Rehabilitation Of Chekka Tunnel

Client: Council for Development and Reconstruction
Location: Northen Lebanon
Value: $21,134,769.63

The Chekka Road Tunnel was constructed in 1977 and comprises two parallel tubes accommodating three traffic lanes each. Each tube is 400m long and 9m wide, having an internal diameter of 12m.

The works are subdivided into following:

• Exterior and Interior surface repair: A total surface of almost 18,500m2 constituting of two shells and four frames as well as an external surface which is rehabilitated as follows:
  – Internal scaffolding – Ultra high pressure water jet of all surfaces
  – Cracks sealing and injection by epoxy resin with special pumps
  – Removal of deteriorated concrete and replacing it by reinforced mortar
  – Curing reinforcement by an anti-corrosion
  – Protecting the cleaned and repaired surface by a spray able waterproofing membrane master seal-345
• Construction of internal shotcrete jacket and a waterproofing membrane
• Local concrete repair and construction joints repair
• Slope stabilization
• Water basin and drainage channels
• Tunnel street lighting and traffic safety

The original refurbishment design and the tender documents called for a PVC sheet membrane for waterproofing and a final inner lining of 25cm of cast-insitu concrete.

This would impose a reduction of the interior tunnel profile, unless the original concrete lining was demolished. This would impose a technically difficult solution to implement as well as create a long construction programme.

For this reason the main contractor for the refurbishment was interested in considering an alternative technical solution which was both cost-effective and time saving.

The composite liner with the sprayable membrane proved to be a successful waterproofing system for this project. Fast and cost-effective application, as well as a precise membrane thickness and product consumption were achieved.

One of the main experiences gained was the high speed of application without compromising quality issues like consistent membrane thickness as well as safe and convenient working conditions.

The use of the same spraying robot for the waterproofing membrane and the sprayed concrete proved successful.

BASF UGC proposed the use of the sprayable waterproofing membrane MASTERSEAL® 345 in a sandwich structure between the original cast concrete and a new inner lining based on fibre reinforced sprayed.

The inner lining of sprayed concrete had a thickness of 4cm and was applied as a separate operation after installation of the sprayable waterproofing membrane. The membrane was applied in the entire tunnel profile including the walls and the crown. For aesthetic reasons a float finish of the sprayed concrete surface was carried out and tiles were applied to the walls up to the lighting level