• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1121-1126
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• 2000

The purpose of this study is to clarify chemical resistance of polymer-cement slurry coated reinforcing bars. Polymer cement slurry coated reinforcing bars were showed the good state to the bending resistance, impact resistance, adhesive strength, but exact data of the chemical resistance do not exist. Through the experimental, it is to certify chemical resistance of polymer cement slurry coated reinforcing bars. In this study, polymer cement slurry coated reinforcing bars are prepared with two types of polymer, polymer-cement ratios of 50%, 100%, 150%, coating thickness, curing periods of 3, 7, 28days, and tested for chemical resistance as KS(Korea Standard). From the test results, chemical resistance of polymer cement slurry coated reinforcing bars used by acrylic and St/BA emulsion were showed excellent without concerned polymer-cement ratios, curing period except for 1% aqueous solution $H_2SO_4$. But polymer cement coated reinforcing bar used by acrylic emulsion is inferior to aqueous solution NaOH.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.117-122
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• 2001

Recently, epoxy-coated re-bar used to the structure partly and put to practical use step, but not economical and appeared to the defect of deterioration of long term bond strength between concrete. The method for complement the defect of epoxy coated re-bar, study of polymer cement slurry coated re-bar started and basic properties appeared to excellent, but study of bond properties embedded in concrete specimens insufficient until now. This study attempts to examination of using possibility for bond strength of polymer cement slurry coated re-bar between concrete specimens compare to ACI Code and KS Code through pull-out test of 15cm$\times$15cm$\times$15cm specimens with polymer cement slurry coated re-bar as polymer cement ratio 50%, 100%, 150%, coating thickness 250${\mu}{\textrm}{m}$, 440${\mu}{\textrm}{m}$ and curing age. In the results of this study, the bond strength of polymer cement slurry coated re-bar compare to plain re-bar, epoxy coated re-bar decreased St/BA-modified polymer cement slurry coated re-bar, but bond strength of PA-modified polymer cement slurry coated re-bar appeared to excellent results. The bond properties of polymer cement slurry coated re-bar between concrete will be obtain more precise results according to compressive strength change of concrete and re-bar diameter size.

• Geomechanics and Engineering
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• 제29권3호
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• pp.237-247
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• 2022

To investigate the curing temperature effect on the engineering properties of ground granulated blast furnace slag-cement bentonite (GGBS-CB) slurry for cutoff walls, the laboratory experiments including the setting time, unconfined compressive strength, and permeability tests were carried out. The mixing procedure for GGBS-CB slurry was as follows: (1) montmorillonite-based bentonite slurry was first fabricated and hydrated for four hours, and (2) cement or GGBS with cement was added to the bentonite slurry. The dosage range of GGBS was from 0 to 90 % of cement by mass fraction. The GGBS-CB slurry specimens were cured and stored in environmental chamber at temperature of 14±1, 21±1, 28±1℃ and humidity of 95±2% until target days. The highest average temperature of three seasons in South Korea was selected and used for the tests. The experimental results indicated that in early age (less than 28 days) of curing the engineering properties of GGBS-CB slurry were primarily affected by the curing temperature, whereas the replacement ratio of GGBS became a main factor to determine the properties of the slurry as the curing time increased.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.201-206
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• 2002

The purpose of this study is to improve the anti-corrosive properties of coated reinforcing bar using polymer cement slurry. Poymer cement slurry are prepared with three types of polymer dispersions and corrosion inhibiting admixture. And tested for corrosion accelerating tests such as immersion in NaCl 10% solution NaCl 10% solution spray, high temperature and pressure steam in condition of 8cycles, carbonation before and after, penetration of NaCl solution. From the test results, it is concluded that the anti-corrosive properties are considerably improved by coating using polymer cement slurry at surface of reinforcing bar. And this trend is marked by adding of corrosion inhibiting admixture. The difference of the anti-corrosive properties is hardly recognized according to types of polymer dispersions. The anti-corrosive properties of coated reinforcing bar using polymer foment slurry are improved to a great extent compared to those of plain reinforcing bar accordiy to increasing content of chloride ion in cement concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.69-72
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• 1999

In this study, we blended 2 grades of ultra fine cement using the results of previous stud. And the cement slurry was produced by water each water/cement ratio. The slurries were observed hydration phenomena during 28 days with SEM, XRD and DSC. The specimen made by slurry were evaluated with the hardened properties such as compressive strength, flexural strength length change and water absorption. And were tested the adhesive strength of specimen made by injecting the slurry between mortar bars.

• KCI Concrete Journal
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• 제13권2호
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• pp.42-48
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• 2001

The bend resistance of coated reinforcing bar is greatly influenced by both the adhesion strength between bar and coating materials, and the followed transformation of coating material as bars bend. Especially, tearing state or partial microscopic cracks are predicted on the inside and outside of bending angle, because tensile strength and elongation of polymer film are very different according to types of polymer dispersions in bar coating, and these damaged parts are rapidly corroded by penetration of corrosive factors. In this study, polymer cement slurry coated reinforcing bars with various polymer dispersions are prepared by following combined conditions, polymer-cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 28days. Then the specimens are tested for working life and bend resistance at bending angles $90^{\circ}$, $135^{\circ}$and $180^{\circ}$ to observe the microscopic damage effect as the bars bend. Also, epoxy-coated reinforcing bars for control experiment were used with 250$\mu$m of coating thickness. The tensile strength for polymer films is performed. From the test results, the working life of the polymer cement slurry is within 90 seconds. Among four types of polymer dispersion, polymer cement slurry coated reinforcing bar using St/BA-1 emulsion has the excellent bend resistance, which is remarkably improved than that of epoxy-coated reinforcing bar. And the bend resistance is more related to elongation than tensile strength of polymer film. Polymer cement slurry with a polymer-cement ratio of 100%, a coating thickness of $450\mu$m and one coating using St/BA emulsion is selected as a most suitable coating material for coated reinforcing bar.

• 한국건축시공학회지
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• 제9권5호
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• pp.71-77
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• 2009

시멘트 혼화용 폴리머 디스퍼션은 시멘트 모르타르 및 콘크리트 내부에서 폴리머 필림을 형성하여 각종 역학적성 질 및 내구성을 향상시킨다. 본 연구는 3종류의 폴리머 디스퍼션을 폴리머 시멘트비 0, 5, 10, 20%로 변환한 폴리머 시멘트 모르타르를 제작, 투수시험을 실시하여 투수성능을 실험하였으며, 더욱이 폴리머 시멘트 슬러리를 폴리머 시멘트 모르타르 표면에 도포하여 방수성능의 개선효과를 평가하였다. 또한 보통시멘트 콘크리트 표면에 폴리머 시멘트 슬러리를 도포하여 시멘트 콘크리트와 폴리머 시멘트 슬러리의 건조수축을 측정하였다. 그리고 기본적인 역학적 성상인 휨강도와 압축강도를 측정하여 보통 시멘트 모르타르와 비교 검토하였다. 연구결과, 폴리머 시멘트 모르타르는 보통 시멘트 모르타르에 비해 방수성능과 강도가 크게 개선되었으며, 폴리머 시멘트 슬러리의 건조수축은 시멘트 콘크리트에 비해 4-5배 크게 나타났다. 또한 향후 건조수축에 따른 접착성능의 영향성에 대한 연구가 진행되어야 할 것이다.

• 한국건축시공학회지
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• 제2권3호
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• pp.131-138
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• 2002

The objective of the study is to examine the characteristic correlations between reinforcing carbon fiber and interfacial adhesion agent since the interfacial adhesion strength between reinforcing carbon fiber and matrices is believed to be an essential element influencing the physical properties in carbon fiber reinforced cement composite using slurry method. The integrity of interfacial adhesion between reinforcing fiber and cement not only affects the quality of fiber reinforced cement composite but also influences to a large degree the physical properties of the cement composite when producing carbon fiber reinforced cement composite using slurry method. Having analyzed the physical properties 1.e., water content, tensile strength, flexural strength and flexural toughness of carbon fiber reinforced cement composite specimens, C-PAM(cation polyacrylamide) was determined to be an optimum interfacial adhesion agent. The study has also demonstrated that interfacial adhesion strength varies largely on the content and type of the reinforcing fiber. Judging from magnified view of the tensile shear cross-section using VMS(video microscope system), interfacial adhesion strength between reinforcing fiber and matrices is affected by the type of interfacial adhesion agent. According to the result of the experiments, C-PAM was determined to be an ideal interfacial adhesion agent when using carbon fiber in producing carbon fiber reinforced cement composite with the optimum content of carbon fiber being established.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.343-348
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• 2000

The purpose of this study is to clarify properties adhesive strength of polymer-cement slurry for coated reinforcing bars. The epoxy coating material is superior to performance of anti-corrosion but lately age adhesive strength between concrete raise to structural problems. However, polymer dispersion with excellent performance of elasticity and adhesion can solve this problems. From the test results. adhesion of steel with polymer cement slurry using St/BA emulsion is show excellent without concerned coating thickness, and polymer cement slurry using St/BA emulsion is show adhesion in tension 1.2~2.2MPa at polymer cement ratio 50% of more.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.215-220
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• 2002

Epoxy-coated re-bar was partly used to the structures and put to practical use, but were not economical and appeared to have defects such as the diminishing of long term bond strength between concrete. The study of polymer cement slurry coated re-bar was started in order to complement the defect of epoxy coated re-bar, and ever since the basic properties appeared to be excellent. But, study of bond properties embedded in concrete specimens was insufficient until now. This study attempts to examine the possibility of improving the bond strength of polymer cement slurry coated re-bar between concrete specimens in accordance with ACI Code and KS Code through pull-out test of 150mm$\times$150mm$\times$150mm substrates with polymer cement slurry coated re-bar having polymer cement ratios of 50%, 75% and 100%, coating thickness 250${\mu}{\textrm}{m}$, 450 ${\mu}{\textrm}{m}$ and with curing ages of 3, 7 and 28 days. High strength concrete was designed having a compressive strength of 500kgf/cm2 as specified. Practical bond length ranges of 55 and 85mm were applied to each of specimen. The bond strength of polymer cement slurry coated re-bar using St/BA-1 and St/BA-2 was compared to that of plain re-bar. The results of this study showed that the bond strength of 55mm bond length was much higher than that of 85mm bond length.