• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.185-191
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• 2017

The objective of this paper is to investigate the effect of waste refractory powder(WRP) and desulfurization gypsum(FGD) as activators on the flow properties and the strength development of high volume blast furnace slag mortar incorporating illite(BSM) having adsorption and deodorization. To fabricate the BSMs with 60% of W/B, blast furnace slag are incorporated with 45% and 65%, respectively. WRP and FGD are substituted from 5 to 10%. Test results indicate that the flow is decreased with increase of WRP and FGD, while increase of WRP and FGD enhance the compressive strength due to accelerated reaction of blast furnace slag, The use of illite results in a decrease of compressive strength. pH has increasing tendency until 7days, while it has reduction. In this paper, optimal dosages of WRP and FGD are believed to be around 5% each.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.229-240
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• 1987

Carbonation of concrete is one type of a chemical process. The reaction mechanism is very complex for the case when low-calcium fly ash and blast furnace slag is added. When fly ash and blast furnace slag is used as an admixture in concrete, they improve compressive strength in the long term, permeability and chemical resistance of concrete by a pozzolanic reaction and latent hydraulic property. On the other hand, the pozzolanic reaction of fly ash and latent hydraulic property of the blast furance slag leads to a reduction of the alkalinity of the concrete. It has been pointed out that this will accelerate the carbonation of the concrete and the corrosion of reinforcement steel embedded in the concrete. In order to clarify the effect of fly ash and blast furance slag on the carbonation of concrete, an accelerated carbonation testing of concrete was carried out by varying the conditions of concrete and the initial curing period in water. The test results of accelerated carbonation were compared to the carbonation test results of concrete stored for 15 years in open air, but protected from rain. As a result, the equation for the rate of carbonation based on compressive strength of concrete was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.163-169
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• 2009

The research performed a test concerning the fluidity and strength of concrete manufactured by combining lime stone power, fly ash, and blast furnace slag into two and three component systems, aiming at evaluating rheological and dynamic properties of concrete by manufacturing High Flowing Self-Compacting according to the strength changes of three levels. As a result of the research, for High Flowing Self-Compacting of 30 MPa, the combination of lime stone power 20% and fly ash 30% for securing quality and strength and adjusting viscosity satisfied the required performance. For High Flowing Self-Compacting of 50 MPa, the combination of blast furnace slag 10% and fly ash 20% satisfied the fluidity and strength of the requirement performance. Also, for 70 MPa that has many power contents, the combination of blast furnace slag 20% and fly ash 10% for the increase of fluidity and the reduction of viscosity satisfied the required performance. It is judged that fly ash in all combinations can be used to secure viscosity and reduce concrete amount. In addition, it is judged that for High Flowing Self-Compacting according to the levels of compressive strength the combination of three component system including fly ash is more appropriate than the combination of two component system.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.405-412
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• 2008

Six alkali-activated (AA) concrete mixes were tested to explore the significance and limitations of developing an environmental friendly concrete. Ground granulated blast-furnace slag and powder typed sodium silicate were selected as source material and an alkaline activator, respectively. The main parameter investigated was the replacement level of lightweight fine aggregate to the natural sand. Workability and mechanical properties of lightweight AA concrete were measured: the variation of slump with time, the rate of compressive strength development, the splitting tensile strength, the moduli of rupture and elasticity, the stress-strain relationship, the bond resistance and shrinkage strain. Test results showed that the compressive strength of lightweight AA concrete sharply decreased when the replacement level of lightweight fine aggregate exceeded 30%. In particular, the increase in the discontinuous grading of lightweight aggregate resulted in the deterioration of the mechanical properties of concrete tested. The measured properties of lightweight AA concrete were also compared, wherever possible, with the results obtained from the design equations specified in ACI 318-05 or EC 2, depending on the relevance, and the results predicted from the empirical equations proposed by Slate et al. for lightweight ordinary Portland cement concrete. The stress-strain curves of different concrete were compared with predictions obtained from the mathematical model proposed by Tasnimi. The measured mechanical properties of lightweight AA concrete generally showed little agreement with the predictions obtained from these equations.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.45-54
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• 2016

In this study, the construction method of new underground continuos impervious wall that the bentonite slurry keeps the stability of excavated trench and the mixture of cement and bentonite plays a role as a constituent of impervious wall in the trench. The merit of homogeneity of the method so called as a cement-bentonite slurry wall enables to accurately make an estimation of hydraulic conductivity of the walls compared with that by other general grouting methods and to verify their waterproof efficiency without difficulty at the design stage. The use of cement-bentonite slurry walls for the containment of groundwater flow has also proven a cost-effective impervious wall technology by employing the simple combination of construction equipments and easy and fast construction procedures. The engineering characteristics of cement-bentonite impervious wall obtained by carrying out the laboratory experiments under various conditions. This study reveals the effect of variation of constituent materials and their mixing methods (Water-Cement-Bentonite) on the engineering characteristics of a composition. Also, this study makes some recommendations on the optimum mixing ratio and mixing sequence for the best quality at the site. That is the most important factors to estimate the construction cost and design of the technique. The comparison is lastly made to evaluate the effect of ordinary Portland and blast furnace slag cement as a bonding material on the behavior of impervious walls.

• Journal of the Korean Geotechnical Society
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• v.34 no.6
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• pp.17-24
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• 2018

In this study, static load test and dynamic load test were performed to evaluate pile-filling material (ZA-Soil) of soil-cement injected precast pile method which was developed by using the ash of circulating fluidized boiler as a stimulant for alkali activation reaction of blast furnace slag. As a result of the static load test, the allowable bearing capacity of pile was 1,350 kN, which was the same as the result of using ordinary portland cement. And total settlement was 6.97 mm, and net settlement was 1.48 mm. These are similar to the total settlement, 7.825 mm, and net settlement, 2.005 mm of ordinary portland cement. As a result of the dynamic load test and CAPWAP analysis, the skin friction was 375.0 kN, the end bearing capacity was 3,045.9 kN, and the allowable bearing capacity was 1,368.36 kN. These results are similar to the results of using ordinary portland cement as pile-filling material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.195-202
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• 2004

In this study, it was founded to make the optimal mixture for producing concrete which is self-compacting, yet, and generates low heat of hydration by using flyash, blast furnace slags and limestone powders as binders in addition to cement while using super-plasticizers and viscosity agents as admixture agents. The structural behaviors of the concrete produced with the selected mixture were compared with those of the concrete currently using for construction of nuclear power plants. The study shows that the blended high fluidity concrete including limestone is better in workability and durability than the concrete currently in use for nuclear power plants.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.176-177
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• 2021

In order to compensate for the defects of concrete made using only Portland cement, three-component powder mixed with blast slag and fly ash, and four-component powder concrete mixed with silica fume are being produced. When each of the admixtures is used alone, the above-described excellent performance is expressed and up to 70% of the powder is used. These technologies are also contributing to the reduction of greenhouse gases under Act on Low Carbon. Green Growth. However, calcium hydroxide is consumed as a stimulator or reaction in the case of silica fume, which causes latent hydroponicity of slag, pozzolane reaction, and silica mixtures represented by fly ash. It is known that the consumption of calcium hydroxide affects the alkalinity of concrete. As a result, the carbonation resistance is significantly lower among the durability of concrete. Research on quantification of such effects is insufficient. In this study, an experiment was conducted to quantify calcium hydroxide of the three-component and four-component powder paste using thermal analysis equipment (DTG), and the effect of the mixing amount was discussed.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.343-351
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• 2015

Currently, lots of researches have been performed for reducing cement usages due to increasing social/engineering problems caused by $CO_2$ emission. Supplementary cement materials like fly ash, slag, and silca fume are usually employed for cement replacement, and nowadays rice husk ash (RHA) is widely studied for enhancement of concrete performance as mineral admixture. In this paper, concrete samples with RHA and SF which is known for its engineering advantages are prepared and a resistance to chloride attack is evaluated in early-aged concrete. For the work, replacement ratios of 10~30% for RHA concrete and 2~8% for SF concrete are considered, and various durability tests such as density, void, sorptivity, current measurement, and chloride diffusion coefficient are performed including mechanical test like compressive and tensile strength. Replacement of RHA 10~15% shows better improvement of corrosion resistance and strength than that of SF 2~4% and normal concrete, which shows a strong applicability for utilization as construction materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.697-700
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• 2008

Recently, high strength, flowability, and durability of concrete were required according to increase of large scale and high rise structure. However, cracks occurred easily on the high performance concrete. In this reason, using expansion agent for reducing shrinkage cracks were increased, but it did not consider on durability of high performance concrete. Accordingly, this study1 investigated the resistance of shrinkage and damage form salt by mixing CSA expansion agent on the blast-furnace slag cement and mixed cement for the low heat of hydration by three components. The cases that 8% of expansion agent was mixed and the proportion was OPC were expanded till 43.7 times compared with control concrete. For the resistance to the damage of salt, it was improved when mixing ratio was incresed and the maximum size of coarse aggregate growed bigger. In this study, the resistance to the damage of salt of the cases that 8% of expansion agent was mixed was improved about 16% compared with control concrete.