Roller compaction and wheel tracking apparatus

Standard : EN 12697-33, EN 12697-22

The special feature of the machine is the integration of two distinct functions in a single system; the first allows the compaction of slabs of bituminous mixtures to a controlled density, the second is for performing the wheel tracking test.

A “kneading” system is used for compaction and consists in positioning between the roller and bituminous mixture a series of sliding metal plates that are free to move vertically, guided by the internal mould surfaces. 

The wheel tracking test apparatus is the “small-size” type prescribed in the Standard.

The integration of the two functions is made possible by the particular machine design (patented); the cylindrical roller is replaced with two coaxial disks rolling along lateral projections of the sliding plates. 

On removing the plates, the disks are lowered over the two other edges of the mould, so contact between the bituminous mixture surface and the wheel of the wheel-tracking apparatus is made.

As for the mechanics, the machine is composed by a horizontal axis driven by a brushless motor coupled with a ball-screw assembly and by a vertical axis driven by a Bellofram cylinder controlled by a pneumatic servo-valve.

There are three sensors installed in the machine: an incremental encoder for the horizontal axis position, a magnetostrictive sensor for the vertical axis position, and a load cell for force.

Each of these sensors can be used as reference by the closedloop, computer controlled system with feedback; the user interface is a touch screen.

The test area is enclosed within a ventilated climatic chamber with automatic thermo-regulation up to 60°C.

ROLLER COMPACTOR

In order to obtain slabs of the desired density and size, an initial levelling cycle may be actuated that is intended for evenly distributing the mix in the mould.

The compacting phase may be programmed with constant or increasing load, i.e. with increasing deformation. It is possible to set a defined slab thickness or the number of cycles.

WHEEL TRACKING

The refined system of transduction, control and actuation of the roller compactor remains active during wheel tracking test in order to compensate, insomuch as it is possible, the inertial effects of load mass due to irregularities in rut depth. 

Both the procedures prescribed by Standards may be performed.

USER INTERFACE

Users are required to input basic parameters and procedures; test execution, measurements, data processing and test report compilation are completely automatic.

Power supply: 380 V, 50 Hz, 16 A, three phase + N + E, 6000 W

Air supply: 10 bar pressure; dry, non-lubricated air (compressor and accessories are not supplied)

Dimensions: 1850* x 800 x 1990 (h) mm

Weight: 800 kg