PU Injection Foam Resins
WEBAC® PURstop 1C
- Consolidation Line
Shaft sealing under pressurized water, Naples
After completion of a sewage pipe using the microtunneling method, there was a severe water ingress at one of the launch shafts (approx. 3 × 3 m) in the area of the pipe penetration, which was installed at a 90° angle in the shaft.
First, the water ingress had to be stopped quickly and temporarily. Then the leak could be permanently sealed. Sleeve pipes with a length of 3 meters were installed on the outside of the shaft, in the area of the pipe penetration. These were provided with an opening every 50 cm.
Injection with WEBAC PURstop 1C was carried out from below, starting at these openings. This allowed each sleeve opening to be injected with a defined amount of foam resin. During the injection process, a watertight PU veil formed around the leaking pipe penetration.
The progress of the injection was easy to observe – the decrease and cessation of water ingress into the shaft was clearly visible.
As it was not possible to perform patching of the pipe penetration inside the shaft in advance, foam resin leaked into the interior of the shaft. This was removed after the injection was completed, albeit under difficult conditions due to the confined space.
After the water had been effectively stopped, the launch shaft of the microtunnel boring machine could be permanently sealed; it has since served as an inspection shaft.
Products Used
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WEBAC PURstop 1C is a single-component, polyurethane-based injection resin with a catalyst. Upon contact with water, it reacts rapidly and expands vigorously, forming an elastic, adaptable foam that reliably stops water ingress. The reaction time can be adjusted using the WEBAC PURstop ACC 1C catalyst. It is suitable for sealing Foundation Pits, for solidification of loose soils, and for filling voids.
