• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.117-120
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• 2004

Up to now, many researches have been performed md verified that many properties of concrete can be improved by using mineral admixtures such as blast furnace slag, silica fume, and expansive admixture. But it is not clear whether there is any need for entraining air to make a high strength concrete using expansive admixture and mineral admixtures to insure enough freeze-thaw resistance. this paper presents the strength and durability properties of high strength concrete using expasive admixtures and industrial by-products. It was observed from the test results that very high strength concrete$(W/B=20\%)$ is not needed to be air entrained and high strength concrete$(W/B=30\%)$ using expansive admixture and mineral admixtures is needed to be entrained $2\~4\%$ air.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.773-776
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• 2006

This experimental study is the fundamental report to use the ternary concrete. This study performed to know physical properties of ternary concrete according to replacement ratio of pozzolanic admixtures and curing temperature conjugation. To investigate Strength development properties of according to replacement ratio of pozzolanic admixtures, both fly ash replaced on portland cement in 5, 10 and 15% weight ratios and blast furnace slag replaced on the portland cement in 5, 15, 20, 30 and 40% weigt ratios was used. Also this is studied fresh and hardened concrete properties in condition of curing temperature $10^{\circ}C\;and\;20^{\circ}C$. The followings are the summary of which concluded in this study. Considering the concrete cured over 28 days compressive strength, most replacement ratios of pozzolanic admixtures were higher than plain concrete that. Compressive strength development properties of ternary concrete according to curing temperature conjugation were similar except for early age.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.709-712
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• 2006

It is necessary to develop a new technology for controling thermal cracking by hydration heat according to the increase construction of massive concrete structures, high strength concrete and early strength concrete. Therefore, it was investigated the characteristics of hydration heat generation of low heat concrete using hydration heat reducing admixtures in this study. To investigate the performance of hydration heat reducing admixtures, it was evaluated hydration heat according to the kind and replacement ratio of phase change material series I, II and the way of using hydration heat reducing admixtures in series III.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.113-119
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• 2010

This study presents experimental findings on the performance of cement concrete pavement incorporating mineral admixtures such as ground granulated blastfurnace slag and silica fume. Flexural strength, compressive strength, charge passed, diffusion coefficient of chloride ions and initial surface absorption of cement concrete pavement incorporating mineral admixtures were periodically measured and the corresponding results were compared to those of plain concrete pavement. As a result, strength behaviors of concrete pavement were dependent on the types of mineral admixtures. However, it was true that incorporation of silica fume had a beneficial effect on compressive strength development. Furthermore, the application of mineral admixtures led to a lower diffusion coefficient of chloride ions compared to plain concrete pavement. Based on the experimental results, the present study would be helpful to design high-performance cement concrete pavement.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.319-326
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• 2004

This paper investigates the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete replaced mineral admixtures for 3${\~}$4 replacement ratios under water-binder ratios ranged from 0.40 to 0.55. For the electro-migration test, Tang and Nilsson's method was used to estimate the diffusion coefficient of chloride ion. As a results, the water-binder ratios, kinds of mineral admixtures and replacement ratios, water curing periods had a great effect on the diffusion coefficient of chloride ion, and the optimal replacement ratios had a limitation for each mineral admixtures. Also, the use of mineral admixtures by mass(replacement of OPC) enhance the resistance ability against chloride penetration compared with the plain concrete. The compressive strength was shown related to the diffusion coefficient of chloride ion, the compressive strength increases with the diffusion coefficient of chloride ion decreasing. Below the 50 MPa, the variation of diffusion coefficient of concrete replaced mineral admixtures was bigger than that of plain concrete.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.63-70
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• 2006

This study tested the alkali-silica reactivity of various types of crushed stones, following the specifications of ASTM C 227 and C 1260, and the results obtained from the tests were compared. This study also analyzed the effects of particle size and grading of reactive aggregate based on the expansion of mortar-bar due to an alkali-silica. The effect of mineral admixtures to reduce the detrimental expansion caused by the alkali-silica reaction was investigated based on the method specified by ASTM C 1260. The mineral admixtures used in this study were fly ash, silica fume, metakaolin and ground granulated blast furnace slag. The replacement ratios of 0, 5, 10, 15, 25 and 35% were uniformly applied to all the mineral admixtures, and the replacement ratios of 45 and 55% were additionally applied for the admixtures that could sustain the workability at these ratios. The results indicate that replacement ratios of 25% for fly ash, 10% for silica fume, 25% for metakaolin and 35% for ground granulated blast furnace slag were the most effective in reducing the expansion due to the alkali-silica reaction under the experimental conditions of this study.

• The Journal of Engineering Geology
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• v.25 no.2
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• pp.179-188
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• 2015

Although permeating injection is ideal for grouting reservoir embankments, it is usually combined with fracturing injection for grouting, which can disturb the original soil. Compaction with low expansive pressure followed by grout injection can overcome this problem. An expansive compaction (EC) packer was developed in this work to easily apply sequential injection and compaction at a work site. Furthermore, to achieve compaction around the grouting hole, a mixture of expansive admixtures and grout was injected with the EC packer to trigger an increase in volume of the grout material. This work verifies the compaction effect of the EC packer and the expansive admixture. It reports the concepts of the EC packer, the range of expansive compaction, the effectiveness of injection, and the results of indoor tests performed to verify the effectiveness of the expansive admixtures. The indoor testing comprised a preparatory test and the main test. The preparatory test assessed the admixtures for their compaction effects, while the main test measured and analyzed the admixtures' expansive force, pressure, and compaction effect with a mold to verify the effectiveness of the compaction effect.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.31-32
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• 2011

Granulated slag from metal industries and fly ash from the combustion of coal are industrial by-products that have been widely used as mineral admixtures in normal and high strength concrete. Due to the reaction between calcium hydroxide and fly ash or slag, the hydration of concrete containing fly ash or slag is much more complex compared with that of Portland cement. In this paper, the production of calcium hydroxide in cement hydration and its consumption in the reaction of mineral admixtures is considered in order to develop a numerical model that simulates the hydration of concrete containing fly ash or slag. The heat evolution rates of fly ash- or slag-blended concrete is determined by the contribution of both cement hydration and the reaction of the mineral admixtures. Furthermore, the temperature distribution and temperature history in hardening blended concrete are evaluated based on the degree of hydration of the cement and the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.

• Journal of the Korea Institute of Building Construction
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• v.9 no.2
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• pp.85-91
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• 2009

W/C and unit volume, which significantly affect quality of concrete related to strength and durability, are regulated at below $185kg/m^3$ for regular concrete generally used in standard specification for constructions. The aim of this research is to develop chemical admixture and find out its potential use by identifying characteristics of admixtures added to soft concrete and hardening concrete, of which content ratio of component for each type of admixtures is subject to change in accordance with unit volume within KS' allowable range. Sodium gluconate, polyoxyethylene nonylphenyl ether, poly carboxylic copolymer in slump, which is characteristic of soft concrete, are deemed highly sensitive while there is no air entrainment except for $10\sim70%$ in WE, WR component content ratio and NP. In hardening concrete, strength in general showed higher action in compressive strength and tensile strength than in plain strength. Use of proper AE agent and AE water reducing agent at the same time is deemed to be used as chemical admixtures capable of manufacturing high-quality, high-quantity concrete.

• Computers and Concrete
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• v.32 no.2
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• pp.185-206
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• 2023

This article aimed to explore the optimization of mineral admixtures and retarding admixture for high-performance concrete. In essence, fresh concrete can be regarded as a mixture in which both coarse and fine aggregates are suspended in a cement-based matrix paste. Based on this view, the test procedure was divided into three progressive stages of binder paste, mortar, and concrete to explore their rheological behavior and mechanical properties respectively. At each stage, there were four experimental control factors, and each factor had three levels. In order to reduce the workload of the experiment, the Taguchi method with an L9(3⁴) orthogonal array and four controllable three-level factors was adopted. The test results show that the use of the Taguchi method effectively optimized the composition of high-performance concrete. The slump of the prepared concrete was above 18 cm, and the slump flow was above 50 cm, indicating that it had good workability. On the other hand, the 28-day compressive strength of the hardened concretes was between 31.3-59.8 MPa. Furthermore, the analysis of variance (ANOVA) results showed that the most significant factor affecting the initial setting time of the fresh concretes was the retarder dosage, and its contribution percentage was 62.66%. On the other hand, the ANOVA results show that the most significant factor affecting the 28-day compressive strength of the hardened concretes was the water to binder ratio, and its contribution percentage was 79.05%.