• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.195-198
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• 1999

Fly ash is the most common artificial pozzolan, which is a material precipitated electrostatically from the exhaust gases of coal-fired power stations. Fly ash can be used as the supplementary material as well as the material for high performance concrete and hence, the development of high-volume fly ash concrete is imperative. In this study, the characteristics of drying shrinkage of high volume fly ash concrete is investigated. It is found from test results that as the replaced amount of fly ash in concrete is increased, drying shrinkage of concrete is reduced.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.641-646
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• 2001

Generally, when Fly-Ash was used as replacement material of cement in concrete, it might occur retardation of setting and hardening. So, it is unable to use a large amount of Fly-Ash as replacement for cement. However, if it is used as replacement material of fine aggregate in concrete, we can use a large amount of Fly-Ash and settle a problem of natural-aggregate exhaustion. Furthermore, engineering properties of High Volume Fly-Ash Concrete Is better than that of plain concrete But, the larger Fly-Ash is replaced, the more fluidity of High Volume Fly-Ash Concrete decrease, because porous organization of Fly-Ash adsorb water and Superplasticizer. In this study, after appending additional water to High Volume Fly-Ash Concrete in proportion to weight of Fly-Ash, we intend to find proper ratio which doesn't affect strength and satisfy fluidity As a result of this study, it was found that fluidity of mortar with 25~28 percentage of additional water was satisfied with fluidity of plain mortar, and compressive strength of that was similar to plain mortar's

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.203-206
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• 1999

An experimental study is carried out to investigate the characteristics of concrete containing high volume fly ash. The compressive and tensile strength of fly ash concrete is slightly lower than those of ordinary concrete between 7and 28 days, however, the long-term compressive strength is significantly higher at 180 days. In durability, the high volume fly ash concretes are generally higher resistance of freeze and thaw and lowe chloride penetration, however, the depth of carbonation is increased with increasing fly ash content.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.275-280
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• 2002

To study of high volume fly -ash concrete replace cement and fine aggregate together. Proportion consideration economy cost and performance improve replacement high volume fly-ash. Experimentation study of high-strength which cement about fly-ash replacement maximum 50%Flash concrete tested slump, air contest, setting and Hardening concrete tested day of age 1, 3, 7, 28, 91 compression strength in underwater curing. Purpose of study is consultation materials in field that variety of fly ash replacement concrete mix proportion comparison and valuation.

• Advances in concrete construction
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• v.12 no.5
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• pp.367-375
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• 2021

This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.67-71
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash at the same time was used. It was used that the adiabatic temperature rise of concrete about the mass member which bad been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive streneth's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the tine to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.135-142
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash was used at the same time. It was used that the adiabatic temperature rise of concrete about the mass member which had been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive strength's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the time to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.3
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• pp.81-90
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• 1999

The purpose of this study is to examine the uses of fly ash asa type of construction material. This paper presents the results of research performed to identify optimum mix proportions for production of lowable fill with high volume fly ash content . The fly ash used in this study met the requirements of KS L 5405 and ASTM C 618 for Class F material. The flowable fill with high volume fly ash content was investigated for strength and flowability characteristics. Tests were carried out on flowable fill designed to have 10 ~15kgf/$\textrm{cm}^2$ compressive strength at 28 days with fly ash contents of approximately 260kgf/㎥. Slump was held at 25$\pm$1cm for all mixtures produced to range from 5kgf/$\textrm{cm}^2$ to 14kgf/$\textrm{cm}^2$ compressive strengths at 28 days. To produce flowable fill with high volume fly ash , first the influential variables were identified in an experimental study based on factorial design. Among the proportioning variables investigated, cement ,fly ash, and sand contents were found to have statistically significant effect on strength and slump of flowable fill . Subsequently, response surface analysis techniques were used to devise an experimental program that helped determine the optimum combinations of the selected influential variables based on material properties and cost. The optimized flowable fill were then technically evaluated. It is shown that flowable fill has acceptable compressive strength , slump flow, hardening time, and permeability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.19-24
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• 2016

Several researches on high volume fly ash concrete have been conducted to investigate its fundamental material properties such as slump, strength and durability and however, research on the structural behavior of bond strength is essential for the application of this high volume fly ash concrete to structural members because of the necessity of reinforcement. But the exact design code for application and researches on the bond behavior of high volume fly ash concrete lack yet. To achieve such a goal, this paper evaluates experimentally the bond behavior of high volume fly ash concretes by direct pull-out test and compares between the current test results and existing research results. By the test results, it is shown that the bond behavior of high volume fly ash concrete is similar to that of general concrete. And by the comparison between test and existing research, it is shown that bond stress of high volume fly ash concrete is underestimated, as the embedment length gets longer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.95-102
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• 2022

Recently, there has been a growing interest in reducing greenhouse gases in all industrial fields. In the construction industry, studies have been conducted for the use of high-volume fly ash concrete to replace cement with fly ash. Quantitative measurements of cement hydration and fly ash reactivity enable a clear understanding of the strength development mechanism of high-volume fly ash concrete. It is very difficult to describe the reactivity in a simple way because the hydration and pozzolanic reactions of cement paste containing fly ash are very complex and the composition of the hydration product cannot be accurately determined. This study investigated the hydration and mechanical properties of high volume fly ash (HVFA) cement according to the substitution rate of fly ash (FA). The hydration degree of cement and the reactivity of FA were evaluated through the selective dissolution method and the non-evaporable water content of the paste according to age. In addition, compressive strength was measured using HVFA mortar specimens according to age. As a result of the experiment, as the substitution rate of fly ash increased, the hydration degree of cement increased, but the reactivity of FA decreased.