Chip seals or surface dressings are a very cost effective way to restore the skid resistance and water-proof aged wearing courses. Classically, chip seals consisted of a layer or two of single-sized aggregates, held in place by a tar or bitumen binder. Their spray application is made at high temperatures in the form of a fluxed or fluidized binder, or at lower temperatures as an emulsion containing the modified binder dispersed as fine particles in a treated water solution. More recently, the binder of choice is a polymer modified bitumen. Resulting from a cooperative research between Elf Antar France and LCPC (French Roads and Bridges Administration Laboratory) a new concept of in situ cross-linking of SB block co-polymer in bitumen has been developed (Styrelf). A short discussion on the basic principles of chemical polymer bitumen modification and results obtained by means of up to date physical devices are presented. Comparison between standard fluidized bitumen, Styrelf 103 and Styrelf 205 emulsion is made on elasticity under high shear conditions, the spectrum of cohesion versus temperature, and high/low temperature behavior on stabilized binder. (A) The German title of this article is: Bitumen, Modifiziert mit Chemisch-Vernetztem Polymer, ein Mittel fuer Wirschaftlich-Effektive Sanierung der Strassen.
Samenvatting