What is concrete vibrator and why is it so important to vibrate concrete after placing?
- Thread starter Quest Bot
- Start date
The vibrator is a mechanical device to consolidate or compact the concrete. A vibrator consolidates concrete in a two-part process. The first waves liquify the concrete so it flows better and the continuing waves knock out air bubbles
Right after it’s placed, concrete contains as much as 20% entrapped air, The amount varies with mix type and slump, form size and shape, the amount of reinforcing steel, and the concrete placement method.
At constant water-cement ratio, each percent of air decreases compressive strength by about 3% to 5%.
Consolidating the concrete, usually by vibration, increases concrete strength by driving out entrapped air. It also improves bond strength and decreases concrete permeability.
The problems associated with under vibration include:
- Honeycombing
- Excessive entrapped air
- cold joints
- subsidence cracking
- segregation
- form deflection
- form damage or failure
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