• Computers and Concrete
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• v.5 no.1
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• pp.75-88
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• 2008

This paper presents a mathematical model for strength and porosity of mortars made with ternary blends of ordinary Portland cement (OPC), ground rice husk ash (RHA) and classified fly ash (FA). The mortar mixtures were made with Portland cement Type I containing 0-40% FA and RHA. FA and RHA with 1-3% by weight retained on a sieve No. 325 were used. Compressive strength and porosity of the blended cement mortar at the age of 7, 28 and 90 days were determined. The use of ternary blended cements of RHA and FA produced mixes with good strength and low porosity of mortar. A mathematical analysis and two-parameter polynomial model were presented for the strength and porosity estimation with FA and RHA contents as parameters. The computer graphics of strength and porosity of the ternary blend were also constructed to aid the understanding and the proportioning of the blended system.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.345-350
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• 1997

This paper describes an experimental study on the strength and flexural toughness of steel fiber reinforced concrete using fly ash. The fly ash contents were varied from 0% to 20% of cement weight to explore the effect of fly ash addition with steel fiber reinforced concrete. as the result, the tensile strength, flexural strength and flexural toughness were increased remarkably as steel fiber contents were increased to 2.0 vol.%. Also, the steel fiber reinforced concrete containing 10% fly ash developed the highest strength. In the same contents of steel fiber, the flexural toughness characteristics show excellent when fly ash contents were 10% and steel fiber contents were 1.5 vol%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.48-49
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• 2015

High-calcium fly ash (FH) is widely used as mineral admixtures in concrete industry. In this paper, a hydration model is proposed to describe the hydration of high-calcium fly ash blended-cement. This model takes into account the hydration reaction of cement, the chemical reaction of fly ash, and reaction of free CaO in fly ash. Using the proposed model, the development of compressive strength of FH blended concrete is predicted using the amount of calcium silicate hydrate (CSH). The agreement between simulation and experimental results proves that the new model is quite effective.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.103-104
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• 2017

This paper is to provide a method to prevent air loss of the concrete using reject ash based ternary blended aggregate due to absorption of AE agents by reject ash by adding AE agents into reject ash before mixing concrete. Test results indicate that air loss due to presence of reject ash in ternary blended aggregate can be recovered by over use of AE agents into aggregate directly before mixing.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.6
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• pp.609-609
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• 1998

This paper surveys the effect of rice straw ash solution to the physical properties of Sappan Wood dyeing fabrics. In the quantitative analysis of rice straw ash solution, the quantities of absorbed ingredients in fabrics were increased by bath pull treatment but the amount of absorption(K/S value) was increased by bath pH4.5 treatment. This is related to the metal ion. Among the metal ion, effect of Fe iou and Al ion were related. In case added extracted dye solution to mordants, the color dye solution became dark and increased reddish. The changes of mechanical properties of fabrics tensile resilience, bending rigidity(B), compressional resilience(RC) were increased. Generally mechanical properties were increased by rice straw ash solution treatment, specially bath pH9 treatment. Rice straw ash solution treatment of dyeing fabrics made the improvement in tensile strength and elongation and in the amount of absorption, dye ability, color fastness, mechanical properties, tensile strength, elongation.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.6
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• pp.699-705
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• 1998

This paper surveys the effect of rice straw ash solution to the physical properties of Sappan Wood dyeing fabrics. In the quantitative analysis of rice straw ash solution, the quantities of absorbed ingredients in fabrics were increased by bath pull treatment but the amount of absorption(K/S value) was increased by bath pH4.5 treatment. This is related to the metal ion. Among the metal ion, effect of Fe iou and Al ion were related. In case added extracted dye solution to mordants, the color dye solution became dark and increased reddish. The changes of mechanical properties of fabrics tensile resilience, bending rigidity(B), compressional resilience(RC) were increased. Generally mechanical properties were increased by rice straw ash solution treatment, specially bath pH9 treatment. Rice straw ash solution treatment of dyeing fabrics made the improvement in tensile strength and elongation and in the amount of absorption, dye ability, color fastness, mechanical properties, tensile strength, elongation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.129-130
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• 2021

In order to solve the problem of low early-age compressive strength of high volume fly ash concrete. This paper studies the effect of 2% sodium sulfate (Na₂SO₄) as a chemical activator on the paste with 40% fly ash content and a water-binder ratio of 0.30. The results indicate that the addition of Na₂SO₄ can effectively improve the early-age compressive strength of the fly ash-cement system, and the strength improvement rate on the first day reached nearly 70%. In addition, calorimetric analysis reveals that the incorporation of Na₂SO₄ promotes the early hydration of cement and fly ash, increases the cumulative hydration heat and delays the heat peak of the aluminum phase.

• Computers and Concrete
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• v.19 no.6
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• pp.625-630
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• 2017

In this paper, 54 pull-out specimens and 36 cubic specimens with different replacement ratios of fly ash in the concrete (i.e., 0%, 20%, 30%, 40%, 50%, 60%) were fabricated to evaluate the bond at the interface between fly ash concrete and steel rebar. The results showed that the general shape of the bond-slip curve between fly ash concrete and steel rebar was similar to that for the normal concrete and steel rebar. The bond strength between fly ash concrete and the steel rebar was closer to each other at the same rebar diameter, irrespective of the fly ash replacement percentage. On the basis of a regression analysis of the experimental data, a revised bond strength mode and bond-slip relationship model were proposed to predict the bond-slip behaviour of high volume fly ash concrete and steel rebar.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1051-1060
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• 2008

The use of the coal ash for surcharge material, in a view of the environmental aspect, can decrease amount of the reclamation through recycling waste materials as well as prevent a destruction of the ecosystem attributed to sand picking. In addition, it can reduce both unit cost of material and construction expenses. In this study, new construction material as alternative surcharge material using coal ash, which is by-product from thermoelectric power plant, were developed. Mixing ratios of fly ash and bottom ash derived from the coal ash in Samchunpo thermoelectric power plants were determined. Furthermore, mixing conditions depending on the ratios of the cement and gypsum used for chemical additive were determined too. Uniaxial compression strength tests were conducted at different mixing conditions and Design graph of optimum mixing ratio at each required strength for economic efficiency is indicated in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.565-568
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• 2008

Because of low early compressive strength, the usage of fly ash is subject to restriction in comparison with blast-furnace slag powder. Therefore, high amount of fly ash is reclaimed in landfill in face of better economical efficiency and more production. In this paper, the primary aim is to determine to what the basic material characteristics of fly ash concrete is affected by activator, the second aim is to check a possibility of increase in fly ash application. This study show that compared with fly ash concrete using general admixture, fly ash concrete using activator have higher early compressive strength under similar slump, air content, loss. If additional study will inspect performance of activator in various factor, expansion of application of fly ash concrete using activator can be possible.