1. EMPA Duebendorf, Structural Engineering Research Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland.
2. Belgian Road Research Centre, Asphalt Pavements, Bituminous Applications and Chemistry Division, Boulevard de la Woluwe 42, B-1200 Brussels.
3. University of Twente, 7511 ZC Enschede, Hoge Bothofstraat 72, Netherlands.
4. Professor, EMPA Duebendorf, Structural Engineering Research Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland.