Foamed Bitumen Structure

Abstract

Foamed bitumen is a binder of cold mix asphalt, a road material alternative of the conventional hot mix asphalt. Because of foamed bitumen properties are still not well defined, then the cold mix foamed asphalt performance is not interpreted correctly. It causes any research to unlock the understanding of foamed bitumen properties is necessary. This paper is therefore designed to open one of the important foamed bitumen propertis aspect, i.e. its structure. The foamed bitumen structures are explored based on theoretical study. It is studied in a general context, including foam behaviour, body structure, modulus, and rheology. It is deduced from the results that foamed bitumen can be included within the general foam family. Foamed bitumen composition, with both wet and dry foam formation, gives an indication that foamed bitumen behaviour complies with expected general foam properties. It can be concluded some general properties that are valid for general foam and which are also valid for characterising foamed bitumen. This includes foam quality categories, structure, modulus, and rheology. Category of Foamed bitumen quality can be approached by wet foam ranges between 52% and 87%, stable dry foam between 87% and 96%, and beyond 96% the dry foam becomes unstable. This quality category is adapted from foam in the general context.