The process of mixing concrete adds a considerable amount of air. In fact, trapped air can account for up to 20% of the volume of wet concrete. Because concrete does not flow as a continuous solution further air becomes trapped as the concrete is poured into the form.
Why Does The Amount Of Air In Concrete Matter?
While pin head sized pockets of air can increase frost resilience, larger air pockets weaken the concrete and spoil the finish. Concrete may also fail to bond with reinforcement structures and joints, unless it is properly compacted using effective tools and the right techniques.
Vibrating wet concrete is the most effective way to remove trapped air, and specialist concrete vibrating equipment is essential for creating compact, strong and smooth results.
The benefits of industrial concrete vibrators include:
- Increased concrete density
- Increased concrete strength
- Improved bonding with reinforcement structures and construction joints
- A smooth finish
Types Of Concrete Vibrator
The type of concrete vibrator required for the job depends on the consistency of the slump mix, size of the concrete form and the depth of the concrete.
Let’s take a look at the most effective vibrators for different tasks.
- Surface vibrators - Pan or screed board vibrators are commonly used for industrial flooring, pavements and paving slab concrete compaction. This method is only suited for very shallow concrete.
- External vibrators - External vibrators transmit vibrations through the formwork at regular horizontal and vertical intervals. This method is effective for delicate work, such as archways.
- Internal vibrators – Internal vibrators, known as pokers, are immersed into wet concrete at regular intervals and slowly withdrawn. The vibrations cause the air bubbles to rise. This creates dense, smooth concrete that is perfect for foundations, beams, slabs and walls.
How To Get Smooth Concrete
The most effective vibrators for concrete compaction are high frequency internal pokers. Premium electric models can achieve a frequency of 12,000 vibrations per minute (vpm) for flawless concrete compaction. However, even with the highest quality equipment, poor technique can ruin your concrete.
Here are our top ten tips on how to use concrete vibrators for effective concrete compaction:
- Always use the correct size and length of poker head for the concrete form, slump consistency and depth.
- Immerse the head vertically for effective compaction.
- Never allow the head to come into contact with the form surface or reinforcement bars.
- Compact one course at a time, allowing the head to partially enter the previous course to ensure a solid bond.
- Immerse the head at the correct intervals along the form. This will be approximately ten times the head diameter.
- Do not over vibrate – This will cause the aggregate to settle and the water and paste to rise.
- Do not under vibrate – This leaves voids and air pockets which weaken the concrete and damage the appearance.
- Always clean your equipment before the concrete has time to harden.
- Ensure your equipment is regularly maintained to prevent breakages and costly downtime (this is something we can offer).
- Seek concrete vibrating equipment that can accommodate interchangeable poker heads. This will provide flexibility to move swiftly from one compaction job to another.
Quality & Service You Can Depend On
At Key Services, we’ve been supplying concrete vibration equipment for over 40 years. Our team know everything there is to know about concrete compaction and how to keep your equipment working effectively.
We provide a full maintenance and repair service and only supply products we can depend on for quality, reliability and high stock availability.
Get Your FREE Guide Today
For advice and tips on selecting the right concrete vibrator, download The Buyers Guide To Vibrating Pokers. It’s completely FREE! Click here to claim your copy today.
Should you have any questions, call on 02476 559 770. We’re always happy to help.