이 연구에서는 최근 개발된 강섬유 보강 초고성능 콘크리트(UHPSFRC)의 압축연화 거동을 실험을 통해 측정하였다. 압축 연화곡선을 안정적으로 측정하기 위해 실험체의 횡 방향 변형을 제어하여 실험을 수행하였다. 실험에 사용한 UHPFRC의 배 합은 모두 세 가지(M1, M2, M3)이며, 평균 압축강도는 각각 순서대로 131.0, 161.6, 171.5 MPa로 측정되었다. 압축강도와 섬유함유량에 따라 압축연화곡선의 거동이 다르게 나타났다.

Recently, geopolymer binder or alkali-activated binder has been enormously studied as an alternative to portland cement. However, studies on heat resistance of geopolymers are still few, whereas studies on resistances against chemical attack and carbonation, and mechanical performance of geopolymer are being investigating. This paper aims to summarize a literature review on heat resistance of gel structure in geopolymers exposed to elevated temperature.

This research investigated the influence of adding hybrid steel fiber on the direct tensile behavior of UHPFRC(Ultra high performance fiber reinforced concrete). Test results revealed that the post cracking strength and peak toughness for the Lf: 20mm Df: 0.2mm_0.5% and Lf: 22mm Df: 0.22mm_1.0% were higher than incorporate with Lf: 20mm Df: 0.2mm_1.0% and Lf: 22mm Df: 0.22mm_0.5%

In order to prevent tendon from corrosion and to provide a sufficient bond between tendon and concrete, post-tensioning grout has been used. But, the normal mixture with w/c ratio of 0.40 and add the expansive agent for 1% was not support for specification(BS EN 445) compliance. Thus, it should add some supplementary cementitious materials to improve the properties. Therefore, based on this test result, not only evaluation of bleeding, volume change, fluidity, and compressive strength, but also estimation of the shrinkage of post-tensioning grout under restrained condition remains as a pressing need.

In this paper, investigate the effect of the quality of fresh UHPC on the mixer type, it was found that the use of twin shaft mixer was fine. On the other hand, pan type mixer is required for adjustment mix proportion.

This study examines the compressive strength of cementless mortar in order to evaluate its mechanical characteristics according to the admixing of fly ash and blast furnace slag. This result showed that cementless mortar for shotcrete repair materials is profitable for using ZrSF.

The influence of mineral admixture content on the bleeding of cement-based grouts. Replacement of fly ash increased the bleeding, but the increase of the content of blast furnace slag as well as silica fume led to the reduction in the bleeding. Especially 15% replacement of silica fume showed the best performance against normal bleeding as well as channel bleeding.

A method to measure rheological properties of cementitious materials through mini slump test has been previously suggested. In this study, experiments were performed to verify that method. As the mini slump test proceeds, the spreading diameter of the material were measured by using a digital image processing technique. From the measured spreading diameter versus time curve, the rheological properties were estimated and compared to the properties measured from the viscometer.

For hybrid fiber reinforced UHPC with two kinds of steel fibers, variation of the flexural behavior with different fiber distribution characteristics was estimated by experiments, and a prediction of the flexural behavior using smeared crack model. it was found that adopting a crack bandwidth considering the fiber distribution characteristics enable to predict the fractural behavior of UHPC beam.

This research investigated the influence of adding SRA(Shrinkage reducing agent) on the direct tensile behavior of UHPFRC(Ultra high performance fiber reinforced concrete). The experimental test results revealed that the post cracking strength and strain capacity for the cement hydrated cement paste without at SRA were higher than that incorporate with 1% SRA.

This study is purposed to analyze the compressive strength development with different produce of fly ash in order to develop cementless concrete. As a results, compressive strength of cementless mortar is related to effect on compressive strength development for the type of fly ash.

In this paper, evaluated on the effect of high temperature history on the resistance to freeze-thaw of concrete. As a result, The concrete subjected to high temperature history at 50℃ and 70℃ showed good of the resistance to freezing and thawing.

This paper reviewed on the minimum strength of concrete in cold climates from the viewpoint of durability. The results show that the minimum strength to prevent early frost damage recommend to 21 MPa.

It is difficult to ensure enough workability and flowability in the fresh state of UHPC. In addition, it needs to enhance economic efficiency by reducing the usage of expensive constituents. Zirconia silica fume is an alternative material to replace the existing Silica fume. The objective of this study is to find out the effect of Zirconia silica fume dosage on viscosity of UHPC matrix

Mechanical performance of UHPC is known to be strongly influenced by placing method. In this study, in order to estimate variation in tensile behavior of hybrid fiber reinforced UHPC, two different placing methods were adopted in fabricating test specimens. Test results presents that placing method causes a noticeable variation in the tensile behavior

본 연구에서는 초고성능 시멘트 복합체(Ultra High Performance Cementitious Composites, UHPCC)의 압축강도에 미치는 강섬유 보강효과에 관한 연구를 수행하였으며, 일반 강섬유보강 콘크리트에서의 경향과 비교․검토를 실시하였다. 다양한 크기의 압축강도에 대해 UHPCC에서의 섬유보강효과에 관한 실험을 수행한 결과, 일반 섬유보강 콘크리트에서처럼 섬유보강에 따른 압축강도의 향상을 확인할 수 있었다. 실험결과는 압축강도 100MPa 이하를 대상으로 하는 일반 강섬유보강 콘크리트에 관한 기존 연구결과들과 비교분석을 실시하였다. 그 결과 모든 범위의 압축강도에 대해 압축강도에 관계없이 와 이 일정한 선형관계를 가지는 것을 규명하였으며, UHPCC를 포함하는 광범위한 압축강도의 강섬유보강 콘크리트에 대해 적용이 가능한 포괄적 섬유보강효과의 관계식을 도출하였다.