• Computers and Concrete
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• v.29 no.3
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• pp.169-186
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• 2022

Mortar is produced with different degrees of temperature and ratios of admixture materials. In order to produce strength mortar, the degree of temperature and the ratio of admixture materials must be optimized. This paper examines experimental effects by applying certain degrees of temperature and ratios of admixture materials to statistically understand the changes in the strength of mortar. The Taguchi method is used for the above-mentioned optimization problem. Firstly, factorial ANOVA is used to investigate the difference of means between the experiments. Due to the significant differences in obtained means, the regression analysis is applied. On the other hand, the effects of the varying degrees of temperature and admixture ratios are presented via 3D plots. Finally, the statistical results of ANOVA and Taguchi indicate that degree of temperature and the different ratios of admixture materials can affect the behaviour of mortar under the tests.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.89-92
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• 1999

The purpose of this study is to evaluate the capability to use with cement admixture materials because Paper Sludge Ash consists of Si, Ca and Al which are chief content in Pozzolan. For the derivation of Pozzolanic reaction in Paper Sludge Ash, it is measured compressive strength on cement mortar which is replaced mixing of Paper Sludge Ash and inorganic admixture ; ie, gypsum, lime and slaked lime, regularly. In the result of test, the strength decrease remarkably when cement is only replaced with Paper Sludge Ash, but the strength is almost equal when cement is replaced with Paper Sludge Ash is mixed with inorganic admixture material in proportions of 5~15%. Consequently, It is possible to use Paper Sluge Ash with admixture materials of cement.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.79-86
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• 2004

The purpose of this study was the development of a recycling process to recover the hydraulic properties of hydration products which account for a large proportion of cementitious powder from concrete waste. This process was performed to recycle cementitious powder as recycle cement. Therefore, after the theoretical consideration of the properties of recycle process of recycled aggregates and cementitious powder, we investigated the hydraulic properties of cementitious powder under various temperature conditions in hardened mortar which was modeled on concrete waste. And we analyzed properties of chemical reactions of recycled cement with admixture materials such as Fly-Ash, Blast Furnace Slag As a result of the experiment, the most effective method to recover hydraulic properties of the cementitious powder from concrete waste was condition of burning at 700℃ for 120 minute. And it is shown that the fluidity of mortar was decreased rapidly when the burning temperature of recycle cement was increased. However, the compressive strength and fluidity were improved significantly when admixture materials such as Fly-Ash or Blast Furnace Slag was added.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.23-31
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• 2007

To examine the effects of chemical admixture on the fluidity and strength development of high chloride cement, experiments were conducted in which lignosulfonate (LS), naphthalenesulfonate (NS), and polycorboxylate (PC) were each added in standard and excessive amounts, and the results were as follows. 1. Because adding KCl to NS causes a decrease in flow, adding PC is better in maintaining high cement fluidity. 2. When cement contained much chloride comes in contact with water, hydration begins 4 h after contact and securing workability becomes difficult, but by adding PC, workability can be secured to 10 h. 3. The bound water ratio and compressive strength in aging 3 days occupy $70\sim80%$ of those in aging 28 days, and the early compressive strength increases not only by adding KCl, but also by chemical admixture. 4. Although compressive strength development is excellent in NS, PC, if NS is added excessively, hydration becomes slow and while the pore structures become slightly minute, the strength development decreases due to severe setting retardation.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.87-93
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• 2008

With an increased use of alternative aggregate due to exhaustion of quality aggregate resources, the amount of used crushed aggregates have been increased and as a result, development of admixture materials has also been improved and its amount of use is increasing from day to day in order to secure quality in concrete. Accordingly, the purpose of this study is to make concrete of good quality by using chemical admixture developed in this study by replacement rate of fine aggregate. At first, susceptibility, compressive strength ratio and length change ratio in both fresh and hardened concrete were evaluated according to corresponding regulation. As for high performance related regulation, APC NO.3 and PC series were going to rule, and as for AE agent regulation, replacement ratio of fine aggregate of high performance chemical admixture was 10:0 and other chemical admixture met quality regulation for AE agent.

• Computers and Concrete
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• v.2 no.5
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• pp.381-388
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• 2005

This paper presents the results of a study on binary blends of Portland cement and fly ash with complex admixture used for the concrete structures to meet specific performance objectives in east coastal area of China. The concretes were evaluated for workability, strength, water permeability, drying shrinkage, sulfate resistance and electrical resistance. Environmental Scanning Electron Microscopy (ESEM) was used to examine the microstructure of concrete made by complex admixture compared with control batches without complex admixture. The combined efforts of fly ash and complex admixture led to an improvement in the workability, strength and durability.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.21 no.5
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• pp.117-124
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• 2019

When manufacturing concrete, several mineral admixture is added to improve the basic physical property and durability and to make economical concrete. Such mineral admixture includes fly ash, granulated blast furnace slag, silica fume, etc., and not only the studies about mixing these mineral admixtures but also the studies for the development of new materials have been steadily in progress. Recently, some researchers have found, as a part of the development of new materials, the rice straw ash can also be used as a pozzolanic material for concrete considering similar chemical properties of rice straw ash to that of rice husk ash. But there has been insufficient amount of study about it. So, this study was to investigate the possibility as mineral admixture of agriculture by-product, by analyzing properties of concretes using rice straw ash with replacement ratio in comparison with other mineral admixture. In order to measure amount of SiO2 of rice straw ash, XRF(X-ray fluorescence) analysis was tested. For the measure pozzolanic reaction of rice straw ash, pH change and color change was tested according to curing day. Also to evaluate properties of concrete using rice straw ash, slump test, air contents test and compressive strength was tested.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.879-884
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• 2005

The setting time is a very important factor affecting the quality of tunnel lining and reinforcement of inclined slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of cement mixed a accelerating admixture (AA) was performed using Gillmore and Vicat needle test methods. For both test methods, the setting time for addition at a time was better than post addition regardless of initial setting and final setting. For Gillmore needle test method, two types of measuring methods were selected and it is noted that setting time with cement type under the same accelerating admixture can be different. Accordingly, manufacturing company shall develop a less sensitive accelerating admixture to cement type. For Vicat needle test method, six types of measuring methods were used and a proper measuring method of the admixture were proposed as follows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate its properties, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.317-320
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• 2004

The setting time is very important factor affecting the quality of tunnel lining and reinforcement of sloped slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of a cement accelerating admixture was performed. Six types of measuring methods were checked and a proper measuring method of the admixture were proposed as fellows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate the properties of it, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.181-188
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• 2000

This study deals with the method of test for waterproof agent and admixture of cement, and especially, the effect in bond strength between waterproofing layer and mortar of concrete substrate in building construction. The purpose of this study is that it makes the estimation value of bond strength of concrete wall and anticorrosive when coated waterproof agent and admixture of cement as waterproofing materials for durability performance estimation depend on concrete watertighness.