Repairing bituminous joint sealing with WEBAC® 4101
A completely new sealing system for defective expansion joints has been successfully tested with the help of WEBAC on the HPP Cascade of the Daugavas river (the main Latvian stream with 40 m waterlevel), which was built in the 1960s.
The aim was to repair the vertical expansion joints between the sections filled with bitumen durably and cost-effectively. Divers had noticed that bitumen emerges from the bottom part of the joints. It was assumed that the bitumen had become brittle or so during the 40-year-long aging process. Actually it was not possible to repair the joint by filling it with bitumen. To minimize the damage it was decided to install a new joint on the water side while closing the old one. On the basis of very successful test results it was decided in 2000 to fill the new joint with the elastic epoxy resin WEBAC® 4101. This material stands out due to its high elasticity and excellent solidity. A 32 m deep vertical drill hole was made to make the joint. Then a cottoncoated hose and a perforated PE pipe were put into place. The actual injection was effected by means of an injection hose beginning at the lowest point of the water-filled joint. The injection hose was then moved bottom to top from injection level to injection level, injecting the material directly into the EP resin but not into the water which was to be displaced. This way the drill hole was filled entirely with the injection resin. In so doing, the counter pressure was observed at all times in order to gather information on the progress of the injection procedure under water. The filled hoses adapted to the drill hole course very well and allowed for a 100 % watertight sealing procedure. The new joint was examined by experts and the results were so convincing that the same procedure was implemented again on a different joint of the dam a year later. Between 2001 and 2002, about 8 tons of WEBAC® 4101 were used for this project.
This successful, unusual repair measure was implemented under the auspices of the managing company, whereas the official body for dam safety was the project manager. The main active participants of this reconstruction project were specialized regional companies and WEBAC, represented by our Latvian sales partner Plastima AT.