Rhéomètre pour béton bitumineux modèle DSR II de Bohlin

Developed in close cooperation with SHRP researchers, the Bohlin DSR set new standards in asphalt testing technology offering precise and accurate unattended operation. Indeed, the SuperPave test test protocols for binders were developed using Bohlin instrumentation and the DSR has become the most commonly used rheometer at both State and Federal DOTs.
Building on the technology and success of the original DSR, the Bohlin DSRII offers testing labs even greater ease of use as well as constituting a flexible and fully upgradable work-station.
Of course, the DSRll can be used for all asphalt testing requirements including the AASHTO methods TP5, PP6, MP1 and ASTM. It also meets or exceeds SHRP requirement B-003.

For QC testing, sample throughput is of paramount importance. Therefore, every feature of the DSRII design has been implemented with the goal of minimising the time required to make each measurement.
This includes loading the sample through to reaching thermal equilibrium, collecting the data and finally cleaning the unit. For example, the DSRII has been designed with measuring systems and gap setting to eliminate much of the operator time required when using conventional or modified general purpose rheometer units.
Additionally, Bohlin’s temperature control system offers rapid thermal equilibrium as well as extremely stable control.

Bituminous materials are extremely temperature sensitive with large variations in their material properties over a fraction of a degree centigrade. Even small temperature gradients in the sample and errors between the sensor temperature and the mean sample temperature can render rheological data unreliable.
To overcome this problem, the Bohlin DSRlI incorporates a clean, easy to use system which completely immerses the sample in a temperature controlled fluid (patent pending).
For testing bituminous materials, the Bohlin design out-performs all other types of temperature control including gas ovens and heated lower plates. This is because the relatively high thermal conductivity of the fluid, which is in direct contact with the sample, allows for a much better heat transfer into the test specimen (up to 25 times faster). Temperature gradients within the sample are completely eliminated and the temperature of the sample is maintained to within 0.1 °C of setpoint. Thermal equilibrium is near instantaneous due to the intimate contact of the sample and the circulating fluid.

The DSRII gap can easily be changed to any desired value. For simplicity, both of the specification testing positions are clearly marked and can be easily selected.
With most rheometer systems, the gap must be constantly reset during a day’s testing and must be readjusted every time the temperature or the measuring systems are changed. The Bohlin DSRII addresses both of these issues eliminating continual resetting of the gap to help optimise sample throughput and eliminate operator error.
The DSRII measuring systems are designed to be easily interchangeable. The unique coupling arrangement of the lower system to uick fit upper systems ensure that the gap need not be reset whenever the upper or lower plates are removed or replaced. If necessary, samples can be loaded remotely onto the lower plate for convenience.
Changes in temperature may affect the gap zero point due to thermal expansion of the measuring systems. To remove the need for gap adjustment, the DSRII features automatic expansion compensation (AEC) to keep the gap constant as the temperature changes.

The DSRII is offered in two forms having either a Mechanical or an Air Bearing.
Mechanical Bearing units can also be upgraded to Air Bearing units if testing requirements change.
The Mechanical Bearing system offers a cost effective solution for SuperPave testing and is especially suitable for applications where compressed air is not available. It exceeds all current SuperPave testing protocols.
The Air Bearing version requires a supply of compressed air and is warranted to withstand even the most adverse industrial laboratory environments. It is ideally suited to specification testing as well as having excellent research capabilities and longevity. The Air Bearing system used by Bohlin is impervious to dirt and other contaminants as well as being extremely strong and robust.