Determination of settling tendency after n-days

The settling test is carried out to determine the settling tendency of bituminous emulsion stability during its storage. 

Settling tendency is the difference in water content of the top layer and the bottom layer of a prescribed volume of sample after standing for a specified time at ambient temperature. 

When conducting the test in accordance with CEN EN 12847 (2009), depending on the water content determination method, one or four 500 ml stoppered glass graduated cylinders are filled with emulsion and allowed to stand undisturbed for w-days, usually 7 days. The samples are tightly stoppered so that there is no water loss. 

After the standing period of 7 days, a quantity of approximately 55 ml of emulsion is carefully drawn from the upper part of the cylinder. The quantity collected is placed in a beaker to determine the water content (A). Then, a quantity of approximately 390 ml is removed from the cylinder. The remaining quantity of emulsion, approximately 55 ml, is stirred and drained into a second beaker to obtain a second test portion for water content determination (B). 

The water content is determined in accordance with CEN EN 1428 (2012) or CEN EN 1431 (2009) from the two emulsion specimens collected from the two different positions. The settling tendency, ST, of the test sample, expressed in mass percentage, is determined by the difference (A - B). The settling tendency is often also called long-term storage stability. 

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