• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.365-371
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• 2020

In this study, in order to recycle the stems of opuntia cactus discarded after harvesting the fruit, the cactus stems were powdered and applied as a cement-based admixture. The powder of cactus stem was mixed into the mortar, and its effect on the fresh properties and strength of the mortar was studied. The results were compared with the properties of mortars produced by mixing with a retarder sugar and a viscosity agent methyl-cellulose, which are conventional saccharide-based admixtures. Based on the test results, the cactus stem powder did not clearly show the effect as a retarding agent, whereas the flow and the air content were similar to those of the mortar mixed with methyl-cellulose. This indicated that the cactus stem powder can be used as a viscosity agent. It was found that the strength of the mortar tended to increase when the mixing ratio of the cactus stem powder was lower than 0.3%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.413-418
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• 2021

In this study, as a basic study to use recycled limestone powder as a secondary product mixture for concrete, it was found that the compressive and flexural strengths were equal to or slightly improved compared to Plain up to 10% and 20% of the RLP mixing ratio, but the strength was rather decreased at 30% mixing. As a result of the heat of hydration experiment, as the RLP mixing rate increased, the heat of hydration decreased, and the elapsed time of the maximum heat was also delayed. As a result of the drying shrinkage test, as the fine powder RLP filled the internal pores of the cement mortar, the drying shrinkage decreased as the mixing rate increased. The compressive strength, water absorption rate, and compressive strength after freezing and thawing of the concrete block mixed with RLP 20% all satisfied the group standard criteria of the Korea Concrete Industry Cooperative Federation, confirming the possibility of use as a mixed material.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.9-14
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• 2022

Most of the existing research on ferronickel slag has focused on its potential as aggregate and fine aggregate, this study was conducted focusing on the potential of ferronickel slag powder as a concrete admixture. For concrete, which fly ash, blast furnace slag, and FSP were mixed with each 10 % type the reactivity was evaluated by applying ASTM C 1260 of the United States. As a result, compared with the control group, the expansion rate of fly ash decreased by 8.43 % and that of fine blast furnace slag powder decreased by 14.46 %, while the expansion rate of ferronickel slag decreased by 49.40 %. it was confirmed that ferronickel slag can sufficiently be replaced existing supplementary cementitious admixtures such as fly ash and blast furnace slag in terms of suppressing the reactivity of aggregates. However as a result of SEM analysis, ettringites were generated, and additional research about how it affects concrete is needed.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.145-154
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• 2010

As buildings have become higher and larger, the use of high performance concrete has increased. With this increase, interest in and use of ultra fine powder admixture is also on the rise. The silica fume and BSF are the admixtures currently being used in Korea. However, silica fume is exclusively import dependent because it is not produced in Korea. In the case of BFS, it greatly improves concrete fluidity and long-term strength. But a problem exists in securing early strength. Furthermore, air-cooled slag is being discarded, buried in landfills, or used as road bed materials because of its low activation energy. Therefore, we investigated in this study the usability of nano-slag (both rapidly-chilled and air-cooled) as an alternative material to the silica fume. We conducted a physic-chemical analysis for the nano-slag powder and performed a mortar test to propose quality standards. The analysis and testing were done to find out the industrial usefulness of the BFS that has been grinded to the nano-level.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.425-430
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• 2002

The needs of the times, a cement plays an important roll in the materials field. So, in this research we would like to study on the properties of Photocatalytic Cement for waste gas reduction. The fundamental phenomena of the Photocatalytic Cement were observed by the NOx Analyzer, Bonding strength, SEM, Flow and Surface hardness(Pencil tester). As a result of this study, the Photocatalytic Cement used Photocatalytic powder, admixture and other materials can obtain its physical properties, also photocatalytic efficiency. If we have added a various experiment, we could have to develop the Photocatalytic Cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.409-414
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• 2001

The hydration of cement paste occurs when the cement is mixed with water. During the hydration, hydration heat causes the thermal stress depending on the size of concrete and the cement content. Especially in the high-strength concrete, we must give care to the concrete due to its large cement content. In this study, conduction calorimeter and concrete insulation hydration heat meter were used to investigate the hydration heat characteristics of cement and concrete. To reduce hydration heat of high-strength concrete, several types of replacement of fly-ash and blast-furnace slag powder were used in this experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.265-270
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• 2001

Nowadays, like any other areas we have asked that the concrete would get more and more properties to increase there performance. So, in this research we are intended to develop the Photocatalytic Concrete which is one of the High Performance Concrete with waste gas reduction and self-cleaning. The fundamental phenomena of the Photocatalytic Concrete were observed by the residue water-weight, SEM, flow and surface hardness(Pencil tester). As a result of this study, the Photocatalytic Concrete used Photocatalytic powder, OPC admixture and other materials can obtain its properties, also photocatalytic efficiency. Last of all, we are convinced of the Photocatalytic Concrete possibility and make an effort to develop its properties added a various study.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.575-580
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• 2002

The most recent, like any other field we have requested that the concrete would increase more a performance. So, in this research we are intended to study on the property of Photocatalytic Concrete which is one of the High Performance Concrete. The fundamental phenomena of the Photocatalytic Concrete were observed by the NOx Analyzer, Bonding strength, SEM, Flow and Surface hardness(Pencil tester). As a result of this study, the Photocatalytic Concrete used Photocatalytic powder, admixture and other materials can obtain its properties, also photocatalytic efficiency(NOx reduction). Also, we have convinced of the Photocatalytic Concrete possibility and put on a spurt to improve its properties added a various experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.620-623
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• 2004

Waste concrete powder(WCP) has been estimated with a great value-added material as by-product of waste concrete manufactured to fine and coarse aggregate for concrete, because it is able to utilized for cement clinker and concrete admixture. In the experimental results for this study, chemical composition of WCP was similar to that of cement, and specific gravity of WCPs were 2.46 and 2.48 due to internal micro-void of WCP. Final setting of paste with WCP was delayed, and flow value of mortar with WCP was tendency to reduced in comparison with that of paste and mortar with only ordinary portland cement as replacement ratio of WCP increased. Furthermore, sorptivity of mortar with WCP was increased as replacement ratio of WCP increased. Compressive strength of mortar with $15\%$ WCP was developed about 27MPa at 28days.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.624-627
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• 2004

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it according to its capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high Quality aggregate. Therefore, For solving the problems we apply to method of packaged dry combined materials for concrete using dried materials. That is to say that it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.