Viscosity test by efflux or cup viscometers

The efflux or cup viscometers are used to determine the viscosity of bitumen emulsions and 

During the test, a viscometer cup is filled with a certain quantity of liquid bituminous binder and is left for a sufficient time until reaching the required temperature (usually 40°C, 50°C or 25°C). Then, the bituminous binder is effluxed through an orifice of various diameters (typically 2, 4 or 10 mm) and length (depending on the viscometer), until a required volume (50, 60, 100 mm or other depending on the viscometer) is collected in a graduated flask or cylinder (receiver) and the efflux time (t) is recorded in seconds. 

The efflux time, indirectly, is a measure of viscosity. However, the efflux time (t) may be converted to dynamic viscosity (q) if the density of the liquid (p) and the constant of the cup viscometer (C) were known (q = x p x C). Similarly, the kinematic viscosity (v) may be determined, if the constant of the cup viscometer (C) was known (v = f x C). 

The Saybolt Eurol viscometer is mostly used in the United States and the testing procedure is described in ASTM D 88 (2013), ASTM D 7496 (2011) (for emulsified asphalts), ASTM E 102 (2009) (for bituminous materials at high temperatures) or AASHTO T 72 (2010). 

The testing procedure when the Engler viscometer is used is described in ASTM D 1665 (2009). 

---