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Portfolio: TTC Subway Tunnel Expansion Joints Repaired


Toronto, ON

Repair Types:

Joint injection

This project consisted of waterproofing tunnel rigs through injection of PolyFlex into joints. Due to extremely high static hydraulic pressure, the application presents its own challenges. 

The process of injection of PolyFlex fills all the cavities of the expansion joints as well as voids around the tunnel. PolyFlex does not react with water, which makes it ideal for waterproofing applications with actively running or standing water. Upon injection, PolyFlex will displace and remove the water from all possible voids. This provides a long lasting waterproofing solution. 

Concrete Patching Work


 Repairs were done on the ceiling of the tunnel with use of Polyforce Plus and Basalt mix. This mix is made to be a paste like consistency, which allows the patching work to be done without forming. The ceiling of the tunnel has a rounded shape, which makes the form installation next to impossible. 

The Polyforce Plus and Basalt mix is flexible in its natural state and will expand and contract with concrete. The adhesive strength of Polyforce Plus is 1.5 times stronger than the concrete itself, which ensures a long lasting result with monolithic bond. 


Facts In accordance with third-party testing, the repaired surfaces are rated to the following: 

Polyforce Plus

  • 25 years of useful life

  • 0% water permeation 

  • Polyforce Plus is rated to expand and contract with concrete 

  • The entire surface and volume of the slab is "monolithic" Polyforce Plus compressive strength of 85 MPa 

  • Basalt mix compressive strength of 150 MPa 

  • Adhesive strength of 1.85 MPa (original concrete has only 1.2 MPa of a tensile strength, so the bond is stronger than the concrete itself) 

  • Repair is 60% cost of a traditional repair

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