爆裂制御用 纖維를 混入한 高强度콘크리트의 養條生件에 따른 收縮特性

다국어 초록 (Multilingual Abstract)

Shrinkage forms of concretes in a sate without exterior force include autogenous shrinkage, drying shrinkage) and carbonated shrinkage that is by carbonation, among which it is drying shrinkage that mostly exercises an effect on volume change of ordinary concrete. Besides, recently high performance and super high performance concretes have appeared, it has widely known that a volume change of concrete according to autogenous shrinkage exercises an effect on dynamic behaviour of concrete structure and many studies are conducting actively for the issue.
Such concrete shrinkage induces a volume change when a moisture is changed. and such change of moisture is dependent on conditions of evaporation of concrete surface and drying in the surrounding. For a skyscraper, the dimensions of sub materials are quite large to secure structure safety even though a high strength concrete is utilized, so that it may lead to different conditions of humidity in inner part of sub materials, drying, and concrete surface.
Various evaluation methods of shrinkage are suggested in Korea, but it is done in general according to KS F 2424 『Testing method for length changes of mortar and concrete』. But a high strength concrete generally applied in skyscraper produces a little of dry shrinkage pursuant to moisture evaporation because it has lower W/C(or W/B), unit quantity, and higher watertightness than an ordinary concrete, for which many researchers point out limitations of traditional evaluation methods and modeling of shrinkage or dry shrinkage and are suggesting the evaluation methods and modeling of shrinkage in which various conditions of high strength concrete are taken into account. The study was aimed to evaluate shrinkage characteristics of high strength concrete according to curing conditions by considering various dynamic properties and the sub material conditions in a skyscraper. Elasticity modules and shrinkages of high strength concretes with 80～100MPa, which are usually applied in skyscrapers in Korea, were evaluated, so that effect of polymix fiber mixing on the dynamic characteristics was examined to secure a fireproof. And a comparison with ACI Model Code, generally applied in structure designs in Korea, was carried out to secure a reliability of the study results.

This thesis consists of as follows.

In chapter 1, the necessity and purpose of this study is described.
In chapter 2, a part of theoretical consideration describes major factors that affect shrinkage mechanism
In chapter 3, Shrinkage characteristics of the high strength concrete mixed with spalling control fiber was evaluated, whose results were compared and analyzed with ACI Model Code.
In chapter 4, the overall conclusion of this study is mentioned.

The result of this study can be summarized as follows.

◎ Shrinkage Properties According to curing Condition of the High Strength Concrete Mixed with Spalling Control Fiber

(1) The fiber utilized in the study was not affected significantly in the conditions of not hardened properties. It has shown that in the dynamic characteristics of high strength concrete, a high compressive strength and elasticity module were appeared at early-age and long-term age was lower appeared than early-age.
(2) Elasticity coefficients according to compressive strengths were evaluated somewhat higher than CEB-FIP and KCI Model, but it has shown a trend similar with ACI and EC Model Code.
(3) Specimens mixed with fiber produced a reduction effect of shrinkage independent of the evaporation conditions of Unsealed and Sealed. And under the conditions of Unsealed, as characteristics of dry shrinkage of specimen, a shrinkage was decreased as compressive strength was increased, but under the conditions of Sealed, as characteristics of autogenous shrinkage or autogenous dry of specimen, shrinkage amount was increased as compressive strength was increased.
(4) Results of comparison with ACI Model Code show that the predicted are higher than the measured independent of the surface evaporation conditions and fiber mixing, through which a corrected prediction formula is suggested, that may have a sufficient reliability.

목차 (Table of Contents)

• 제 1 장 서 론 1
• 1.1 연구의 배경 및 필요성 1
• 1.2 연구의 목적 2
• 1.3 연구의 내용 및 범위 4
• 제 2 장 콘크리트 수분과 수축에 미치는 영향요인 분석 6
• 2.1 콘크리트와 관련한 물의 성질 6
• 2.2 시멘트 수화물의 미세구조 8
• 2.3 콘크리트의 수축 메커니즘 10
• 2.4 상대습도와 수축과의 관계 16
• 제 3 장 폭렬제어용 섬유를 혼입한 고강도콘크리트의 양생조건에 따른 수축특성 평가를 위한 실험적 연구 19
• 3.1 실험계획 및 방법 19
• 3.1.1 실험계획 19
• 3.1.2 사용재료 20
• 3.1.3 콘크리트배합 22
• 3.1.4 콘크리트 비빔 및 시험체 제작 23
• 3.1.5 시험방법 23
• 3.2 실험결과 및 고찰 27
• 3.2.1 굳지 않은 성상 평가 27
• 3.2.2 압축강도 및 탄성계수 평가 28
• 3.2.3 건조조건에 따른 수축평가 29
• 3.3 결 언 41
• 제 4 장 결 론 42
• 참 고 문 헌 44
• ABSTRACT 48