• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.195-198
• /
• 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
• /
• 2001.05a
• /
• pp.641-646
• /
• 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
• /
• 1999.10a
• /
• pp.203-206
• /
• 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
• /
• 2002.10a
• /
• pp.275-280
• /
• 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
• /
• v.12 no.5
• /
• pp.367-375
• /
• 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
• /
• 2003.05a
• /
• pp.67-71
• /
• 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
• /
• v.3 no.3
• /
• pp.135-142
• /
• 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.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.1
• /
• pp.19-24
• /
• 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 Concrete Institute
• /
• v.26 no.4
• /
• pp.525-532
• /
• 2014

It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only, however, it is necessary to perform the research about structural shear behavior. Therefore, in this paper, 27 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35%, 50%, concrete compressive strength 20, 40, 60 MPa and 3 shear stirrups amounts. 27 test members were tested for shear behavior. From the test results, there were no differences between 35%, 50% high volume fly ash cement concrete and ordinary concrete without fly ash (FA=0%).

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2007.11a
• /
• pp.67-70
• /
• 2007

In this study, the characteristic of strength development of high volume fly ash concrete(HVFAC) was experimentally investigated. The production of one ton of portland cement releases about 0.87ton of CO2 into the atmosphere. HVFAC is an emerging material technology and is environmentally friendly because of its reduced use of portland cement, reduced CO2 emissions. For this purpose, two levels of W/B were selected. Seven levels of fly ash replacement ratios and two levels of silica fume replacement ratios were adopted. In the concrete mix, the water content of 125kg/m3 was used, which is less than that of usual water content. As a result, it was observed that the slump of concrete was increased with the increasing fly ash replacement ratio and when the silica fume was incorporated into the concrete, the slump was significantly decreased at the same condition. It appeared that the compressive strength gradually decreased with increasing fly ash replacement ratio at the early age, but the difference of strength up to replacement ratio of 50% was little at the age of 91 days because of the pozzolanic reaction of fly ash.