Together with the manufacturer of measuring devices RHEOTEST Messgeräte Medingen GmbH a rheometer for building materials has been developed after a draft by the research laboratory R. VOGEL - FORSCHUNG.

The special merit of this device is its universal applicability in the determination of material properties. The materials investigated range from fluids to solids.

It is well suited for both rotation tests and creep tests. The measuring drive enables investigations to be made that are focussed on shear strain and shear velocity.

The field of application of the rheometer is not limited to building material laboratories and material testing institutes, it is also part of the equipment of research, development and teaching institutions as well as of plants of the basic industry dealing with building materials and their components. It may be employed in routine production control, in dealing with complaints, in testing the effects of modified components and last not least in the development of new building materials.

The technical data of the system of measuring head - control unit - software by RHEOTEST which was tested in all stages of development by R. VOGEL - FORSCHUNG are as follows:

The operation of the device requires a computer with pentium processor, a MS-Windows-oriented operating system and a screen. The connection between PC and control unit will be handled via the serial port.

For the investigation of plaster mortar and structural mortar
the test arrangement of the RHEOTEST^Ò RN consists of an even plate carrying the plaster sample and the power transmitting element, the ring segment sensor. The plaster mortar must be applied to the sample carrier in such a way that the sample reflects the preceding steps of mixing, pumping and spraying. This constellation of forces leads to

• a practice-oriented variant of the sample carrier. A brick, an aerated concrete block or other building material is taken from a wall that has been sprayed with mortar. This plaster-covered body is taken to the rheometer without disturbing the mortar layer. If a sample is prepared in this way the absorbing capacity of the plaster base is also taken into account.
• an abstracted variant. Use is made of the procedure for the determination of the flow diameter acc. to DIN-EN 459 and the equipment .After the determination of the flow diameter and without disturbing the equilibrium of forces after the dynamic loading of the mortar, the mortar pad is put together with the flow table plate on the tubular support. If the absorbing capacity of the plaster base is to be taken into consideration an additional porous base is used.

Both variants of sample preparation imply the usual defined dynamic loading in the preparation process. At the same time disturbing macroscopic air inclusions are expelled from the test material by the exterior forces.

• the yield moment
• the moment of fracture
• a viscosity equivalent
• an equivalent of the modulus of torsion
• the elastoviscous and viscous proportions and
• at least three parameters

of fresh mortar in dependence on the water/dry mortar ratio, on the rest period and/or the reaction time and on the absorbing capacity of the plaster base. A further evaluation of the various experiments by means of an efficient software makes it possible to determine the material-specific parameters of the fresh mortar and to identify significant components of the mixture. With a view to minimising the experimental expenditure the flow diameter acc. to DIN-EN 459 may serve as orientation.

The RHEOTEST^Ò RN enables

• an objective qualitative and quantitative assessment and characterisation of material and workability properties of plaster mortar, structural mortar and similarly textured materials to be made.

In the production of building materials, especially of dry mortar, it is employed in the fields of

• quality control, particularly in connection with variations of mix designs
• complaints concerning quality

In the development and research of building materials it may be used for

• the characterisation of particular components of mixtures in the framework of synthesis and analysis.

The whole spectrum and the versatility of mortar building materials is taken into consideration by the use of further sensors.

RHEOTEST is a registered trademark of RHEOTEST Medingen GmbH. All other names of products, services and companies may be trademarks or registered trademarks or service marks of its owners.