The High Coast Bridge is one of the world´s longest suspension bridges. The
waterproofing and
pavement for this bridge had to be chosen with care. A lowest average
temperature of -20°C, a minimum
temperature of -40°C and a maximum temperature of +30°C have been recorded in
this reigon of
Sweden.
To be able to recommend the most suitable system for the bridge, a research
project was started by the
Swedish National Road Administration as early as 1992. As a result of
research and testing during the
project period, a suitable system for the bridge was suggested by the Swedish
Road Administration in
1996.
The waterproofing and pavement system chosen for the High Coast bridge
consists of an epoxy
primer system, an SBS-modified bituminous sheet layer, coarse aggregate
mastic asphalt with SBSmodified
bitumen and split mastic asphalt with SBS-modified bitumen and fibres.
Various waterproofing and pavement producst and systems were tested in the
research project, both
separately and in different combinations for evaluation.
Laboratory testing was performed at the Swedish National Road and Transport
Research Institute
(VTI), starting in 1992. Testing covered characteristics and performance of
the various products and
systems at low and high temperatures. Important parameters studied for total
built-up systems included
adhesion (to steel deck and between layers), shear and sliding resistance.
Systems with SBS-modified bituminous sheet (3.5 mm thick), SBS-modified fine
aggregate mastic
asphalt (4 mm) and conventional fine aggregate mastic asphalt (4 mm) were
compared.
In 1993, eight different systems were laid on a steel bridge at Pitsund
(further north than the High
Coast Bridge) for evaluation on site and laboratory testing at VTI.
Fatigue tests of the entire waterproofing and pavement system were performed
for four possible
systems and the reference system at the Otto Graf Institute (FMPA) in
Stuttgart. Testing was performed
in accordance with the German ZTV-BEL ST-92 Dauerschwellbiegeprüfung, but
at temperatures from
-30°C to+3°C.
The public procurement was completed in July 1996. The system was laid during
late summer and
autumn of 1997.
Quality control testing was performed. Samples of all products used were
taken during work on the
bridge.