Bitumen Emulsions Test Procedures 3h5b1t

Bitumen Emulsions Test Procedures Bitumen emulsions are subject to their own test procedures. Some of the tests used for determining their properties are as follows:

Consistency: Also known as the Engler Viscosity test, this measures the rate of flow of the bitumen emulsion at 25°C. The emulsion is heated to 25°C and poured into a standard container. The time taken by 200mL of emulsion to through a standard orifice at the bottom of the container is measured.

Water Content test: determines the weight percent of water in an emulsion. This can be performed by Dean and Stark distillation or Karl Fischer titration. In the Dean and Stark distillation, a sample is heated with a solvent that is immiscible with water. During the distillation process, the solvent and the water are separated in a trap so that the amount of water can be measured. In the Karl Fischer water content method, the emulsion is dissolved in a solvent and titrated with a Karl Fischer reagent, which reacts with the water in the emulsion. The amount of Karl Fischer reagent consumed is used to determine the water content of the emulsion.

Sedimentation test: indicates the extent to which the components of an emulsion sample will separate during storage. Samples are taken from the top and bottom of a 500mL sample that has stood undisturbed for three days. The samples are tested for water content. The difference between the water content of each sample is an indication of the degree to which sedimentation has taken place.

Stone Coating Ability and Water Resistance test: it is essential that a bitumen emulsion stands up to the action of being mixed with aggregates, coat them as completely as possible and not be washed off by any water that may fall on it once the mixing is completed. This test shows the extent to which a sample meets these requirements. It involves coating a sample of aggregate with emulsion, spraying it with water until the water coming from it is clear. The coating on the sample is assessed.

Particle Charge test: identifies the charge on the bitumen particles in an emulsion. A positive and a negative electrode are left in a sample of emulsion for half an hour. If there is bitumen deposited on the negative electrode at the end of the test the emulsion is cationic; if bitumen is deposited on the positive electrode, the emulsion is anionic.

Sieve Residue test: shows the presence of coarse binder particles in the emulsion. These particles may be in the form of relatively large globules or strings and may indicate instability or result in poor coating performance or clogging of equipment. The sample is strained through a 150μm sieve and the percentage mass of emulsion retained on the sieve is calculated and reported as sieve residue.

Residue from Evaporation test: indicates the percentage mass of binder present in an emulsion. An emulsion sample is heated so that water and other volatile components are evaporated. Residue from evaporation is calculated from the mass of the sample and residue after evaporation.