Name: concrete spread measured by flow table
Uploaded: 2024-11-07T14:48:28.000Z
Duration: 1 min 12 s
Channel: JoVE

콘크리트의 작업성을 찾고 유동성이 높은 콘크리트를 평가하는 데 사용되는 흐름표 테스트는 총 중량이 35파운드인 강판을 얹은 나무 보드로 구성된 장치를 포함합니다.
힌지는 보드를 베이스에 연결하며 보드의 각 면은 27.6인치입니다.
상부 보드는 1.6인치 높이까지 들어 올릴 수 있도록 설계되었으며 테이블에는 콘크리트를 배치해야 하는 위치를 안내하는 특정 표시가 있습니다.
높이 8인치, 밑면 지름이 8인치, 상단 지름이 5인치인 잘린 원뿔은 콘크리트로 채워져 있습니다. 부드럽게 압축되고 과도한 콘크리트가 제거되며 30초 후에 원뿔 곰팡이가 조심스럽게 제거됩니다.
테이블이 15번 흔들리고 각 충격이 4초 간격으로 주어질 때마다 콘크리트가 퍼집니다.
흔들린 후 측정된 테이블의 두 가장자리에 평행한 퍼짐 정도의 평균은 콘크리트의 작업성을 나타내며, 특정 값은 중간 또는 높은 작업성에 해당합니다.

흐름표 테스트

유동표 시험은 콘크리트의 작업성을 평가하는 데 사용되는 확립된 방법으로, 특히 유동성이 높은 콘크리트 혼합물을 평가하는 데 유용합니다. 이 시험은 강철판으로 덮인 나무판으로 구성된 장치를 사용하는데, 총 무게는 약 15.87kg입니다. 이 판은 힌지를 통해 받침대에 연결되며 각 변의 길이는 70.10cm입니다.


 콘크리트는 높이 20.32cm, 밑변 지름 20.32cm, 윗변 지름 12.70cm인 절두 원뿔 몰드에 놓입니다. 콘크리트를 부드럽게 압축하고, 초과분을 치우고, 몰드를 30초 후에 제거합니다.


 시험 절차에는 상부 보드를 4.06cm 높이까지 들어 올려 4초 간격으로 테이블을 15번 흔드는 것이 포함됩니다. 이 동작으로 인해 콘크리트가 초기 원뿔 모양에서 퍼집니다. 흔든 후 콘크리트 퍼짐 범위를 테이블의 두 가장자리와 평행하게 측정합니다. 평균 퍼짐을 계산하여 콘크리트의 작업성을 평가합니다. 퍼짐의 특정 값은 콘크리트의 작업성을 중간 또는 높음으로 분류하는 데 사용됩니다. 이 시험은 콘크리트가 자체 중량으로 흐르고 침하하는 능력에 대한 중요한 데이터를 제공하며, 높은 유동성과 균일한 분포가 필요한 다양한 건설 응용 분야에 대한 적합성을 반영합니다.

콘크리트의 작업성을 찾고 유동성이 높은 콘크리트를 평가하는 데 사용되는 흐름 테이블 테스트는 나무 판자로 구성된 장치를 포함합니다.

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fresh Concrete

굳지 않은 콘크리트

KEY TERMS AND CONCEPTS

핵심 용어 및 개념

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 diameter and a 5-inch top diameter.

The concrete is placed in the mold and gently compacted. Then the excess is cleared away. After 30 seconds, the mold is removed. The table is jolted 15 times at 4-second intervals by lifting the upper board to a height of 1.6 inches. This motion makes the concrete spread out from its cone shape.

After jolting, the spread is measured parallel to the two edges of the table. The average spread is then calculated. This value is used to judge the concrete's workability. The results can place the mix in medium or high workability categories. The test gives useful data for construction applications that need high fluidity and even distribution.

Concrete Spread Measured by Flow Table

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

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...

flow table test

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

Measure concrete workability with the flow table test. Learn the mold size, jolting steps, and how spread is used to classify flowable mixes.

Concrete Spread Measured by Flow Table | 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 Spread Measured by Flow Table

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