Owing to the inherent complexity of construction, tunnels must have a life expectancy of several decades.

All components of these works should have similar characteristics, especially the waterproofing system. The waterproof liner protects and makes the construction safer. Over its whole working life, it allows considerable cost savings in terms of maintenance and repair. Since the creation of the first tunnels, water seepage has been one of the main problems. Virtually no tunnel is ever bored into a completely dry substrate.

Historically, water has been one of the most serious problems encountered in underground works
and it requires extremely expensive repair and renovation works.

The essential characteristics of a waterproofing liner for tunnel works are a high physical-chemical performance with minimum maintenance during its lifespan.

This means optimisation of results from every perspective: mechanical resistance, resistance to ageing, flexibility, ease of installation and – last but not least – environmental protection.

The main characteristics of liners for tunnel works are:


Excellent weldability

Softness and flexibility

High ultimate elongation
(dimensional variation of the membrane when subjected to mechanical stress)

Tensile strength (the membrane can resist tensile stress without tearing)


Adaptability to irregular substrates

Maintains its integrity even in the case of structural movements or soil subsidence

High electrical resistance

Suitable for installation in humid places

Resistance to static puncturing

Resistance to dynamic puncturing

Chemical resistance

Resistance to bacteria and fungi

Resistance to micro-organisms

Resistance to roots

Fire resistance

Compatibility with drinking water

Signal layer surface (essential feature to check the liner once installed. Any surface damage of the liner is immediately shown by the different colour appearing from the surface underneath)

Another basic aspect is ease of application, where the sealing of the waterproofing membrane should allow for the execution of complex details and particulars, especially in difficult situations on site.

This is essential for the successful result of the overall system.

The following characteristics should be considered:

Easy weldabiltity and workability of the material

Compatibility with special accessories

Ease of performing quality tests in the post-application stage (specifically, checking the welded seams)

Selecting the correct waterproofing membrane with the required mechanical characteristics is essential to the success and durability of the project.

The membrane must be able to adapt to the extreme conditions that may be encountered in this type of project.

All synthetic liners for tunnel works (PVC or TPO) are formulated and manufactured to meet these specific requirements.

They can be selected according to their mechanical and performance characteristics, as regards: ultimate elongation, tensile strength, resistance to static and dynamic puncturing, chemical and biological resistance, fire resistance, compatibility with drinking water.

The synthetic liners can be used in all type of tunnelling works:

NATURAL TUNNELS (with or without water under pressure)




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