![]() ![]() ![]() When pumping asphalt, the startup torque required to get the pump going initially suggests that a second viscosity test at a much lower rotational speed makes sense. However, this straightforward single-point test does not provide the complete picture for asphalt flow behavior. Record the viscosity value, make sure that it falls within prescribed maximum and minimum limits, and then report whether the number passes or fails. The standard test method for pumpability, according to ASTM D4402, is to use a regular viscosity (RV) torque rotational viscometer at 20 rpm or a low viscosity (LV) instrument at 12 rpm. An important concept, sometimes forgotten, is that a material’s viscosity is not a single-point measurement, but often depends on a number of factors. This article reacquaints the reader with the basic concepts and terminology for viscosity and addresses techniques to quantify it. The bottom line is to come up with ways to measure viscosity so that you can quantify whether a material will flow the way it needs to. For handlers of all materials that flow, either while being processed or in an end-use, it is important to think about the materials’ flow characteristics. To be brief, viscosity is resistance to flow. What you are really measuring is the change in volume as the tube has a constant cross area V=Area time height, and you mark the height in units of temperature.Most engineers know what viscosity is, but may have trouble explaining it. For example, if you know how the density of mercury (or alcohol) changes as a function of temperature, you can construct a thermometer where you measure the height of the column. No, you actually measure something else that changes as the temperature changes. To measure the density of something you measure it's mass and volume, and then take the ration (d=m/v).ĭoesn't a thermometer measure temperature, an intensive property? You usually measure extensive properties. Not directly, as they change as the system changes.ĭo you measure intensive of extensive properties? But a Gas is compressible, and fills the container, so density alone can not indicate what the gas is.Ĭan extensive properties be used to identify what a substance is? For example, if a substance is incompressible (solid and liquid) the density is considered constant at a given temperature and pressure, and can be used to identify a substance (gold has a density of 19.3g/ml, and if a gold ring does not have that density, it is not pure gold (note the inverse is not necessarily true, just because the density is 19.3g/ml does not mean it must be gold, but that it could be gold). If you add one gallon of gasoline at 25 0C to a car's gas tank that contains a gallon of gasoline at 25 0C, you double the mass, volume and distance you could drive (energy of the gas), but the temperature does not double, and the density is the same.Ĭan intensive properties be used to identify what a substance is? Mass and Volume are extensive, while temperature and density are intensive. What is the Difference Between Extensive and Intensive Properties ?Įxtensive properties depend on the amount of matter (extent of the system), while Intensive do not depend on the amount of system. Examples include the state of matter, odor, color, volume, denisty, melting point, boiling point, temperature, electrical conductivity. Physical Properties describe the physical state of matter. Note, these solvents must not mix with each other (so one phase must be like an oil, and the next like water, as oil and water do not mix), and the particles will aggregate in the solvent whose densities are closest to them (they sink in lighter density solvents and float in heavier density solvents). In fact, we can sort plastic particles by placing them into different solvents of different densities, as shown in this Youtube. \): Density of common plastics Plastic Symbol ![]()
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