변형경화형 시멘트 복합체로 휨 보강된 콘크리트 보의 구조성능 = Flexural Performance of Plain Concrete Prisms with a Layer of Expansive Strain-hardening Cement-based Composite(SHCC) prepared with Hybrid Polyethylene(PE) and Steel Fiber

다국어 초록 (Multilingual Abstract)

Diversified repair/reinforcing materials and methods are developed and put to practical application for ensuring durability recovery of steel concrete structures and long service life of architectures in preparation for durability deterioration caused by environmental and physical factors. However, in case of existing repair, reinforcing materials, it has a drawback of increased maintenance cost and in terms of durability, it is reported that it has little difference with existing concrete.
Recently, cement composite reinforced with single fiber, of which crack controlling performance is excellent, that improved those problems of repair, reinforcing materials of cement-based composite was developed. This material of a new concept is called as SHCC composite or HPFRCC (High Performance Fiber Reinforced Cement Composites) and as SHCC is excellent for its flexural crack controlling performance, strain capacity and stress redistribution by widely distributing micro cracks by single fiber function of cement matrix inside, its utilization as repair, reinforcing materials of concrete structures is being attempted in a diversified way.
As materials used for the study, synthetic fiber of SF (steel fiber) and PE (Polyethylene) was used as reinforced fiber of cement composite by hybridization in order to enhance strain hardening and strength features of SHCC reinforced with single fiber only and in order to control shrinkage of SHCC, a rich mix, expansive SHCC replacing 10% of cement volume by expansive admixture of CSA line and normal SHCC were produced.
Under this background, in plain concrete beam flexural strengthened with mechanical features as a result of expansion admixture replacement of SHCC mixed with PE and SF and expansive SHCC, this study intends to review an applicability of expansive and normal SHCC as repair, reinforcing materials by evaluating flexural and crack controlling performance of concrete beam with taking SHCC compressive strength and reinforcing thickness as variables.
Beam with size of 100x100x400mm was manufactured by placing expansive SHCC and normal SHCC with thickness of 30 and 40mm after having manufactured plain beam of 30MPa class. As loading condition, 4 point loading was applied with velocity of 0.75mm/min through displacement control method using UTM of 200kN capacity.
As a result of material test, as replacing 10% of cement by expansive admixture, initial hardened shrinkage of SHCC of 30, 70 and 100MPa class was observed to be decreased and in particular, in 70MPa class SHCC, as a result of replacing 10% of cement by expansive admixture, excellent features in terms of compressive strength, flexural strength and tensile strength was represented.
As a test result of concrete beam flexural strengthened with SHCC, as compressive strength of SHCC, a flexural reinforcement, is increased from 30MPa to 70Mpa, flexural strength of concrete beam reinforced with SHCC was increased by app. 30% but flexural strength of concrete beam strengthened with SHCC of 70 and 100MPa class did not show any difference. As strengthened thickness/depth of beam are increased, flexural performance and crack distribution performance of all the test pieces were improved and it is considered that this phenomenon is attributable to strain hardening features of SHCC that is flexural strengthened to the tensile side. At the time of strengthening SHCC to the tensile side of concrete beam, it is judged that ductility increase by durability increase and cracking damage control could be expected.

목차 (Table of Contents)

• 제 1 장 서 론 1
• 1.1 연구배경 1
• 1.2 연구목적 및 범위 4
• 1.3 논문구성 4
• 제 2 장 기존 연구 및 동향 6
• 2.1 국내외 변형 경화형 시멘트복합체에 관한 연구 6
• 2.2 변형 경화형 시멘트 복합체 적용 사례 연구 8
• 2.3 시멘트 복합체로 휨 보강된 보의 적용 사례 연구 10
• 제 3 장 변형 경화형 시멘트복합체의 특성 12
• 3.1 사용재료 12
• 3.1.1 팽창재 12
• 3.1.2 섬유 12
• 3.1.3 기타 13
• 3.2 시험계획 및 제작 14
• 3.3 시험방법 17
• 3.4 재료시험 결과 19
• 3.4.1 수축 특성 19
• 3.4.2 압축 특성 20
• 3.4.3 직접 인장특성 20
• 3.4.4 휨 특성 21
• 3.5 소결 21
• 제 4 장 SHCC로 휨 보강된 콘크리트 보의 보강성능 23
• 4.1 실험계획 및 제작 23
• 4.2 실험방법 25
• 4.3 실험경과 및 분석 26
• 4.3.1 균열진전 및 최종파괴양상 26
• 4.3.2 휨응력-처짐 관계 곡선 30
• 4.3.3 균열거동 특성 34
• 4.3.4 휨 보강재와 모재 콘크리트의 계면특성 35
• 4.4 SHCC 보강에 따른 성능평가 38
• 4.4.1 SHCC 기여도 평가 38
• 4.4.2 SHCC로 휨 보강된 단면의 이상화 39
• 4.4.3 SHCC 보강에 따른 휨내력 산정 41
• 4.4.4 SHCC 보강에 따른 보강두께 산정 44
• 4.5 소결 45
• 제 5 장 결 론 46
• 참 고 문 헌 48
• ABSTRACT 51