- The first step to a more effective roller -

Benefits for the roller manufacturer

CMV = established value for bearing capacity for 25 years

Over 4000 units installed worldwide

Lowest price - adapted for factory installation

Small size - can be integrated in the instrument panel

No training is necessary

Custom design possible

System principle
The Compactometer™ is based on the principle that the more compact the soil, the more rebound it gives on impact.

A sensor mounted on the drum bearing continuously measures impact forces that arise when the vibrating drum works on the surface. Signals from the sensor change in character as the ground becomes harder and more stable during compaction.

These signals are converted into values that indicate a relative measure of the bearing capacity of the ground. Sometimes this value needs to be calibrated into a specified density (degree of compaction).

The bearing capacity expressed as a "modulus of elasticity" is a measure of the ability to carry a load. One might say that bearing capacity is a better measure of the strength in soil construction than the density.

Typical CMV-values

The Compactometer™ normally gives the following Compaction Meter Values (CMV) for the different typical soils in a compacted state.

Rock fill 60 - 100
Gravel 30 - 80
Sand 20 - 50
Clay and Silt 5 - 30

Clays and silts are sensitive to water content variations and the bearing capacity can be very low when the water content is higher than the optimum water content. This will of course also be reflected in the observed CMV.

Vibration frequency and vibration amplitude, rolling speed and rolling direction will influence CMV to a certain extent and should therefore be kept constant.


 The Compactometer™ ALFA-030

How does the Compactometer™ function?

An acceleration sensor (1) continuously measures the vertical vibration of the drum. The sensor converts the vibrations into electrical signals that are transmitted to the processor (2).

The processor analyses the sensor signals, and calculates the Compaction-Meter-Value, CMV, the frequency and the Resonance-Meter-Value, RMV. These values are then shown on the respective dials, (3), (4) and (5).

The CMV increases with the stiffness of the compacted layer and reflects the bearing capacity of the surface including underlying layers. The more the soil material is compacted, the higher the CMV.

For a given soil layer and roller, there is a maximum compaction and when this is reached, CMV ceases to increase. Thus, the roller operator knows then, that further passes would not increase the degree of compaction.

The system includes:

- CMV, Compaction Meter Value
- RMV, Resonance Meter Value  (double jumps)
- Frequency, Hz
Digital Processor(180 x 105 x 36 mm)
A-sensor + Cable (64 x 58 x 34 mm)
I-sensor + Cable

Power connection cable

CDS™System connection cable


Benefits for the end user
Time and money savings - (Contractor)   Quality assurance - (Investor)
Reduce the number of roller passes by preventing over-rolling!   Attain a uniform compaction!
Instant self-control!    
Make the selection of representative points for spot tests possible, which reduces the number of tests!   Improve compaction by preventing reloosening and overcompaction!
Increase the roller's lifetime by early warning of double jumps!   Increased competence will increase the motivation!