11 - Use of Cationic Bitumen Emulsions in Skid-Resistant Surface Dressings on Main Roads and Motorways

Abstract

Abstract Skid-resistant surface dressings resistant to the high shear rates existing at the surface of main roads under fast traffic are obtained by using cationic emulsions as binder. The best technique for this purpose is to lay double-layer surface dressings. A number of important factors have to be taken into account to succeed and to ensure the maximum durability for the surfacing. In addition to the precautions to be taken for ordinary surface dressings, such as cleanliness of the old road surface, control of the proportions of emulsion and chippings, the following requirements exist: a. a lower proportion of emulsion for the first layer than for the second; b. a loose distribution for the first layer of chippings; c. a difference of size between the first and second layer of chippings, i.e. 10–14 mm and 4–6 mm respectively; d. no rolling of the first layer; e. use of fast-breaking viscous cationic emulsions; f. chippings as cubical as possible. Examples of double-layer surface dressings laid in France on main roads and motorways will be given.