10 Effective Measures for Enhancing the Waterproofing of Diaphragm Walls

Diaphragm walls are not waterproof structures. It is common for moisture and small water leaks to appear during the excavation of the enclosure, either through joints, connections, or the concrete itself. This is reflected in international regulations, such as the European Standard EN 1538: ‘Execution of special geotechnical works: diaphragm walls.’

If the project requires a completely watertight finish, additional work needs to be planned. However, in most cases, the level of waterproofing provided by diaphragm walls is sufficient.

Nevertheless, if diaphragm walls are not completely watertight, what measures can be taken to improve their waterproofing? Here are some key factors to consider:

  1. During the design phase, try to minimize the number of joints between panels, as joints are the most susceptible sections to moisture and leaks.
  2. Adhere to the excavation verticality tolerances specified in the regulations and typical project specifications (usually below 0.5-1.0%) to ensure alignment of the diaphragm wall.
  3. Control the characteristics of the drilling fluids, whether bentonite or polymer-based, throughout the execution process, especially the sand content before pouring the concrete.
  4. Thoroughly clean the bottom of the panels to avoid excessive sediment accumulation at the base of the diaphragm wall.
  5. Select the appropriate joint type based on project characteristics such as geometry, thickness and depth of the wall, soil type, final excavation level, and intended use of the interior space.
  6. Ensure strict control over the installation and removal processes of joint formwork.
  7. Adhere to the design and assembly specifications for reinforcement cages, particularly the spacing between bars, as well as the distances between cages, joint formwork, and panel ends.
  8. Use high-quality, homogeneous, workable, self-compacting, and segregation-resistant concrete.
  9. Carry out continuous and efficient concreting, with the number of Tremie columns adapted to the panel’s plan length, and always keep the pipe submerged in the concrete.
  10. Perform additional waterproofing work if required by the project, such as the construction of an interior lining wall or injections.

In conclusion, this article offers valuable guidance on improving the waterproofing of diaphragm walls. Although diaphragm walls are not inherently waterproof, incorporating the 10 recommended measures can greatly enhance their ability to resist moisture and water infiltration. By focusing on aspects such as joint design, drilling fluid control, reinforcement selection, and high-quality concrete, construction practitioners can significantly enhance the watertightness of diaphragm wall structures. Implementing these strategies will help mitigate potential issues associated with moisture and leaks, ensuring a higher level of waterproofing in construction projects.