Current developments in performance testing of bituminous emulsions used in chip seals

Abstract

The use of bitumen emulsions in surface treatments has become prevalent due to advancements in emulsifier development, formulation techniques, and design of surface treatments. However, current practice for testing and selecting emulsion grades for chip seals remain mainly empirical, with little or no known relationship to the failures occurring in the field. The current practice appears to be more focused on quality control during the emulsion formulation process than on the in-service performance of the emulsions. Although significant progress has been made in developing performance-based test methods and specifications for hot mix asphalt binders, they cannot directly be adapted to emulsions used in chip seals. This paper carried out a literature review identifying common distresses occurring in chip seals, both during construction and in-service. Emulsion properties related to specific distresses as well as potential laboratory test methods for evaluating the identified emulsion properties were also identified. The information was used to propose a performance based testing framework for emulsions used in Southern Africa.