• 한국농공학회논문집
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• 제47권3호
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• pp.41-48
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• 2005

The purpose of this study is to improve the performance of jet set cement, which mixed with the mineral admixtures such as silica fume, fly ash and ground granulated blast furnace slag. First, the test of mortar according to the substitute ratio of mineral admixtures were evaluated. And then using it obtained from test results, it was conducted with experiment of mechanical, physical and permeable characteristics of concrete. Laboratory test results showed that concrete substituted for $5\%$ of silica fume didn't have an effect on prominent performance relating to compressive strength. However it was superior to concrete in case of resistance of chloride permeation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.589-592
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• 2006

The growth in concrete structure repair has prompted major efforts to develop high early strength concrete. So, we were examined fundamental properties of cement mortar using the ordinary portland cement with rapid-setting cement. The experiments were carried out to investigate the characteristics of rapid-setting cement according to the blended ratio. The containing ratio of rapid-setting cement were changed five steps (20, 30, 50, 70, 100%) and then the flow value, setting time, compressive and bond strength test of cement mortar with RSC were investigated in this study.

• 산업기술연구
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• 제19권
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• pp.163-172
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• 1999

This study is conducted on the flexural toughness and flexural fatigue test to fine the mechanical properties of steel fiber reinforced rapid-set cement concrete. Experimental investigation is examined according to fiber contents(0, 0.4, 0.7, 1.0, 1.5%), fiber aspect ratio(58, 60, 83), fiber type (hooked, crimped fiber), and cement type (normal portland & rapid-set cement). The principal results obtained through this study are as follows; toughness and fatigue resistance tend to considerably increase with fiber contents, fiber aspect ration. And hooked fiber is improved better than crimped fiber. Concrete using rapid set cement is increased strength properties compared with concrete using normal portland cement, but relative strength properties behavior and fatigue resistance show a tendency to decrease a little.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.309-312
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• 2004

The hydraulic structure of the hydroelectric power plant such as aqueduct tunnels and the drainage canal became old. Therefore, because the concrete surface of the aqueduct tunnel has received severe damage by wear-out and the crack etc the repair is demanded. This research examined the applicability of the repair mortar which mixed the fly ash and an artificial aggregate by using the very high early strength cement. As a result, good Quality repair mortar which satisfied the demand performance more than self-flow 270mm and compressive strength $50N/mm^2$ (age of 28days) adjusting of water cement ratio by using the MTX cement be able to be manufactured.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.769-772
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• 2004

Very-Early-Strength Latex-Modified Concrete(VESLMC) provides the repairing material with short curing time as well as excellent bond strength, flexural strength and impermeability against water and chloride. In 2001, VESLMC introduced in Korea and improved superior material through research and development on material properties and durability. In 2003, the field test progressed for study problems of VESLMC field application. This paper introduced equipment improvement for bridge deck repair save both repair time and labor, while producing quality VESLMC structures.

• 한국건축시공학회지
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• 제11권6호
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• pp.587-596
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• 2011

폴리머 시멘트 모르타르를 긴급공사의 보수 보강 재료로 사용할 때, 초속경시멘트와 혼입하여 사용함으로써 시멘트의 빠른 응결과 시멘트 매트릭스 내부에서 형성된 폴리머 필름의 작용이 물리적 성질과 내구성을 개선시킬 수 있다. 또한 각종 혼화재료를 혼입함으로써 매트릭스 내부 공극을 충전하여 성질을 개선시킬 수 있는데, 양생방법이 큰 영향을 미칠 수 있다. 본 연구에서는 속경성 SBR 시멘트 모르타르의 압축강도와 휨강도에 영향을 미칠 수 있는 혼화재료와 양생조건에 관하여 실험을 실시하여 그 영향성을 평가하고자 하였다. 본 연구결과, 초속경시멘트 모르타르에 SBR을 혼입함으로써 휨강도와 압축강도가 크게 개선되었으며, 여기에 메타카올린을 혼입함으로써 보다 더 강도를 증진시킬 수 있었다. 또한 양생방법에 있어서도 SBR을 사용한 경우에는 표준양생에서, SBR을 사용하지 않은 경우에는 수중양생에서 강도발현이 크게 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제22권2호
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• pp.124-132
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• 2018

본 연구는 다성분계 고유동 모르타르의 특성에 관한 연구이다. 보통 포틀랜드 시멘트(OPC), 고로슬래그 미분말(GGBFS), 칼슘설포알루미네이트(CSA) 그리고 초속경시멘트(URSC)를 혼합한 결합재이다. GGBFS는 OPC 질량에 대해 30%(P7 series), 50%(P5 series) 그리고 70%(P3 series)치환하였고, CSA와 URSC는 10%와 20%를 치환하였다. 혼화제는 폴리카르복실계를 사용하였다. 모든 배합의 물-결합재 비(w/b)는 0.35로 일정하다. 실험은 미니슬럼프, V-funnel, 압축강도 그리고 건조수축을 측정하였다. 실험결과 CSA와 URSC의 치환율이 증가하면 혼화제 사용량, V-funnel 시간 그리고 압축강도는 증가하였다. 또한 응결시간과 건조수축은 CSA와 URSC의 치환율이 증가함에 따라 감소하였다. CSA는 건조수축을 감소시키지만 URSC는 효과가 미미하다. CSA와 URSC를 혼합한 결합제는 상호보완 작용에 의해 건조수축 감소 효과가 컸다. 이는 URSC의 초기강도 향상효과와 CSA의 팽창과 장기강도 향상효과 때문이다.

• 한국구조물진단유지관리공학회 논문집
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• 제27권4호
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• pp.62-69
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• 2023

본 연구에서는 제강 슬래그 (fine steel slag aggregates, FSSAs) 혼입량에 따른 스마트 보수재료 (smart repair materials, SRMs)의 전기역학적 거동을 조사하였다. SRMs는 보수 품질을 스스로 진단하고 보수 부위의 손상을 자체적으로 감지할 수 있다. FSSAs는 SRMs에 모래 중량 대비 0% (FSSA00), 25% (FSSA25), 그리고 50% (FSSA50) 치환되어 혼입되었다. SRMs의 전기저항률은 일반적으로 압축 응력이 증가함에 따라 감소하였다: 재령 7시간 기준 FSSA25의 전기저항률은 압축 응력이 0에서 22.57 MPa로 증가함에 따라 78.16에서 63.68 kΩ-cm으로 감소하였다. FSSAs의 모래 중량 대비 치환율이 0%에서 25%로 증가함에 따라 재령 7시간 기준 응력 민감도 (stress sensitivity coefficient, SSC)는 매트릭스 내 부분적인 전도성 경로 수의 증가로 인해 0.471에서 0.828 %/MPa로 증가하였다. 하지만, 치환율이 50%까지 증가함에 따라 부분적인 전도성 경로들의 일부가 연속적인 전도성 경로로 변화하여 SSC는 0.828에서 0.649 %/MPa로 감소하였다. SRMs는 보수 부위의 전기저항률만을 측정하는 것으로 보수 품질을 진단하고 보수 부위의 추가 손상을 스스로 감지할 수 있을 뿐만 아니라 구조물의 역학적 성능을 빠르게 회복시킬 수 있을 것으로 기대한다.

• 산업기술연구
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• 제24권A호
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• pp.165-171
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• 2004

Latex modification of concrete provides the material with higher flexural strength, as well as high bond strength and reduced water permeability. However, If the thermal expansion properties of overlay concrete (latex-modified concretes) are big different from that of substrate (ordinary portland cement concrete), these would cause a big interfacial stresses and result in premature failure. Therefore, the purposes of this study were to investigate thermal expansion characteristics of latex-modified concrete with cement types. The result of thermal expansion showed the coefficient of thermal expansion of concretes increased with latex inclusion. The coefficient of thermal expansion of RSLMC was a little smaller than that of LMC, which might be due to the finer cement grain, compacter internal, and stiffer properties of concrete. However, the coefficients of LMC and RSLMC were quite similar to that of ordinary cement concrete. Thus, this would not cause an interfacial stresses and will enable to ensure long-term performance of concrete bridge deck overlays.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.269-272
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• 2004

After concrete casts, temperature decent and shrinkage bring volume changes of concrete pavement. Microcracking and cracking in concrete pavement are caused by these volume changes. As a result, durability of concrete pavement is deteriorated. Recently, Very-Early Strength Latex Modified concrete(below:VESLMC) from the beginning of High-Way is used as urgent repair material for bridge deck. The advantage of VESLMC is that compressive and flexural strength at 3 hours age are 4.5MPa and 21MPa respectively. It allows the traffic to open in 3 hours. But, this material has the problem which is early-age shrinkage cracking caused by water self-dissipation with rapid hydration reaction and water evaporation with body dry. Unfortunately, until now, the research about early-age shrinkage of VESLMC leaves something to be desired. Therefore, the purpose of this study is to present the early-age shrinkage of VESLMC respect to latex contents and shrinkage ratio to maximum length change that can help field engineers' skill. Latex contents of 0, 5, 10, 15, $20\%$ in standard of same workability in VESLMC are selected by experimental variables. After initial set, shrinkage value was measured with 10mm LVDT for 3 days. The results of maximum shrinkage ratio were 0.019, 0.017, 0.023, $0.027\%$ respectively.