This report gives details of the construction of a full-scale road experiment to study the performance of a polymer modified bitumen emulsion binder, surfix 80, in surface dressings. The experiment incorporates control sections with cutback bitumen and cationic 70 per cent bitumen emulsion binders. In addition to conventional dressings with a single layer of single sized (14 mm) chippings, sections of "rack-in" surface dressings are included in which the application of the 14 mm chippings was immediately followed by an application of 6 mm chippings. The performance of the surface dressings is being studied by assessments of chipping retention and degree of fatting using a widely accepted visual inspection technique and by monitoring changes in binder viscosity and friction properties - the latter by means of scrim and surface texture depth measurements. In handling and application the surfix 80 binder was found to be similar in behaviour to conventional bitumen emulsions. After 12 months in service all the experimental sections, including surface dressings with cut back bitumen and cationic bitumen emulsion, are in the "very good" category of performance. (author/publisher)
Abstract