• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.323-330
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• 2019

The cement industry is considered a major industry for reducing greenhouse gases, increasing the amount of binding materials that can replace cement in concrete is known as the most effective method for reducing carbon dioxide. Therefore, research is being carried out to utilize large quantities of by-products that can be used as alternatives to cement. However, there are problems with reduced strength at early age and retarded setting for major reasons that do not increase the amount of mixture of binders used to replace cement. Thus, in this study, normal cement and high-fineness cement were used and physical properties were reviewed by placing differences in fly ash usage depending on the type of cement. As a result, the characteristics of strength were similar, and the hydration temperature was the same level. Also, the durability test showed that the length change, carbonation resistance were better than those of normal cement. Therefore, it is confirmed that the use of high-fineness cement is effective to reduce the amount of cement used and using more by-products.

• Computers and Concrete
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• v.10 no.4
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• pp.391-407
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• 2012

Utilization of supplementary cementing materials (SCM) by the cement industry, as a highly promising solution of sustainable cement development aiming to reduce carbon dioxide emissions, necessitates a more thorough evaluation of these types of materials on concrete durability. In this study a comparative assessment of the effect of SCM on concrete durability, of every cement type as defined in the European Standard EN 197-1 is taking place, using a software tool, based on proven predictive models (according to performance-related methods for assessing durability) developed and wide-validated for the estimation of concrete service life when designing for durability under harsh environments. The effect of Type II additives (fly ash, silica fume) on CEM I type of cement, as well as the effect of every Portland-composite type of cement (and others) are evaluated in terms of their performance in carbonation and chloride exposure, for a service life of 50 years. The main aim is to portray a unified and comprehensive evaluation of the efficiency of SCM in order to create the basis for future consideration of more types of cement to enter the production line in industry.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.63-70
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• 2017

When industrial by-products like slag and fly ash are using in concrete with cement, it improves strength and durability against external deterioration factors by densifying the structure through potential hydraulic and pozzolanic reaction. But it has been pointed out that high dependence on the quality variation and the curing condition using a admixure material for concrete. In this study, the characteristics of internal micropore structure according to curing condition were analyzed for pastes and mortar specimens under using blast furnace slag powder. As a result, the variation of compressive strength and the internal microstructure were observed according to curing conditions by binder type. Particularly, using blast furnace slag powder, decrease in compressive strength were clearly observed in indoor and carbonation curing compared with water curing. The pore structure analysis also clearly observed the decrease of the gel pore existing in the CSH hydrate layer and the increase of the capillary pore in indoor and carbonation curing compared with water curing condition.

• Advances in concrete construction
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• v.9 no.2
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• pp.139-147
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• 2020

This paper reports the effect of Rice Husk Ash (RHA) in geopolymer concrete on strength, durability and microstructural properties under ambient curing at a room temperature of 25℃ and 65±5% relative humidity. Rice husk was incinerated at 800℃ in a hot air oven. and ground in a ball mill to achieve the required fineness. RHA was partially added in 10, 15, 20, 25, 30 and 35 percentages to fly ash with 10% of GGBS to produce geopolymer concrete. Test results exhibit that the substitution of RHA in geopolymer concrete resulted in reduced strength properties during initial curing. In the initial stage, workability of GPC mixes was affected by RHA particles due to the presence of dormant particles in it. It is evident from the microstructural study that the presence of RHA particles densifies the matrix reducing porosity in concrete. This is due to the presence of RHA in geopolymer concrete, which affects the ratio of silica and alumina, resulting in polycondensation reactions products. This study suggests that incorporation of rice husk ash in geopolymer concrete is the solution for effective utilization of waste materials and prevention of environmental pollution due to the dumping of industrial waste and to produce eco-friendly concrete.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.541-550
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• 2011

Many researches have been performed on concrete with fly ash and bottom ash. However researches on concrete with pond ash (PA) and its application to RC (Reinforced Concrete) structure are limitedly carried out. This paper presents an applicability of PA concrete in construction of real size structure. Referring to the previous study, 2 domestic PA samples with normal performance are selected and 2 replacement ratios (25% and 50%) to fine aggregate are considered for 5 PA concrete structures consisting of column, slab, and wall. In order to evaluate the property of fresh concrete, several tests including air content, slump, and setting time are performed. Using cored out samples from hardened PA concrete structure, tests for strength, resistance to carbonation and chloride penetration are carried out and compared with control samples. Additionally, tests for rebound hardness, drying shrinkage, and hydration heat are performed for PA concrete structure. The test results showed that PA concrete has reasonable strength and durability performances compared to those of normal concrete. Therefore, its potential application to RC structure is promising. The PA aggregate can be more actively used for RC structures with better quality control for content of fly ash, bottom ash, and unburned carbon.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.349-355
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• 2016

This study is about the reuse of bottom ash, which is released as a necessity in thermal power plant. In general, coal-ash are classified as fly-ash, bottom-ash, cinder-ash. Of these, a large amount of fly ash is being recycled as cement substitutes. While, recycling rates of bottom ash are the lowest due to its porosity and high absorption. In this study, the durability of the concrete using bottom ash as a concrete fine aggregate was evaluated. The using level of the bottom ash ranges to step-by-step from 0% to 30%. According to the result of the durability test, regardless of the presence of the bottom ash, freeze-thaw durability could be secured by air entrainment. In case of the resistance to chloride ions penetration, the length change, and the effects on heavy metals, the replacement of bottom ash as fine aggregate was not critical. Although carbonation penetration was higher as the replacement level of bottom ash increased, the experiment showed that it could be possible to use bottom ash as concrete fine aggregate with proper mix design.

• Resources Recycling
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• v.19 no.5
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• pp.50-57
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• 2010

Ternary blended concrete(TBC), which contains both fly ash and granulated blast furnace slag, has an initial cost effective and is environment friendly. Furthermore, it has a lot of technical advantages such as the improvement of long term compressive strength, high workability, and the reduction of hydration heat. However, as the use and study on the performance of ternary blended concrete is limited, it is low short term compressive strength. This study was performed to evaluate the characteristics which are a long and short term compressive strengths, permeability and chemical attacks resistance of hardened high early concrete containing slag powder and fly-ash using high early strength cement(HE-TBC). Replacement rate of FA is fixed on 10% and replacement rate of slag powder are 0%, 10%, 20% and 30%. The test results showed that compressive and flexural strength of HE-TBC increased as the slag contents increased from 0% to 30% at the short term of curing. The permeability resistance of HE-TBC(fly ash 10%, blast 30%) was extremely good at the short and long terms. However, high early strength ternary blended concrete had weak on carbonation of chemical attack.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.340-349
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• 2013

The present paper investigates the availability of seawater as the absorbents to capture carbon dioxide ($CO_2$) emitted from the coal fired power plant (CFPP). For the purpose of the study, readily obtainable alkali materials in CFPP such as coal fly ash (FA), NaOH and $Ca(OH)_2$ are added to seawater to prepare the absorbents and their $CO_2$ capture performances are discussed. FA can be effectively used the additives to increase $CO_2$ capture capacity of seawater to a some extent. This is ascribed that some alkali components in FA are leached into seawater and they contribute to $CO_2$ capture in the solution. However, their leaching amount and rate are restricted by the various ions in seawater. The performance of NaOH added seawater is even lower than that of NaOH added water because $OH^-$ is substantially consumed on $Ma(OH)_2$ production prior to carbonation. $CO_2$ absorption capacity of $Ca(OH)_2$ added seawater is slightly larger than that of $Ca(OH)_2$ added water. This is because that $Ca^{2+}$ which originally present in raw seawater can participate in carbonation reaction.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.135-145
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• 2016

MgO recently has been regarded as the alternative material for replacement of cement. The aim of this study is to investigate the effects of accelerated carbonation on the strength development of MgO-based binder which is binary mixtures of magnesium oxide (MgO) with portland cement (PC) or ground granulated blast furnace slag (GGBS) or fly ash (FA). The compressive strengths of all binders were higher in the 20% $CO_2$ condition and for longer curing time. The strength were generally higher as the following order: MgO/PC > MgO/GGBS > MgO/FA system. The binder composed of 20% MgO and 80% PC showed highest compressive strength (38.0MPa) which was higher than PC. The correlation analysis of the porosity and compressive strength showed that compressive strength was higher when porosity was lower. The hydration and carbonation products of MgO including brucite ($Ca(OH)_2$), magnesite ($MgCO_3$) and nesquehonite ($MgCO_3{\cdot}3H_2O$) presumably filled the pores and contributed to strength development. Thermogravimetric analyses elucidated that 0.34 kg of $CO_2$ could be stored the 50% MgO/50% PC binder which performed the maximum $CO_2$ uptake at 20% $CO_2$ condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.445-448
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• 2008

It is essential that concrete component is made up with aggregate, cement and water. But today, Public concern is increasing of a variety structure and ocean environmental, resource recycle. Also, According to heat of hydration rising, Concrete is make a causative of concrete-crack. Concrete-crack cause a falling-off in quality of concrete. consequently, High-performance concrete is evaluated by concrete material properties and carbonation resistance with different admixture(fixing fly-ash 20%), granulated blast furnace slag replacement ratio (30%, 45%) different W/B (26%, 30%, 34%) and XRD(X-ray Diffraction) analysis.