Description

Concrete rheological properties need to be properly measured and predicted in order to characterize the workability of fresh concrete, including special concretes such as self-consolidating concrete (SCC). The Concrete Rheometer is capable to characterize the static yield stress, the dynamic yield stress and plastic viscosity of the concrete. A high static yield stress is desirable because it reduces formwork pressure and increases the resistance to segregation. But for ease of pumping, placement and self-consolidation, a low dynamic yield stress is necessary. The dynamic viscosity provides cohesiveness and reduces segregation when concrete is flowing. Thus, by determining the dynamic flow curves of concretes mixtures and optimum balance between ease of flow and resistance to segregation can be realized. These types of determinations cannot be done using conventional slump-based tests.

The Concrete Rheometer is composed of a container to hold the fresh concrete, a driver head supported on a frame with an electric motor and torque meter, a four-blade vane and a laptop computer to operate, record the torque  and calculate the flow curve parameters. The size of the container and vane are selected based on the nominal maximum size of the aggregate. A multiple blade “Carrousel” vane is also available for a container for maximum aggregate size of 13 mm for more accurate and stable measurements on materials like high flow self-consolidating concrete (e.g. slump flow > 600 mm), flowable mortars or grouts (e.g. self-leveling), mortars for 3D printing, etc.

Two types of tests can be performed: stress growth test at a constant slow speed where the maximum torque measured is used to calculate the static yield stress; and the flow curve test to determine the dynamic yield stress and the plastic viscosity (Bingham parameters).

SPECIFICATION

Parts of Rheometer kit involves:

• Motor drive/torque meter unit
• Power cord for motor drive unit
• Base frame
• USB cable RHM-3012
• Laptop computer with software
• Software on CD-ROM
• User manual
• Carrying case for laptop computer
• Carrying case for Rheometer
• Containers and vanes for different NMSA Container, four-blade vanes for Nominal Maximum Size of Aggregate (NMSA) 13 mm 19 mm 25 mm 32 mm
• Carrousel Vane
• 30,000 centistokes silicone oil for verification of instrument (25 L or 19 L pail)
• Motor type: Integrated Servo Motor
• Accuracy: ±0.1 %
• Resolution: 0.001 Nm
• Minimum Torque: 0.01 Nm
• Peak Torque: 90 Nm for not more than 2 seconds
• Continuous Maximum Torque: 32 Nm
• Power Supply: Input of 100-240 VAC 50-60 Hz – 3.5A.
• Digital Calibration can be performed by user at any time
• Performs static stress growth and dynamic flow curve tests
• Software computes static yield stress, dynamic yield
• Stress, and plastic viscosity in fundamental units
• Motor drive dimensions: 11 x 11 x 43 cm
• Motor console weight: 7.5 kg

DIMENSIONS & WEIGHTS

• L x W xH: (0.7 x 0.6 x 0.3) m
• Weight: Approx. 50 kg, including motor drive, base frame, vane, power supply and cables