Determination of water content in bitumen emulsions - azeotropic distillation method

6 Determination of water content in bitumen emulsions - azeotropic distillation method 

This test determines the water content in a bitumen emulsion by azeotropic distillation method. Azeotropic distillation refers to the technique of adding another component to generate a new, lower-boiling azeotrope that is heterogeneous (e.g. producing two immiscible liquid phases), for example, xylene and water. Azeotrope is a mixture of two or more liquids in such a way that its components cannot be altered by simple distillation. The azeotropic distillation method, for simplicity, is referred to as distillation method. 

The water contained in a bitumen emulsion or in the graded bitumen, if such a case arises, is distilled by means of a carrier vapour from a water-immiscible solvent-carrier liquid. 

A sample of bitumen emulsion is placed in a round bottomed flask of 500 ml so that after distillation to receive 15 ml to 25 ml of water. An approximate amount of 100 ml of solvent carrier 

The round-bottomed flask is assembled in the distillation apparatus, which includes a receiver (trap) and a condenser. The distillation continues until no increase of the water volume in its receiver is observed. The percentage of water (w) contained in the bitumen emulsion is calculated by the following relation  

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CEN EN 1428. 2012. Bitumen and bituminous binders - Determination of water content in bitumen emulsions - Azeotropic distillation method. Brussels CEN. 

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