Technical Knowledge
How to avoid over-vibration with laser leveling on fiber concrete?

Fiber-reinforced concrete (FRC) is notoriously fickle. If you over-vibrate, the fibers-whether steel or synthetic-tend to sink or "nest," leaving you with a non-homogeneous slab and a "hairy" surface that is a nightmare to finish.
With a laser leveling, the goal is to keep the fibers suspended in the paste while achieving your ±3mm tolerance. Here is how to dial in your machine:
1. Match Vibrator Frequency to Slump
Over-vibration usually happens when the centrifugal force is too high for the concrete's consistency.
The Rule of Thumb: For high-fiber mixes, you generally want high frequency but low amplitude.
Adjustment: Most laser leveling (like Vanse) allow you to adjust the hydraulic flow to the vibrator motor. If you see "fat" (excessive cream/paste) rising more than 2mm–3mm above the fibers, slow the vibrator RPM down immediately.
2. Monitor leveling Head Speed (The "Advance" Rate)
If the machine moves too slowly while the vibrator is screaming, you are effectively "drilling" the fibers down into the subgrade.
The Sweet Spot: Maintain a consistent forward (or pulling) speed. If you have to stop the machine for any reason, shut off the vibrator immediately. Leaving a vibrating leveling head stationary for even 5 seconds will create a permanent "soft spot" or depression in a fiber floor.
3. Check the "Vibrator Drop" Height
The vibrator should not be buried in the concrete.
Positioning: The vibrator plate should just "kiss" the surface of the concrete as the auger levels it.
The Sink Effect: If the vibrator is set too low, it pushes the larger aggregate and fibers down, leaving only weak laitance on top. This leads to surface scaling later in the floor's life.
4. Manage the "Fiber Ball" Risk
Fibers can sometimes clump (balling) before they even hit the leveling.
Auger Interaction: Ensure your auger is set to the correct height (3mm to 5mm above finished grade). The auger’s job is to "cut" the excess; if it’s too low, it will snag fibers and drag them, creating tears in the surface.
Avoid "Double-leveling": With fiber, try to get it right in one pass. Re-vibrating the same area almost guarantees the fibers will settle too deep.
5. Use a "Cloud" or Offset Receiver Setting
Because fibers can make the mix "stiffer," the leveling head might "ride up" on the material.
The Fix: Don't increase vibration to force it down. Instead, adjust your Laser Offset. If the machine is riding high, lower the laser receivers by 1MM or 2MM to compensate for the material's resistance without over-working the paste.
Summary Checklist for Fiber Concrete
| Variable | Adjustment for Fiber | Goal |
| Vibrator RPM | Reduce by 15-20% | Prevent fiber sinking |
| Travel Speed | Faster / Consistent | Prevent "hot spots" |
| Auger Height | Slightly Higher | Avoid snagging/tearing |
| Slump | Maintain 100mm – 125mm | Ensure flow without segregation |
Pro Tip: Have a "muck man" with a come-along tool standing by to watch the auger. If he sees a "beard" of fibers building up on the plow, you need to stop and clean the head, or it will ruin your FF numbers.
Would you like a guide on how to properly "dry-shake" hardener over a fiber-reinforced floor without creating delamination? Contact us NOW
Note: The parameters provided in this document are for reference only and are not mandatory. Due to differences in technical characteristics between different brands and models of laser levelers, please consult the manufacturer for a suitable solution before actual operation. This reference document assumes no responsibility for any issues arising from failure to follow the manufacturer's instructions.
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About the Author: Shandong Vanse Machinery Technology Co., Ltd.
Shandong Vanse Machinery Technology Co., Ltd. is a high-tech manufacturer specializing in concrete construction machinery, including laser screeds and related equipment. The company integrates R&D, production, and global sales, with products exported to over 60 countries and widely used in infrastructure projects worldwide.
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