Bitumen emulsion tests

The basic tests conducted on bitumen emulsions as required by CEN EN 13808 (2013), ASTM D 2397 (2012) or AASHTO M 208 (2009) are described in the following paragraphs. For the list of tests on bitumen emulsions, see also Tables 3.13 and 3.15. 

Apart from the tests performed on bitumen emulsions, tests are also performed on the residual bitumen contained in the emulsion. The tests on the bitumen residue (see Tables 3.14 and 3.15) have been described in the previous paragraphs of this chapter. 

The residual bitumen for properties determination is extracted by distillation procedure. The azeotropic distillation (by means of a carrier vapour from a water-immiscible solvent-carrier liquid) is used only for the determination of the water content in bitumen emulsion. 

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Sampling of constituent materials is carried out in the central mixing plant or upon delivery of the materials on site. Aggregate testing procedures are the same as those for hot mixtures. Bitumen emulsion testing, as well as tests on the recovered bitumen, follows the requirements and test methods specified in the standard used. 

J. L Marchal, P. Julien, N. Boussad, Bitumen Emulsion Testing Towards a Better Understanding of Emulsion Behavior, ASTM Symp. Asphalt Emulsion, 1990. 

In some cases, minimal effort is required for the demulsification process. For example, in field tests, adequate separation of a bitumen emulsion could be achieved without the use of demulsifiers by raising the temperature of the emulsion to 190 T and providing 24 to 48 h of residence time in quiescent storage tanks. However, proper selection of demulsification chemicals is essential when treating the emulsions in conventional equipment on a continuous-flow basis. 

In 1985, the transportation and the combustion research teams at INTEVEP combined their efforts and a preliminary round of combustion tests was carried out (10,11). By 1986, it was established that the bitumen emulsion could be used as an efficient fuel (60, 61). 

Emulsion storage stability is quickly determined by the 24 h settlement test (see Section 4.20.13). The size of bitumen globules, as well as their size distribution, can be determined using electronic microscopes or electronic apparatuses for sieve analysis. A quick and far less costly method to determine the suitability of the bitumen emulsion in road... 

The pendulum (Vialit) test, according to CEN EN 13588 (2008), determines the cohesion of any bituminous binder (pure, modified or fluxed). Cohesion is one of the measures of the performance of the bituminous binder, particularly modified bitumen or bitumen recovered from bitumen emulsion. It is important to use binders that have a sufficient level of cohesion according to the level of traffic to be supported. 

Laboratory tests and properties of bitumen and bitumen emulsion... 

This chapter provides a description of all laboratory tests performed on both conventional and modified bitumen. Additionally, the laboratory tests performed on bitumen emulsions are also described in brief. 

The rotational paddle viscometer is used when, rarely, the apparent viscosity of a bitumen emulsion needs to be determined. A detailed description of the viscosity test by rotational paddle viscometer can be found in ASTM D 7226 (2011). 

In the case of fluxed bitumen, the test is performed on the binder containing fluxant or on the binder from which the solvent has been removed. For bitumen emulsions, the test is carried out on the residual binder obtained after recovery. 

This test method determines the specific gravity and density of bituminous binders, apart from bitumen emulsions, at 25°C 0.2°C using capillary-stoppered pycnometers. The method may be performed at other temperatures, but when doing so, the density values of the water or other liquid used should be determined. 

This test is performed in order to determine the bitumen particle polarity of the bitumen emulsion and, hence, the type of emulsion (cationic or anionic). 

During the test, two steel plates (electrodes) are dipped into the bitumen emulsion and a direct electric current of 8-10 mA is passed through the plates. After approximately 30 min or when the current drops to 2 mA, whichever is achieved first, the bitumen deposition on the electrodes is observed. If bitumen deposition appears on the negative electrode (cathode), the emulsion is cationic. Otherwise, the emulsion is anionic. 

This test determines the breaking value of the cationic bitumen emulsion. 

The test determines the mixing stability of bitumen emulsions with cement. It applies to overstabilised cationic bitumen emulsions and to slow-setting and overstabilised anionic bitumen emulsions. 

This test determines the penetration power of bituminous emulsions, through a reference filler, and is applicable to low-viscosity bitumen emulsions and is conducted at normal laboratory temperatures (18°C to 28°C). 

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. 

This test method involves a rapid quantitative determination of the residue in bitumen emulsion using a moisture analyser. It is applicable to all non-solvent-containing emulsion types, anionic, cationic, non-polymer-modified or polymer-modified bitumen emulsions. 

This test method is for the quantitative determination of residual binder and oil distillate in bitumen emulsions for specification acceptance. The method is used to obtain residue and oil distillate for further testing. 

Figure 4.14 Apparatus for distillation test of bitumen emulsions. (Reprinted from ASTM D 6997, Standard test method for distillation of emulsified asphalt. West Conshohocken, Pennsylvania, US ASTM International, 2012. With permission [ ASTM International].)...

This test determines the efflux time of a bitumen emulsion, using an efflux viscometer. The efflux time is the time of efflux of a given quantity of the emulsion through an orifice of a... 

The test for bitumen emulsions is carried out in accordance with CEN EN 12846-1 (2011),... 

The Saybolt viscometer may also be used when testing bitumen emulsions and the test is carried out according to ASTM D 7496 (2011). 

This test method determines the quantity of coarse particles of binder present in a bitumen emulsion by utilising sieving and, from that, storage stability. 

The above test method is similar to that specified in ASTM D 6933 (2008). The main difference is that a 0.850 mm sieve instead of a 0.5 mm sieve is used. Additionally, the temperature at which the sieve test is performed is related to the viscosity of the bitumen emulsion. For those materials whose viscosity in Saybolt Furol seconds is 100 s or less at 25 C, the test is performed at ambient temperature. For those materials whose viscosity is greater than 100 s at 25°C and those whose viscosity is specified at 50 C, use a test temperature of 50 C 3°C. 

This test determines the adhesion of a cationic bitumen emulsion coated onto aggregate when immersed in water. The adhesion is defined as the ability of a binder to wet the surface of an aggregate and to remain bonded over time. Adhesivity is the qualitative assessment of the measurement of the adhesion. 

Assessment of the coating of the total aggregate surface area by bitumen emulsion is carried out in both test samples, using the grades good, fair or poor. 

The demulsibility test is used to identify or classify a bitumen emulsion as rapid setting (RS) or medium setting (MS) by measuring the amount of bitumen that is broken from the bitumen emulsion. This is obtained by utilising specified amounts and concentrations of calcium chloride solution for anionic bitumen emulsions and dioctyl sodium sulfosuccinate for cationic bitumen emulsions. 

Sample conditioning is required before testing. Bitumen emulsions with viscosity testing requirements of 50 C are heated to 50 C 3 C and stirred, before testing, to achieve... 

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