete had lower initial strength, while the strength reached higher after 28 days. On the other hand, the initial strength of fly ash blended concrete was high, but the long-term strength of the robbery was low. The measured durability of GGBS blended concrete was found to be better than that of the existing concrete mix for use in the construction of nuclear power plants. Especially, the GGBS blended concrete was more durable than the fly ash blended concrete in terms of chloride attack, carbonation resistivity and freezing-thawing durability in low compressive strength. The effects of concrete compressive strength according to gamma rays were minor.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.129-130
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• 2014

In the case of concrete structures which have been recently exposed to the marine environment, durability is greatly reduced by the freezing-thawing action. When it is used by appropriately replacing the ground granulated blast-furnace slag(GGBS) that is a industrial by-product, the concrete structure of marine environment is known to have a durability to freezing-thawing resistance. In this experiment, micropore in accordance with a replacement ratio of GGBS was confirmed to show different results respectively. The freeze-thaw resistance was showed different aspects respectively because it is different the amount of water in the pore due to the difference of micropore. Therefore, in this study, the freezing-thawing resistance of sea water by variation of micropores of slag concrete had been evaluated.

• Computers and Concrete
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• v.2 no.1
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• pp.19-30
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• 2005

We study the kinetics of absorption of water in Portland cement concretes added with 60, 70 and 80% of granulated blast furnace slag (GGBS) cured in water and at open air and preheated at 50 and $100^{\circ}C$. A mathematical model is presented that allows describing the process not only in early ages where the capillary sorption is predominant but also for later and long times where the diffusive processes through the finer and gel pores are considered. The fitting of the model by computerized methods enables us to determine the parameters that characterize the process: i.e., the sorptivity coefficient (S) and diffusion coefficient (D). This allows the description of the process for all times and offers the possibility to know the contributions of both, the diffusive and capillary processes. The results show the influence of the curing regime and the preheating temperature on the behavior of GGBS mortars.

• Structural Monitoring and Maintenance
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• v.2 no.1
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• pp.35-48
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• 2015

The main objective of this study is to evaluate the long-term performance of various concrete composites in natural marine environment prevailing in the Gulf region. Durability assessment studies of such nature are usually carried out under aggressive environments that constitute seawater, chloride and sulfate laden soils and wind, and groundwater conditions. These studies are very vital for sustainable development of marine and off shore reinforced concrete structures of industrial design such as petroleum installations. First round of testing and evaluation, which is presented in this paper, were performed by standard tests under laboratory conditions. Laboratory results presented in this paper will be corroborated with test outcome of ongoing three years field exposure conditions. The field study will include different parameters of investigation for high performance concrete including corrosion inhibitors, type of reinforcement, natural and industrial pozzolanic additives, water to cement ratio, water type, cover thickness, curing conditions, and concrete coatings. Like the laboratory specimens, samples in the field will be monitored for corrosion induced deterioration signs and for any signs of failureover initial period ofthree years. In this paper, laboratory results pertaining to microsilica (SF), ground granulated blast furnace slag (GGBS), epoxy coated rebars and calcium nitrite corrosion inhibitor are very conclusive. Results affirmed that the supplementary cementing materials such as GGBS and SF significantly impacted and enhanced concrete resistivity to chloride ions penetration and hence decrease the corrosion activities on steel bars protected by such concretes. As for epoxy coated rebars applications under high chloride laden conditions, results showed great concern to integrity of the epoxy coating layer on the bar and its stability. On the other hand corrosion inhibiting admixtures such as calcium nitrite proved to be more effective when used in combination with the pozzolanic additives such as GGBS and microsilica.

• International Journal of Concrete Structures and Materials
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• v.18 no.2E
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• pp.97-102
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• 2006

In this study, the effect of supplementary materials(GGBS, PFA, SF) on sulfuric acid corrosion resistance was assessed by measuring the compressive strength, corroded depth and weight change at 7, 28, 56, 91, 180 and 250 days of immersion in sulfuric acid solution with the pH of 0.5, 1.0, 2.0 and 3.0. Then, it was found that an increase in the duration of immersion and a decrease in the pH, as expected, resulted in a more severe corrosion irrespective of binders: increased corroded depth and weight change, and lowered the compressive strength. 60% GGBS mortar specimen was the most resistant to acid corrosion in terms of the corroded depth, weight change and compressive strength, due to the latent hydraulic characteristics and lower portion of calcium hydroxide. The order of resistance to acid was 60% GGBS>20% PFA>10% SF>OPC. In a microscopic examination, it was found that acid corrosion of cement matrix produced gypsum, as a result of decomposition of hydration products, which may loose the structure of cement matrix, thereby leading to a remarkable decrease of concrete properties.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.115-121
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• 2015

The objective of this study is to present the design approach of low $CO_2$ concrete structures for reduction of $CO_2$ emissions. The design approach was implemented considering the system boundary for each processing presented in the ISO 13315-2. As for life-cycle inventory(LCI) for $CO_2$ assessment of concrete structures, data provided from domestic LCI DB was used. Based on the process presented in this study, case studies on the life-cycle $CO_2$ assessment of shear wall concrete structure was conducted. As substitution level of GGBS is 25%, the amount of $CO_2$ emissions and $CO_2$ uptake by concrete carbonation was decreased in the material, demolition and crushing, and transport phase. The amount of $CO_2$ emissions of column and total member was decreased by 26% and 22% respectively, compared to that of OPC.