In all areas, each specific tool will be designed and manufactured to meet a specific need. The world of construction is no exception to this rule, and every tool in this field has a specific need. Concrete vibrating, however, is one of the tools made to meet technical needs during concreting. The nature of concrete is such that when emptied, due to its special paste state, it may mix with air or for any reason the air under it may be trapped.
When you cover a large surface with concrete, it is not at all strange to encounter air bubbles trapped on the concrete surface. Of course, air bubbles are not only formed on the surface, but can sometimes be seen in the middle layers as well.
In the meantime, the concrete vibrates help to release these trapped air bubbles, get to the concrete surface and get out of it completely. Now the question will be raised on what basis and based on what technique does the concrete vibrate remove air bubbles from the poured concrete? But before we get into that, let's start with the question of why we should basically vibrate these bubbles out of the concrete mix. As mentioned, the purpose of using concrete vibrators is to remove bubbles from the concrete paste, but why should we remove these bubbles from the concrete?
In short, if air bubbles remain in the concrete mix, the concrete will become porous and its strength will decrease. If you are familiar enough with the knowledge of material strength, you will understand how the presence of empty pores and holes in the concrete body after drying, will cause problems with all forces and in practice your concrete will have a weak resistance. Therefore, in order to avoid the weakness of concrete forces, it is necessary to use concrete vibrators or other similar devices.
So far, you've probably figured out what the use of concrete vibration is, but now it's time to look at how concrete vibration does its job. One of the solutions and perhaps the only solution to remove air bubbles from the concrete paste is vibration.
Vibration with constant tensions in different layers of concrete will cause air to escape from it. This is exactly why this practical device is called concrete vibration. Therefore, the basis of concrete vibration work is to create vibrations with high frequency and at the same time strong vibrations in the concrete paste layers. Concrete vibrators are available in different types and brands, but they all have the same system and work the same way.
In all vibrations, concretes cause vibration, or vibration, with a single motor, usually located in the concrete vibration handle. The vibration created in the vibrator motor will be transmitted to the concrete by a hose-like piece, called a vibrator hose.
The head of the concrete vibrator hose is usually made of durable metal alloys and is placed in the concrete paste and transmits this vibration to it. Note that because the concrete is freshly poured and still wet in the correction, it is permeable and the vibrator hose head can be dipped into it.
We basically have two categories of concrete vibrators: gasoline and electric. Surface vibrators are located on top of the concrete that has been poured.
They are extraordinary when the concrete is less than 10 inches or in flat slabs. These are recommended on shallow structures or slabs and when used in combination with concrete having a low water-to-cement ratio. When you are pouring a slab or patching a surface, this is the type of vibrator that should be used.
Don't use a surface vibrator when there are large volumes of concrete or when the slab is too thick, and the lower layer of concrete will not receive adequate vibration. Rebar shaker is one good alternative to traditional vibration techniques. The technology is very similar to a regular vibrator, but in this case, the device is slipped over the top of the reinforcing bar and "shakes" or transmits the vibration into the concrete. It can be found in different diameters and can result in great savings in man hours and reduces clean-up activities.
This tool will shorten the time it takes to pouring concrete into a cell or in a very tight space. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors.
It is important that the vibrator head not be moved around laterally while consolidating in this manner.
In terms of effects on concrete due to inserting the vibrator at an angle, the effectiveness of consolidation can be compromised. Vibrator heads contain an eccentric weight that rotates at high speed and exerts vibratory action perpendicular to the axis of the head.
If the head is inclined, there is a risk that the radius of action of the vibrator will not consolidate some portions of the concrete. Thank you for the comment Mark. For an accurate response to your question, I recommend you contact the Masonry Institute of America as they have more knowledge on this subject.
Since lime pointing is not common in precast concrete production, it is not a familiar practice with our technical service engineers. Its about square feet around this boxed wall. Thinking of running 2 vibrators at once it hopes to keep up with the hose while getting maximum vibration. Any suggestions on how high I should pour my lifts….
John, do you own or are you renting your vibrators? Do you have door bucks, window bucks or other block outs,conduit etc. Obviously you will have a double curtain of re-bar in this shear wall so you will want to run a trim hose so you can insert it down into your wall so you are not dropping your mud the full 17 ft. That much force can cause pillowing and blowouts on your forms and rock pockets through separation of the aggregate.
I would not pour higher than 4 ft per lift unless you have block outs ie. You will need to seal the bottoms on the first lift. Run as high of a slump as allowed to insure there are no voids. Good luck. Are these walls exposed? If so run you vibrator down the side of your forms that are not exposed. The vibrator head pulls the air to its self and away from the exposed surface.
There are vibrators with 50Hz, Hz and then there are some vibrators on the market with adjustable frequency from Hz. Thank you for the comment Janis. I forward your question to our Technical Services engineers. The following response is from Claude Goguen, P. Vibrators used to consolidate concrete are characterized by two factors: amplitude and frequency. The frequency is the number of vibration cycles per minute and is often presented as revolutions or vibrations per minute rpm or vpm or in hertz Hz.
Generally, as the diameter of the vibrator head increases, the frequency decreases and the amplitude increases. If you have a thinner concrete member, generally you would use a higher frequency and a lower amplitude as opposed to larger pieces, which will require less frequency and more amplitude. Using improper frequency in consolidating concrete can result in durability and finish issues.
Using too high a frequency can end up losing entrained air, which can impact durability. Also, using a high frequency can result in higher cement paste and water concentrations at the surface, which can result in drying shrinkage and crazing.
If frequency is too low, the entrapped air can remain, which can affect the durability and finish quality of the structure. This is the frequency while the vibrator is immersed in concrete. Further guidance can be obtained by contacting internal vibrator suppliers directly. Please can you give me any advice? Thank you for your comment John. The following response is from Eric Carleton, P. From your description, it would appear your trial concrete mix is very stiff. Consequently, consideration might be given to utilize a water reducer admixture or if the mix design permits added water to provide fresh concrete properties slump which would permit this internal method of consolidation.
Certainly you will need to increase the slump for workability to finish the floor slab. If your mix does require a stiff mix for quick form removal i. In these cases, vibrators are connected to the formwork framing, or the entire form is rigidly attached to a vibrating table that applies appropriate energy to the concrete.
Increasingly stiff mixes as described are being used in flatwork and mass concrete pours, but the consolidation is done by large vibrating rollers more commonly associated with asphalt paving processes.
This consolidation process may not meet the interior floor tolerances required. Dear sir, Can we used viberotar in Roof slab? Thank you for your comment Najib. If you can share a bit more about the specific problem you are having using a vibrator, I can pass that along to our Technical Services engineers for a response. We pour a bag at a time and try to get the mix down around the rebar and then ultimately we burn the finish. Thanks, Don. Thank you for the comment Don. I forward this to our Technical Services engineers.
The following response is from Evan Gurley. If you are using conventional slump concrete , you may want to use internal or external vibrators to consolidate the mix and to work it around reinforcing steel and any inserts or blockouts.
Vibration or consolidation is an important component to address and is the most widely used method for consolidating concrete. When concrete is vibrated, internal friction between the aggregate particles is temporarily disrupted allowing the concrete to behave like a liquid. It settles in the form under the action of gravity and large entrapped air voids rise more easily to the surface.
Internal friction is re-established in the mixture as soon as vibration stops. Stinger vibrators are commonly used to vibrate concrete.
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