The performance evaluation of slow-setting anionic bitumen emulsions and their residues

Nomashaka Hawes, CSIR


Surface treatments are the most commonly used bituminous binder products for roads in Southern Africa. This is mainly because with comparison to other types of surfacing are found to be inexpensive. Although there have been great strides in the improvements of bituminous emulsions, where the ever changing or expansion in the variation of their formulations plays a great role in that development.

The current testing methods of emulsions are empirical and show very little in their in-service. The quality of the bituminous emulsion is affected by many factors, such as particle size, base binder and formulation ingredients, which in turn affect their in-service performance.

There are several test methods that have been suggested and developed in the possible evaluation of bituminous emulsion rheological properties with relation to the in-service conditions. The performance based methods that were found to correlate with the failures experienced by the slurry sealed pavements were identified and verified, using the standard bituminous emulsions already used in industry of South Africa.

The primary objective of this study was to evaluate the possible effects of emulsifiers have on the rheological properties of the emulsion and its residue. These are during storage and in-service of anionic slow-setting bituminous emulsions used in slurry seals.

This was studied by evaluation of their change in viscosity through storage. The strain resistance of their residue through determining their elastic resistance and non-recoverable (Jnr) compliance. The evaluation of the fatigue resistance was carried out by the prediction of failure using time-temperature superposition (TTS) principle. All performance evaluation was carried out using the readily used dynamic shear rheometer (DSR) in industry.

Results showed the performance of the emulsion and residue in-service may be observed with limited observation on the effect of the varying emulsifiers used.