WestConnex Highway Tunnels in Australia Specify PENETRON ADMIX to Ensure Durability

The M4-M5 Link Tunnels, the latest construction stage of the massive WestConnex highway project for Sydney, Australia, were ceremoniously opened to traffic in January 2023. PENETRON ADMIX, a crystalline concrete waterproofing admixture, was specified to ensure the impermeability of the new WestConnex tunnels.

WestConnex is designed to improve connections between Sydney’s eastern and western districts, ease congestion, and link the city’s network of highways. The $16.8 billion project is the largest road infrastructure project ever undertaken in Australia. This stage of the highway network expansion encompasses 33 km (21 miles) of mostly underground highway.

The first of the tunnels, the M4 East, opened to traffic in July 2019. The second tunnel, the M8 Motorway, opened to traffic a year later in July 2020. The newly completed M4-M5 Link Tunnels consist of twin 7.5-km (4.65-mile) four-lane tunnels linking the new M4 tunnels with the M5 motorway and form a bypass of Sydney’s Central Business District.

During the planning phase of the WestConnex tunnels, the project engineers needed an optimal concrete admixture that would ensure impermeable and durable concrete tunnel walls for the most recent phase of construction. Penetron Australia provided test results that showed how PENETRON ADMIX-treated concrete provided enhanced corrosion resistance and substantially improved the durability of concrete, even under the high hydrostatic conditions of the subterranean tunnels of the WestConnex highway network.

“Thanks to Penetron’s success with tunnel projects around the world, PENETRON ADMIX was specified for the concrete mix used for the M4-M5 Link Tunnels,” explains Steve Hodkinson, General Manager of Penetron Australia.

Once added to the concrete mix during the batching phase, the active ingredients in PENETRON ADMIX create a non-soluble crystalline network, which forms throughout the micro-pores and capillary tracts of the concrete, dramatically decreasing concrete permeability.

“By adding PENETRON ADMIX to the mix, contractors can enhance the service life of the concrete, as it will be less likely to crack, spall, or deteriorate due to water and corrosion related damage,” says Steve Hodkinson. “The concrete matrix now also has the ability to self-heal and seal any micro-cracks that may occur in the future, drastically reducing the need for any future concrete waterproofing-related maintenance and repairs.”