Description
Paving on Steel structural Bridges (SSB) remains as one of the biggest unsolved problems of China Paving Industry.
The research in laboratory saw the evident improvement in almost all the hot mix design targets, especially the permanent deformation. By adding crumb rubber to modified asphalt, the high temperature stability is enhanced to a very high level. If use modified asphalt exclusively, the asphalt must be very hard and has bad workability to reach the same level. Based on the 80-mesh rubber, the reasonable rubber content was decided by a set of parallel tests. Of course, the effect of rubber on different gradations, from dense graded to porous graded mixes, were tested.
To value the in-site performance of the laboratorial results, a demonstration project was initialized in May, 2001. The project was opened to traffic in August, 2001. The bridge (about 1000 meters long) locates in a very important freight channel. the average daily traffic on the 4-lane highway is about 20000 vehicles. And because of the serious overloading, the cumulated Equivalent Standard Axle Loads (12 years) are about 140 millions. After two-year usage, the pavement remains good performance. Permanent deformation reaches only 1~5mm, and there is no obvious other deteriorations.
