ABSTRACT
The very fine component of the aggregate is called filler. Although the graded aggregate will normally contain some material of this size it is usually necessary to provide additional filler in the form of limestone dust, pulverised fuel ash, hydrated lime or ordinary Portland cement. Bituminous materials consist of a graded aggregate bound together with bitumen. In addition, the mixture contains a small proportion of air. Bitumen is a complex colloidal system of hydrocarbons and their derivatives which is soluble in trichloroethylene. The usual approach to the determination of the constituents of a bitumen is through the use of solvents. An emulsion is a two-phase system consisting of two immiscible liquids, one being dispersed as fine globules within the other. A bitumen emulsion consists of discrete globules of bitumen dispersed within a continuous phase of water, and is a means of enabling penetration grade bitumens to be mixed and laid.
