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With tunnel construction underway or literally 'in the pipeline' all around Australia, Fosroc ANZ can now offer engineers more choice in tunnel waterproofing solutions. Our new PVC, loose laid membrane Proofex PGP is the leading product in a full waterproofing system for tunnels built with the New Austrian Tunnelling Method (NATM), which is often used in cities where existing infrastructure makes 'cut and cover' construction impossible.

The addition of Proofex PGP to our range means we can support our customers with the most common below ground construction methods. As well as tunnels, Proofex PGP is also recommended for waterproofing basements and lift pits, buried or paved roofs, and planters.

Colin Picton, Fosroc ANZ's Product Segment Specialist for Waterproofing & Sealants, explains the choice:

"Proofex Engage and Proofex 3100 are leading products for waterproofing cut and cover tunnels. Now we have Proofex PGP, which is ideal for NATM tunnels," Colin says. "Globally, PVC membranes are already well entrenched and Fosroc is highly experienced in working on headline projects, including London’s Crossrail (now known as the Elizabeth Line) and the Riyadh Metro, with both leveraged the NATM or sequential excavation."

Fast, flexible and puncture resistant

While Proofex PGP can be applied as a fully bonded membrane, its ability to be loose laid in 25-metre rolls adds huge value when construction schedules are tight. It is both flexible and fast to install. Hot air welding the membrane joints ensures maximum watertightness. For vertical applications such as tunnels, Proofex PGP Fitters provide a weldable fixing detail.

These are Proofex PGP's key benefits for waterproofing specifiers:

  • Easy to install – high flexibility even in cold temperatures.
  • High puncture resistance.
  • Quality control during application – the membrane is coloured light grey on top and black on the underside, making any tears easy to spot.
  • Root resistant to CEN/TS 14416.
  • Hot air welded joints ensure excellent watertightness.

New Austrian Tunnelling Method: a complete Fosroc waterproofing system

With Proofex PGP, Fosroc ANZ can now supply a full NATM tunnel waterproofing system.

In NATM constructions, the tunnel is sequentially excavated with boring machines, with the surrounding rock mass conserved as the main component of tunnel support.

This is how Fosroc ANZ products are used during NATM constructions:

  1. A thin layer of shotcrete is sprayed on immediately after face advance.
  2. Nitofill LV is injected into any cracks in the shotcrete.
  3.  A high-density polyethylene (HDPE) drainage membrane, Proofex Sheetdrain 81 is applied next to the shotcrete and over drainage infrastructure.
  4. Proofex PGP PVC waterproofing membrane is then installed in 25-metre rolls, using hot air welding to seal the overlaps.
  5. Compartments can be laid out using Supercast PVC waterstops, which are welded to the membrane to restrict lateral water movement.
  6. The concrete tunnel lining is cast, providing the final structural support.
  7. Fosroc offers a range of waterstops to seal the concrete joints, including Supercast PVC, Hydrotite and Leakmaster. Supercast Predimax injection hose waterstops can also be installed to enable sealing of any future joint leaks.

"We have a full suite of products and expertise to ensure tunnel construction runs smoothly. Supercast PVC waterstops provide us with the ability to compartmentalise the waterproofing, restricting the lateral migration of water. Supercast Predimax is another excellent tool, allowing us to inject resin directly into the concrete construction joints and sealing voids," Colin explains.

Find out more

Are you involved in tunnel or basement construction in Australia and New Zealand?

  • Download our Tunnel Construction Solutions brochure.
  • Contact your Forsoc ANZ account manager or use the Get in Touch form at the bottom of this page. We will be in touch to discuss a full waterproofing solution.