Name: concrete workability check with slump
Uploaded: 2024-11-07T14:48:28.000Z
Duration: 1 min 20 s
Channel: JoVE

슬럼프 테스트는 콘크리트 작업성을 측정하고 12인치 높이의 잘린 원뿔 주형을 사용하여 바닥에서 8인치에서 상단에서 4인치로 좁혀지고 콘크리트를 채우기 전에 평평한 바닥에 단단히 부착됩니다.
콘크리트는 3 개의 층으로 댐핑 된 주형에 추가되며, 각 층은 직경이 5/8 인치이고 끝이 둥근 강철 탬핑 로드를 사용하여 25 번 압축됩니다. 마지막으로 상단 표면이 벗겨집니다.
채우기 후 원뿔이 부드럽게 들어 올려지고 콘크리트가 주저앉습니다. 슬럼프(slump)라고 하는 높이의 감소는 가장 가까운 1/4인치까지 측정됩니다.
균일한 슬럼프는 진정한 슬럼프라고 하며, 콘크리트가 금형 아래로 미끄러져 내려가는 것은 전단 슬럼프를 나타내며 재테스트가 필요합니다. 지속적인 전단 슬럼프는 혼합물이 응집력이 부족하다는 것을 시사합니다.
때때로, 콘크리트는 린(Lean) 혼합물에 대해 붕괴될 수 있으며, 이는 린(Lean) 혼합물에 대한 슬럼프 테스트의 신뢰성이 없음을 강조합니다.
너무 높거나 너무 낮은 슬럼프는 즉각적인 경고 역할을 하여 벌크 콘크리트의 혼합물과 관련된 문제를 수정하도록 촉구합니다. 다양한 작업 능력에 대한 권장 슬럼프 값이 미리 결정됩니다.

슬럼프 테스트

슬럼프 시험은 콘크리트의 작업성을 측정하는 데 널리 사용되는 방법입니다. 바닥에서 20.32cm에서 꼭대기에서 10.16cm로 가늘어지는 30.48cm 높이의 절두 원뿔 몰드를 사용합니다. 시험 전에 몰드를 평평한 바닥에 단단히 부착하고 적십니다.


 콘크리트를 3개 층으로 틀에 부어 시험을 실시합니다. 각 층은 직경이 1.58cm이고 끝이 둥근 강철 탬핑 막대로 25번 압축하여 균일한 분포를 보장하고 공기 주머니를 제거합니다. 압축 후 콘크리트의 상단 표면을 평평하게 합니다.


 몰드가 채워지면 부드럽게 위로 들어올려 콘크리트가 중력으로 인해 아래로 처지게 합니다. 그런 다음 슬럼프라고 하는 콘크리트 높이의 감소를 가장 가까운 0.63cm까지 측정합니다. 콘크리트가 원뿔 모양을 유지하는 적절한 슬럼프는 진정한 슬럼프입니다. 콘크리트가 붕괴되거나 퍼져서 전단 슬럼프를 나타내는 경우, 혼합물에 응집력이 부족하고 구조적 적용에 문제가 될 수 있음을 시사하므로 테스트를 반복해야 할 수 있습니다.


 지나치게 높거나 낮은 슬럼프 값은 콘크리트 혼합물에 잠재적인 문제가 있음을 나타내는 지표로, 조정이 필요합니다. 슬럼프 테스트는 대량 콘크리트 작업에서 즉각적인 수정 필요성을 파악하는 데 특히 효과적이지만, 콘크리트가 붕괴되는 경향이 있는 린 혼합물의 경우 신뢰성이 떨어질 수 있습니다. 권장 슬럼프 값은 다양한 유형의 작업성에 대한 특정 요구 사항에 따라 미리 결정됩니다.

슬럼프 테스트는 콘크리트 작업성을 측정하고 12인치 높이의 잘린 원뿔 주형을 사용하여 바닥에서 8인치에서 4인치로 좁혀집니다.

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fresh Concrete

굳지 않은 콘크리트

KEY TERMS AND CONCEPTS

핵심 용어 및 개념

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 and remove air pockets. The top surface is then leveled off.

After the mold is full, it is lifted straight up. The concrete drops under gravity, and the drop in height is called the slump. The slump is measured to the nearest quarter inch. If the concrete keeps its cone shape, it is called a true slump.

If the concrete collapses or spreads out, it is a shear slump. That result can mean the mix lacks cohesion and may not work well for structural use. Very high or very low slump values also point to problems in the mix and may require adjustment. The slump test is especially useful for finding quick fixes in bulk concreting work, but it may be less reliable for lean mixes that tend to collapse. Recommended slump values are set ahead of time for the workability needed in each type of job.

Concrete Workability Check with Slump

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

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

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 slump test measures concrete workability using a cone mold, layered filling, tamping, and slump measurement for fresh concrete.

Concrete Workability Check with Slump | 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 Check with Slump

Description

Transcript