When it comes to concrete work, whether it is the concrete floors or the parking, concrete vibrators are one of the common tools needed to get the best results. They are used for compaction of concrete. Concrete vibrators remove air bubbles and air pockets from freshly poured concrete by giving it a vigorous shake, thus making a strong concrete. They are available in a variety of shapes and sizes. This article provides brief details on different types of concrete vibrators.
Different Types of Concrete Vibrators
Let’s learn about different types of vibrators in detail:
01. Internal Vibrators for Concrete
Internal vibrators are popular as needle, poker, or immersion vibrators. Essentially, they are made up of a power source and a long flexible tube with a vibrating head at the end. The power source might be either an internal combustion engine, which runs on gasoline or diesel, or an electric motor driven by electricity. Within the vibrating head is located an eccentric weight that is rotated by a flexible shaft that is housed inside the long tube. As per author of Concrete Technology by MS Shetty, the vibrator has a frequency of around 12,000 cycles of vibration per minute. The vibrating head is put into the concrete. Maximum output is achieved when the vibrating head is advanced into contact with the concrete. The cost of a needle vibrator depends on several factors, including the manufacturer and the quality of the device being purchased.
02. External or Shutter Vibrators for Concrete
External vibrators are popular as formwork or shutter vibrators. These vibrators are used for concreting columns, walls, or precast concrete. The use of a formwork vibrator produces a good finish to the concrete surface. External vibrator consumes more power as the vibration is given to the concrete indirectly through the formwork. These vibrators have low efficiency compared to internal vibrators. The principle of an external vibrator is the same as that of an internal one, but the frequency is usually between 3,000 and 6,000 vibrations per minute (vpm) although some vibrators reach 9,000 vpm. They are used in places where an internal vibrator would be impractical, such as narrow or crowded spaces, arches, tunnel linings, etc.
03. Surface Concrete Vibrators
Surface vibrators are popularly known as screed board vibrators. They are directly placed on the concrete mass. During the screeding process, they vibrate the concrete from the surface. They are considered effective for a depth of about 20cm. In modern construction practices like vacuum dewatering or slip-form paving techniques, screed board vibrators are commonly used.
04. Table Concrete Vibrators
The table vibrator is made of a rigid steel platform that is mounted on a flexible spring. It has extremely low energy consumption and high operational efficiency. They are commonly used for vibrating concrete cubes. The concrete is put into moulds that are set up on the platforms and clamped to the vibrating table so that the mould and the concrete vibrate together. Vibrating tables are used to compact hard and stiff mixtures that are used to make precast structural components in factories and lab specimens. As per the author Neville, “The range of frequency achieved lies between 1,500 and 7,000 vibrations per minute (vpm).”
Concrete Vibrating Tips
- Avoid over vibrating the concrete, as this can cause the mixture to disintegrate. Additionally, avoid under-vibrating the concrete because air may still be trapped in the lower cement layers, which results in a weak concrete structure that breaks quickly with little pressure.
- The most suitable technique for using an internal vibrator is to progressively remove it at a speed of about 25 mm per second. More vibration is required if bubbles still appear when the concrete vibrator is being removed.
- Avoid cold joints from forming in concrete layers as you pour a fresh layer of cement mixture. Use a vibrator to deeply penetrate the pour and mix the previously poured layer with the newly poured one.
- To ensure a uniform distribution of aggregate and concrete, vibrating should only be done vertically for optimal effectiveness. Horizontal motion increases the likelihood that the vibrator will tangle with the rebar or reinforcing steel and can cause uneven distribution.
- Depending on the structure being built or the size of the working area, use the proper kind of concrete vibrator. For smaller jobs that are easier to handle and more efficient, think about using a small, lightweight concrete vibrator.
- Consider keeping a backup concrete vibrator on hand so you can quickly switch to a different tool if the primary one experiences any issues while you’re working with it.
Conclusion
Different building and structural applications require different sizes and types of concrete vibrators. Because concrete is made up of particles of variable sizes, vibrators with adjustable vibration speeds are necessary for optimal compaction. You can start narrowing down your options for the perfect concrete vibrator by reading the brief descriptions we’ve provided here. If you select the best vibrator for the job, you will have a much easier time to finish the task.
If you are interested in more such blog, don’t forget to read following article too:
Commonly used Heavy Construction Equipment
Image Courtesy : Image 2, Image 3, Image 4, Image 5
Author Bio
Fathima Israr Khan- I’m Fathima Israr Khan, an MTech second-year student in Geotechnical Engineering at NIT Silchar.
