Keppel MRT Station & Circle Line 6 Tunnel, Singapore

The CCL 6 C882 project completes the final segment of the Circle Line, connecting HarbourFront MRT Station to Marina Bay MRT Station via twin tunnels leading to Keppel Station. As part of the works, two cross passages were constructed between the twin tunnels—one measuring 43.5 m long with two sump pits, and the other 27.1 m long.

To accelerate cross passage construction and prevent knock on delays to adjacent activities, Sika partnered with an experienced specialist applicator to propose a compatible spray waterproofing membrane installed between the sprayed concrete primary lining and the cast in situ secondary lining. The installation methodology was carefully developed to comply with Land Transport Authority (LTA) requirements while optimising construction efficiency and minimising installation time.

Mining and primary lining were first completed to the mid tunnel from one side, followed by the application of waterproofing and installation of the secondary lining, before the same sequence was executed from the opposite side to complete the tunnel.

Waterproofing was achieved using Sikalastic®-245, sprayed between the sprayed concrete primary lining and the cast in situ secondary lining in three stages—overhead, axis level, and invert level. 

Sikalastic®-245’s double bonded performance to both primary and secondary linings prevent lateral water migration, while its fast curing and quick wetting polymer allow rapid secondary lining installation with excellent film continuity. In addition, Sikalastic®-245 offers high elasticity and contains no toxic components, supporting both performance and site safety.

Sikalastic®-245 — Spray Applied Waterproofing Membrane