Rheology
A rheometer measures the flow of fluids and deformation of solids under various conditions of stress and strain. It characterises material behaviour such as yield stress, kinetic properties, viscosity, modulus, creep and recovery. Most rheometers belong to one of three categories, the rotational rheometer, the capillary rheometer, and the extensional rheometer. The most commonly used is the rotational rheometer, which is also called a stress/strain rheometer.
Rheology is the most sensitive method for polymer characterisation because flow behaviour is responsive to molecular weight and molecular weight distribution. Rheological measurements allow the study of the effects of chemical, mechanical, thermal and additive treatments on polymer processes.
Rheometers are also used to measure the rheology of semi-solids, suspensions and emulsions, in industries such as pharmaceuticals, foods, cosmetics, and consumer products. These measurements can help predict product shelf life of under various stress conditions. Rheology measurements are useful in following the course of a chemical reaction. Such measurements can be used for quality control or to monitor a manufacturing process.
Click here to contact usAsphalt Dynamic Shear Rheometry
Chemically, asphalt is a mixture of polar and non-polar complex organic molecules. The microstructure of these molecules tends to govern asphalt’s physical behaviour. Since chemical knowledge is limited, asphalt is most commonly described by its physical properties that are directly related to field performance.
An important physical test is Dynamic Shear Rheometry (DSR) used for testing medium to high temperature viscosities. The test is conducted between 46 C and 82 C. The basic DSR test uses a thin asphalt binder sample sandwiched between two plates. The lower plate is fixed while the upper plate oscillates back and forth across the sample at 1.59 Hz to create a shearing action. These oscillations are meant to simulate the shearing action corresponding to a traffic speed of about 90 km/hr. The DSR is able to determine the total complex shear modulus as well as its elastic and viscous components.
The standard dynamic shear rheometer test is AASHTO TP 5: Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer (DSR)
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