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Bonds with heat of the textiles

Views of the site

Reference:

More information on the project of the deep excavation using slurry walls, are provided here

The photos are from a project in the city of Patras, Greece. The project consists of a
two sub-storey parking below an entertainment complex. After the completion of the
deep excavation, geosynthetics were used for the water isolation of the excavated
area. The Geomembranes used (yellow color), are bonded together with some kind of
glue. It is very important that the two parts are perfectly bonded using thermal
bonding. This is a very delicate procedure since imperfections in the bonding could
lead to water intrusion. Photos of the thermal bonding procedure are provided.
Below are briefly described some details in the execution of thermal bonding and
Construction Quality Assurance (CQA).

Methods to check the quality of work.

There is a very thin copper wire along the joining. This wire must not have
contact with the air if the work is done properly. So at the two-ends of the wire
a source (like a battery) is installed. If there is a point were the wire comes in
contact with air, then a sparkle comes out and the spot is indicated to restore
it.
A pump presses air between the bonds. If the air pressure falls, this mean that
in a place the textiles are not bonded perfectly.

Materials

In the specific site, three kind of geosynthetics were used (check the photo above)
forming a "geocomposite":

In the outside, in contact with the concrete a tough plastic was used for the
protection of the other two PVC (dark green) typically called Geoglass
In the middle, a white colored geotextile (Polyfond type) is used to protect the
geomembrane.
On the top, a geomembrane (yellow), is used as a hydraulic barrier.