• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.853-858
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• 2000

According to the results of this research, Production of Fold Mortar Permanent - Form was found to be possible by Mortar. Th FP-Form (Fold Permanent-Form) mortar had compress strength 580kgf/$\textrm{cm}^2$. FP-Form model was made by the result of the first research. There was no minute-crack on beam form and the outer surface of form was very smooth, and those qualities it were made possible hand-mad by experiment. This study is about bond strength progress of FP-Form that developed for the form work rationalization and systematization. The result of this study follows; (1) Fluidity and strength development of mortar which used for FP-Form are satisfied (2) After study on getting good bond strength progress, inside-uneven type presents the better suitableness, and wire netting V-type presents the better shear strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.171-172
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• 2017

In order to meet the high performance of the concrete, the viscosity increases with water binder ratio and amount of powder. because of these problems, we use high performance water reducing agent and low viscosity water reducing agent, but side effects may occur when using large amount of water reducing agent. Therefore, in this research, in order to increase the viscosity, I would like to analyze the change in viscosity and flow characteristics of paste by utilizing fly ash and lung limestone which are generally thrown away without using high performance water reducing agent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.187-188
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• 2018

For the concrete construction, finishing process is inevitable for crack control and improving permeability. The finishing process is closely related with setting time, but currently, the timing of the finishing process is not managed with scientifically but feeling of the workers. In this research, therefore, by comparing with the setting time measured with penetrating method, the feasibility of durometer for measuring setting time was analyzed. As a result, there was a high relationship between setting time measured with penetration method and durometer. Therefore, it is expected that using durometer can be a good solution for assessing setting time for finishing process.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.413-416
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• 2005

The super early hardening cement is widely used for reducing construction period. But there are some problems with handling the cement because the loss of workability is so big to control. In this study, the fluidity properties of super early hardening cement paste was evaluated at early age of hydration by using gel-time determination method. 4 types of set controlling agent were selected and combinations of them were used for gel-time test. As a result, the gel-time of super early hardening cement paste was extended up to 20 minutes by using the combinations of several types set controlling agent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.110-111
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• 2019

Concrete with high thixotropy has a lower plastic viscosity when pour in, thus demonstrating fluidity, and After poured, the viscosity can be restored again to ensure stable progress without additional liquidity and material separation. Therefore, in this study, a basic study of thixotropy of concrete was proceeded through cross-linked bond of PVA and Borax. Therefore, it is judgment that the higher the concentration of boron solutions, the higher the strength of the interconnections between PVA and boron.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.721-724
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• 2006

In this study, particle size distribution of cement powder system were adjusted using the blast furnace slag powder, Blaine $2250cm^2/g\;and\;8300cm^2/g$, which easy to adjust particle size distribution to examine how particle size distribution of the binder has an effect on rheological properties of the cement paste. In addition, the relationship between n-value of Rosin-Rammler function and plastic viscosity were discussed. All measured flow curves represented thixotropy behavior and the hysteresis area was smaller for the more added coarse particle. When the combination was based on a ratio of $20{\sim}25vol%$ fine particles, $30{\sim}40vol%$ OPC and $40{\sim}45vol%$ coarse particles of the total volume, a high fluidity and low yield strength was achieved.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.149-150
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• 2023

Although concrete is a material widely used in the construction industry, it is very vulnerable to cracking and has a disadvantage in that durability deteriorates when cracks occur. When cracks occur, harmful factors are introduced through the micro-cracks of the structure, reducing durability. Therefore, in this study, as part of a study to alleviate the problems of maintenance and durability deterioration due to cracks in concrete structures, the mechanical properties of self-healing mortar according to the size of the capsule made of cement material were reviewed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.305-306
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• 2023

Recently, as the radioactive waste disposal facility becomes scarce, the importance of efficient disposal of waste from nuclear power plants is increasing. This study was conducted to utilize radioactive waste concrete powder as solidifying agent for radioactive waste treatment. Paste with an age of more than one year was used with a disk mill to have a particle size of 150㎛ or less, and treated at temperatures of 500℃, 600℃ and 700℃ for 2 hours. In order to simulate the radioactive cement powder, aqueous solutions of Di-water, CsCl 1M, SrCl₂ 1M and CoCl₂ 1M were used as blending water at W/C 0.7 and to improve fluidity, polycarboxylate type superplasticizer was used at 0.4 wt.% based on the weight of recycled cement paste powder. Characterisation was carried out using vicat method, strength and density.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.37-41
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• 2008

According to the recent rapidly increasing that construction works are gradually Manhattanized mainly the grand scaled residential buildings, the foundation of the building that is related to safety is increasing for building as a grand scaled mat concrete. Because mat concrete can not be simultaneously placing of concrete in a great quantity due to the circumstance at the field, the inequal deformation of the tensile stress that according to the time lag of hydration heat between the upper layer and the lower layer is affecting as a cause that is the possibility of crack occurrence by increasing. Accordingly, this research checked the efficiency of super retard concrete in applying real structures, and we implemented the preparatory experiment to settle up the inequal deformation of the tensile stress substantially that is according to the time lag of placement between the upper layer and the lower layer by controlling the setting time using the super retarding agent. As the result of test, the more target of delay time lengthened, the more fluidity increased and air content indicated a little differences. There was from 2 to 10 hours between the standard curing and the outside curing at the setting time and in case of calculating the rate of mixing at real structure is required that mix promotion, increasing the amount of mixing, by setting up the curing temperature. The super retard concrete showed the result that in compressive strength, early-age strength was smaller than normal concrete whereas it was same or more figures from at the aging 28days because of the super retarding agent.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.409-412
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• 2008

There are many methods to improve the performance of concrete. Especially, admixture materials used in concrete as the replacement materials of cement, could fluidity, strength and durability of concrete. So recently, the terminology "High-Performance Concrete(HPC)" has been introduced into the construction industry. Most hige-performance concrete have a high cementitious content and a low water-cementitious material ratio. The proportions of the individual constituent vary depending on lacal preferences and local materials. Therefore, many trial batches are usually necessary before a successful mix is developed. The objective of this experiments is to investigate the fundamental properties of high performance concrete based binary cimentitious materials such as ordinary portland cement and ground granulated blast furnace slag. In this study, Use granulated blast furnace slag (30%, 45%, 60%) and water cementitious content (26%, 30%, 34%) take the gauge of capacity that strength, carbonation and XRD, X-Ray Diffraction test