Abstract
A medium-scale earthquake happened to cause severe damages on the asphalt facing zone of an earth-dam; many cracks appeared on the slope surface especially near the crest and on the bottom surface of the reservoir, though the dam body itself was scarcely damaged. Due to viscous natures of bitumen, asphalt mixtures are in general highly flexible, accompanying much stress relaxation, and can follow large deformation without serious damages, as compared with cement mixtures. It is well known, however, that under low temperature in winter season and under high rate of cyclic loading during earthquake, asphalt mixtures are often to be damaged by reducing flexibility due to their temperature and strain rate dependencies. In this paper, new asphalt bitumen is developed, from view points of visco-elasticity and sensitivity to temperature, in order to improve flexibility under low temperature, and also to have sufficient resistance against flow under high temperature. Several laboratory tests are carried out to investigate mechanical properties of the asphalt mixtures made with this new bitumen, and the results are compared with those of usual straight asphalt mixtures to verify improvement of high flexibility and stress relaxation, and of high ductility under low temperature and cyclic loading conditions.
