• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2003.11a
• /
• pp.69-72
• /
• 2003

This study is intended to investigate the fundamental properties of concrete which AE water reducing agent for reduction of bleeding is used, and the properties of bleeding reduction. According to the results, when the adding ratio of AE water reducing agent for reduction of bleeding increases, a range of normal fluidity and aimed air content arc satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 60 min. When, AE water reducing agent for reduction of bleeding is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for reduction of bleeding. Synthetically, it proves that AE water reducing agent for reduction of bleeding satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2003.05a
• /
• pp.69-72
• /
• 2003

This study is intended to investigate the fundamental properties of concrete which AE water reducing agent for reduction of bleeding is used, and the properties of bleeding reduction. According to the results, when the adding ratio of AE water reducing agent for reduction of bleeding increases, a range of normal fluidity and aimed air content are satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 60 min. When. AE water reducing agent for reduction of bleeding is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for reduction of bleeding. Synthetically, it proves that AE water reducing agent for reduction of bleeding satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Journal of the Korea Institute of Building Construction
• /
• v.4 no.1
• /
• pp.133-140
• /
• 2004

This study is intended to investigate the properties of bleeding reduction of concrete using AE water reducing agent for the type of bleeding reduction with the replacement admixture. According to the results, when the adding ratio of AE water reducing agent for the type of bleeding reduction increases, a range of normal fluidity and aimed air content are satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 50 min. When AE oater reducing agent for the type of bleeding reduction is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for the type of bleeding reduction. Synthetically, it proves that AE water reducing agent for the type of bleeding reduction satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.232-328
• /
• 2001

This paper investigates the influences of water content and viscosity agent on the bleeding of concrete. According to test results, fluidity shows decline tendency as water content decreases, and dosage of viscosity agent increases. PEO viscosity agent does not affect the air contents while, MC viscosity agent causes air loss. As for bleeding, bleeding decreases with decrease of water content. As dosage of viscosity agent increase, bleeding decreases, regardless of viscosity kinds. It is thought that viscosity agents have the favorable effect of reducing bleeding, if fluidity and air loss are improved.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.75-78
• /
• 2003

This study is to investigate the probability to develop the AE Water-reducing agent which can decrease the bleeding by mixing melamine type super-plasticizer(SP) and methyl cellulose(MC) viscosity agent. According to the result, as the mixing ratio of melamine type SP and MC viscosity agent increases, the bleeding is reduced due to a increase of the air content. When the mixing ratio of melamine type SP and MC viscosity agent is 1:2 and 1;3 at the water content of 165kg/$m^3$ and 175kg/$m^3$ respectively, slump and air content are satisfied and bleeding is reduced to some extent, so this is determined as the mixing ratio of AE water reducing agent for reduction of bleeding. It is prove that the developed AE water reducing agent for reduction of bleeding can reduce the amount of bleeding and prohibit the plastic shrinkage crack by slowing down the bleeding speed. Compressive strength of hardened concrete does not make any difference in comparison with plain concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.339-342
• /
• 2003

This study is intended to investigate the influence of chemical admixture on bleeding of concrete. According to the results, the amount of bleeding with elapse of time does not make much difference in the case of naphthalene type water reducing agent(RN), Naphthalene type high performance water reducing agent(HN) and Melamine type high performance water reducing agent(HM), but it is largest in the case of Polycarbonic acid type high performance water reducing agent(HP). Bleeding speed also is highest in the case of HP in comparison with other chemical admixture. This prove that high performance water reducing agent like HP has little effect on fluidity of concrete, but influences the amount of bleeding more greatly, instead. As properties of hardened concrete, compressive strength makes no difference in the case of RN, HN and HM, but on the other hand, it increases in the case of HP due to a decrease of air content and the large amount of bleeding.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.265-268
• /
• 2002

This study is focused on the influence of mixture and construction factor on bleeding amount of concrete According to the results, Amount of bleeding with mixture factor increases with increase of water contents and W/C. Amount of bleeding with construction factors is larger in the case of placing height of 1m than in the case of placing height of 0 and 0.5m. Amount of bleeding is larger at the temperature of 20℃ than at the temperature of 35℃ and 5℃, and increases in order of vibration compacting, standard lamping and non tamping. Therefore, to reduce bleeding, it is thought that it is profitable to reduce water content within the range that fluidity and workability don't go bad, to lower the placing height and not to do compacting too much.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.321-326
• /
• 1997

Recently, High Range Water Reducing Admixture be used increasingly in other to improve the demanded properties (fluidity, strength, durability etc.) and workability in concrete. These kinds of agent govern quality characteristics (air content, setting time, slump, bleeding etc) by the difference of its dispersing mechanism and performance in manufacture of flowed concrete. Accordingly, in this study, for the purpose of high quality construction in site, the comparative experiment of dispersing ability due to commercially available three types of agent were carried out in paste, mortar and concrete using tow types of cement (I, V). In conclusion, the bleeding reduction by the dispersing ability of agents was verified in the fresh properties of flowed concrete with sea water resistance.

• Korean Journal of Health Education and Promotion
• /
• v.11 no.1
• /
• pp.85-94
• /
• 1994

The purpose of this study is to provide a guide for selection of oral hygiene devices for nations and establishing valid indication of recently popularized water jet. The author has divided 36 persons into general, orthodontic, periodontal patients according to their oral hygiene state, and then evaluated the degree or decrease in plaque indices and gingival bleeding indices. The obtained results were as follows. 1. When both manual toothbrush and water jet were used together by three kind of patients, significant decreases in plaque index were observed in all patients, after 4 weeks compared with ordinary toothbrushing only(p<0.05). 2. When both oral hygiene devices were used together by three kind of patients, significant decreases in gingival bleeding index were observed in all patients after 4 weeks compared with ordinary toothbrushing only(p<0.05). 3. Singificant differences of the average gingival bleeding index & plaque index among three kind of patients were observed(p<0.05). 4. Therefore, it is concluded that for effective oral hygiene care. water jet can be recommendable to general patients, especially to orthodontic or periodontal patients.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.512-520
• /
• 2020

Recently, the applications of the standing column well (SCW) ground heat exchanger (GHX) have increased significantly in Korea as a heat transfer mechanism of ground source heat pump systems (GSHP) because of its high heat capacity and efficiency. Among the various design and operating parameters, bleeding was found to be the most important parameter for improving the thermal performance, such as ground thermal conductivity and borehole thermal resistance. In this study, a bleeding analysis model was developed using the thermal response test data, and the effects of bleeding rates and bleeding locations on the thermal performance of anSCW were investigated. The results show that, when the ground water flows into the top of anSCW, the time variation of circulating water temperature decreased with increasing bleeding rate, and the ground thermal conductivity increases by as much as 179% with a 30% bleeding rate. When the ground water flows into the bottom of the SCW, the circulating water temperatures become almost constant after the increase in the beginning time because the circulating water exchanges heat with the ground structure before mixing with the ground water at the bottom.