Name: concrete compaction with vibrators
Uploaded: 2024-11-07T14:48:35.000Z
Duration: 1 min 19 s
Channel: JoVE

Mechanical vibrators are used to compact freshly placed concrete in forms and around the reinforcement to expel the entrapped air and form a dense concrete mass.
Commonly, an internal vibrator, such as a poker vibrator, is plunged swiftly through the entire thickness of the freshly placed concrete and partially into the underlying layer of concrete existing in a plastic state.&#160;
Vibrations are provided every 2 to 3 feet along the concrete surface for durations spanning 5 seconds to 2 minutes, depending on the concrete&#39;s consistency.
The poker is gradually pulled to ensure that the space it had occupied in the concrete seals naturally.&#160;
Unlike internal vibrators that work directly on the concrete, external vibrators are firmly attached to the formwork via an elastic support, allowing simultaneous vibration of both the form and concrete.
It is used for precast or thin in situ sections and may require positional adjustments during concrete pouring.
Alternatively, a vibrating table can be used to provide uniform vibrations to precast concrete units by clamping the formwork to the vibrator.&#160;

vibrating concrete

Mechanical vibrators are instrumental in compacting newly poured concrete within formwork and around reinforcements. This process is essential to eliminate trapped air pockets and establish a dense concrete mass. One widely used method is vibrating by internal vibrators, often referred to as a poker vibrator or immersion vibrator. It is rapidly inserted through the full depth of the freshly laid concrete and slightly extends into the layer below it (which remains in a plastic state). Consistent vibrations are applied across the concrete surface at intervals of every 2 to 3 feet for a period of 5 seconds to 2 minutes, depending on the consistency of the concrete mix. As the vibrator is slowly withdrawn, the hole left behind is naturally sealed, preventing the formation of voids.
Another method employs external vibrators that are attached to the formwork to vibrate the formwork and the concrete simultaneously. This is used for precast elements or thinner sections of concrete. In contrast to internal vibrators that directly vibrate the concrete, external vibrators do additional work by vibrating the formworks, making them less efficient than the internal vibrators. Occasionally, external vibrators have to be shifted from place to place depending on the placement of the concrete. For precast concrete units, a vibrating table is used, wherein the formwork is fixed directly onto the platform to achieve a uniform vibration throughout the unit.

Vibrating Concrete

Mechanical vibrators are used to compact freshly placed concrete in forms and around the reinforcement to expel the entrapped air and form a dense ...

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JoVE Core

Civil Engineering

Unit 1

Mixing, Placing and Curing Concrete 

KEY TERMS AND CONCEPTS

concrete compaction with vibrators

Concrete compaction with vibrators helps newly poured concrete settle inside formwork and around reinforcement bars. The goal is to remove trapped air pockets and create a dense concrete mass. Mechanical vibration is a key part of that process.

One common method uses an internal vibrator, also called a poker vibrator or immersion vibrator. It is quickly inserted through the full depth of the fresh concrete and slightly into the layer below, which is still in a plastic state. The vibrator is applied across the surface at intervals of about 2 to 3 feet for 5 seconds to 2 minutes, depending on how stiff or fluid the mix is. As the tool is slowly pulled out, the hole closes on its own and helps prevent voids.

External vibrators are another option. These are attached to the formwork so the form and the concrete vibrate together. They are often used for precast elements or thinner concrete sections. Because they also vibrate the formwork, they do extra work and are less efficient than internal vibrators. In some cases, they must be moved from place to place as the concrete is placed.

For precast concrete units, a vibrating table can be used. In this setup, the formwork is fixed directly to the platform. The table provides a uniform vibration throughout the unit and helps compact the concrete evenly.

Concrete Compaction with Vibrators

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Concrete compaction with vibrators helps newly poured concrete settle inside formwork and around reinforcement bars. The goal is to remove trapped air pockets and create a dense concrete mass. Mechanical vibration is a key part of that process. One common method uses an internal vibrator, also called a poker vibrator or immersion vibrator. It is quickly inserted through the full depth of the fresh concrete and slightly into the layer below, which is still in a plastic state. The vibrator is...

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key terms and concepts

Learn how internal vibrators, external vibrators, and vibrating tables compact fresh concrete, remove air pockets, and improve density in formwork.

Concrete Compaction with Vibrators | 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 Compaction with Vibrators

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