2 3 4 5 6

Expert Rating of Field Performance

2。5 yrs 5 yrs

Figure 9。 Lab results for heat resistance (left) and GPC polymer degradation (right) as compared to the expert assessment over a time period of five years

12。5 13。0 13。5 14。0 14。5 15。0

Analysis Time [min]

Figure 10。 GPC-chromatograms of polymers in the BEJ binder; segregation in container of filling material (left); BEJ filling material C with different quality at different installation locations (right): NW good reference, AG overheated, TI smaller polymers

GPC, as required by the guidelines [7], proved to be an extremely valuable tool。 It allows determining the polymer decomposition due to the installation process, hence providing a means of verifying heat sensitivity of the most common polymers in the binder and deter- mining thermal damage of the binder。 Figure 10 shows how GPC allows detecting segrega- tion of the polymer in the container of the filling material as well as differences in material and installation quality。 In the diagram to the right, "System C: NW" shows the  highest

content of polymers with largest molecule size。 As compared to this, the largest peak in case of "System C: TI" is much smaller and a little bit shifted to the right。 This indicates that the composition of this presumably same binder was most probably not identical。 In case of "System C: AG" the main peak is not shifted to the right, but much smaller and the second peak (which is also not shifted) becomes significantly higher。 From this, one would conclude that the material was originally identical to the "System C: NW" but had suffered considerable overheating and molecular damage (smaller size of the molecules)。

5 Behavior of wide bituminous plug expansion joints after heavy traffic

5。1 MMLS3 field testing of wide BEJs on a multi-span bridge

In some special cases it may be necessary to install BEJs with a width exceeding 500 mm。 This may hold for multi-span bridges where the construction requires merging two plug joints (Fig。 11) or in case of BEJ replacement, when the locally cracked or deteriorated pavement needs to be cut-off on the side of the trench。 In order to account for such situa- tions, condition and performance of ten special BEJs were investigated after heavy traffic loading and weathering, immediately prior to demolition of the relevant bridge structure。

The plug joints were located on a series of 80 m span slope-side bridges of the A2 mo- torway in the Mediterranean southern part of Switzerland (TI,2 in Fig。 8) with a traffic vo- lume in each direction of 30'000 vehicles per day。 The width of these plug joints ranged be- tween 750 mm to 1'370 mm, thus considerably exceeding the standard width of 500 mm specified by Swiss guidelines [7]。 The horizontal design movement was between 8 to 48 mm as indicated in Figure 11。

Figure 11。 Wide BEJ systems, northbound MMLS3 testing sites and 7 year visual performance on Motorway A3 in southern Switzerland。

The goal of this study was to evaluate long term performance over and after a loading pe- riod of seven years, the assessment of specific refurbishing and repair actions undertaken immediately before the observed loading period as well as the investigation of the remain- ing rutting potential before demolition of the bridge。