Name: concrete workability with the vebe test
Uploaded: 2024-11-07T14:48:28.000Z
Duration: 1 min 22 s
Channel: JoVE

Vebe 테스트는 콘크리트에서 작업성을 확인하기 위해 수행되며, 가급적이면 건조 혼합물에 적합합니다.
테스트 장치는 직경이 9.5인치, 높이가 8인치인 원통형 챔버, 슬럼프 원뿔 및 투명한 디스크 모양의 라이더로 구성됩니다. 이 전체 설정은 진동 테이블에 배치됩니다.
실린더에 배치된 표준 슬럼프 콘은 표준 방식으로 콘크리트로 채워지고 슬럼프 콘은 제거되어 새 콘크리트는 잘린 원뿔 모양으로 남습니다.
그런 다음, 장치에 의해지지되는 6 파운드의 투명한 디스크 모양의 라이더가 콘크리트 원뿔 위에 놓입니다.
초당 50 사이클로 작동하는 진동 테이블은 수직 이동을 유도하여 실린더의 콘크리트 압축을 용이하게 합니다.
실린더의 콘크리트는 투명한 라이더가 완전히 가려질 때 완전히 압축된 것으로 간주되어 콘크리트 표면에 눈에 띄는 공극이 없음을 나타냅니다.
전체 콘크리트 다짐에 필요한 에너지로 표시되는 혼합물의 작업성은 베베 초(Vebe seconds)로 측정되며, 이는 콘크리트가 슬럼프 원뿔 모양에서 원통형으로 전환되는 기간입니다.

vebe 테스트

Vebe 테스트는 콘크리트의 작업성을 측정하는 데 사용되는 방법으로, 특히 건식 콘크리트 혼합물에 효과적입니다. 이 테스트는 원통형 챔버, 표준 슬럼프 콘, 투명한 원반형 라이더를 포함한 특정 장치를 사용하며, 모두 진동 테이블에 장착됩니다. 원통형 챔버의 치수는 직경 24.13cm, 높이 20.32cm입니다.


 테스트를 실시하기 위해 콘크리트를 슬럼프 콘에 넣습니다. 콘크리트는 층으로 채워지고 표준 방식으로 압축됩니다. 채워지면 슬럼프 콘을 제거하여 원통 내부에 절두 원뿔 모양의 콘크리트를 남깁니다. 그런 다음 장치로 지지되는 2.72kg의 투명한 원반형 라이더를 콘크리트 콘 위에 놓습니다.


 그런 다음 진동 테이블을 50Hz의 주파수로 작동시켜 콘크리트를 압축하는 수직 운동을 유도합니다. 다짐 완료는 투명한 라이더가 콘크리트에 완전히 가려져 콘크리트 표면에 눈에 보이는 공극이 없음을 나타낼 때 결정됩니다.


 콘크리트의 작업성은 진동 하에서 콘크리트가 초기 슬럼프 콘 모양에서 완전히 다진 원통 모양으로 전환되는 데 걸리는 시간인 Vebe 초로 정량화됩니다. 이 지속 시간은 완전한 다짐을 달성하는 데 필요한 에너지를 반영하여 콘크리트의 작업성을 측정합니다. Vebe 초가 높을수록 작업성이 낮아져 콘크리트가 더 단단해지고 다지기 어렵습니다. Vebe 초가 낮을수록 작업성이 높아지고 콘크리트가 더 유동적이고 취급 및 다지기 쉽습니다.

Vebe 테스트

Vebe 테스트는 콘크리트에서 작업성을 확인하기 위해 수행되며, 가급적이면 건조 혼합물에 적합합니다.
테스트 장치는 원통형 챔버 측정 장치로 구성됩니다 ...

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fresh Concrete

굳지 않은 콘크리트

KEY TERMS AND CONCEPTS

핵심 용어 및 개념

Vebe Test

concrete workability with the vebe test

The Vebe test measures the workability of concrete, especially for dry mixes. Workability means how easy concrete is to handle and compact. The test uses a cylindrical chamber, a standard slump cone, and a transparent disc-shaped rider mounted on a vibrating table.

The cylindrical chamber measures nine and a half inches in diameter and eight inches in height. Concrete is placed into the slump cone in layers and compacted in the standard way. After the cone is removed, the concrete stays in the cylinder as a truncated cone.

A 6-pound transparent rider is then placed on top of the concrete cone. The vibrating table is turned on at 50 Hertz, which creates vertical movement and helps compact the concrete. The test is complete when the rider is fully hidden by the concrete, showing that no visible voids remain on the surface.

Workability is reported in Vebe seconds. This is the time it takes for the concrete to change from the slump cone shape to a fully compacted cylindrical shape under vibration. Higher Vebe seconds mean lower workability, so the concrete is stiffer and harder to compact. Lower Vebe seconds mean higher workability, so the concrete is more fluid and easier to handle and compact.

Concrete Workability with the Vebe Test

workability of concrete

Concrete Flow and Compaction Factors

Concrete workability is the ease with which fresh concrete can be mixed, placed, compacted, and finished. It is an important property during construction because it affects how well the material moves into position and how easily it can be shaped. Workability depends on the internal friction within the mix and the resistance it meets from molds and reinforcements. When the ingredients resist one another, concrete moves less easily. The same is true when it has to pass around barriers in the...

factors affecting workability

Concrete Workability and Mix Design Factors

Concrete workability depends on mix design factors that change how easily the material can be mixed, handled, and finished. The mix needs enough flow so it can move and be placed without losing quality. Water is a key part of this because it acts as a lubricant between the ingredients. The amount of water needed can change with the aggregates, or the solid particles in the mix. Finer particles and angular, rough-textured aggregates need more water than smooth, rounded ones because they have...

segregation in fresh concrete

How Concrete Mixes Separate During Placement

Fresh concrete can separate during placement, which changes how the mix is spread and can weaken the finished structure. This separation is called segregation. It happens when the parts of the mix no longer stay evenly blended. Segregation often occurs when concrete moves too much inside a form. It can also happen when the mix is dropped from a great height or pushed through narrow paths with sharp turns. In these cases, the heavier coarse aggregate settles at the bottom, while lighter...

bleeding in fresh concrete

Bleeding Water and Laitance in Fresh Concrete

Bleeding in fresh concrete happens when water from the mix rises to the surface after placement. The solid parts of the mix do not hold all the water as they settle, so separation occurs and water collects on top. Engineers can measure the severity of bleeding by checking total settlement or by noting how much the concrete height drops per unit height. Bleeding can create weak spots inside the concrete. Rising water may get trapped under large aggregate particles or reinforcement bars, which...

slump test

Concrete Workability Check with Slump

The slump test checks the workability of fresh concrete. Workability means how easy the mix is to place and handle. The test uses a 12-inch-high truncated cone mold that narrows from eight inches at the base to four inches at the top. Before testing, the mold is fixed to a flat base and dampened. Concrete is added in three layers. Each layer is compacted 25 times with a steel tamping rod that is five-eighths of an inch in diameter and has a rounded end. This helps spread the concrete evenly...

compacting factor test

Concrete Workability by Compacting Factor

The compacting factor test measures the workability of concrete. Workability describes how easily concrete can move and fill a mold or form during construction. This test is especially suitable for concrete mixes with aggregates up to one and a half inches in size. The setup uses specialized equipment with two truncated cone-shaped hoppers and a cylinder. All of the inside surfaces are polished to reduce friction. Concrete is first placed into the upper hopper without any compaction. Then the...

vebe test

The Vebe test measures the workability of concrete, especially for dry mixes. Workability means how easy concrete is to handle and compact. The test uses a cylindrical chamber, a standard slump cone, and a transparent disc-shaped rider mounted on a vibrating table. The cylindrical chamber measures nine and a half inches in diameter and eight inches in height. Concrete is placed into the slump cone in layers and compacted in the standard way. After the cone is removed, the concrete stays in the...

flow table test

Concrete Spread Measured by Flow Table

The flow table test measures how far fresh concrete spreads, which helps assess workability. Workability means how easily concrete can flow and settle under its own weight. The method is useful for highly flowable concrete mixes. The test uses a flow table made from a wooden board with a steel plate on top. Together, the parts weigh 35 pounds. The board is hinged to a base and measures 27.6 inches on each side. A truncated cone mold is also used. It is 8 inches high, with an 8-inch base...

key terms and concepts

Learn how the Vebe test measures concrete workability for dry mixes using vibration, a slump cone, and Vebe seconds to show compaction time.

Concrete Workability with the Vebe Test | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

civil engineering

Concrete Workability with the Vebe Test

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