Asphalt Specialists In Hydraulic Engineering


Coastal Protection
Dam Waterproofing
Dam Erosion Protection
Dam Spillway Protection
Ports & Harbours
Flood Alleviation
River Training
Scour Protection

Underwater Impact Protection

Strengthening Rock Structures
Landfill Linings
Offshore Services

underwaterUnderwater Structures

The use of asphalt underwater has been developed for scour protection but there are many other applications.

Typical applications

  • Protection of tunnels, for example, under a busy port waterway
  • Protection of pipelines and cables under canals from dredging work or anchor drag
  • Outfall structures
  • Protection of sluice aprons

A choice of materials

  • A grouted stone layer
  • Prefabricated mattresses of Open Stone Asphalt
  • Prefabricated mattresses of Dense Stone Asphalt

The mastic / rock combination

A superior alternative to rock alone:

  • Reduces the amount of rock
  • Increases the security of the structure
  • Mastic’s thermoplastic properties give excellent performance under short-term high impact loads as well as under long-term settlement load

Tunnel Roof Protection

OSA Mattress
Tunnel Roof Protection

Where tunnels pass beneath navigable waterways there is a risk of damage to the tunnel structure from anchor drops.

Traditionally the tunnel has been positioned deeper to keep away from the anchors, or a relatively thick layer of rock armour has been used.  Reinforced concrete is an option but it is not flexible to withstand settlements/riverbed movements. Concrete is not an ideal material to withstand high impact loads.

Asphalt mattresses are another option which can give the following advantages :

  • Relatively thin mattresses – typically 0.25-0.30m thick.
  • Flexible material to withstand settlements at edges.
  • Excellent properties against high impact loads.

The thinner construction may give the following advantages :

  • Shallower excavation required for tunnel construction, therefore easier.
  • Less excavation required, therefore quicker.
  • Possible savings on approach works to the tunnel – also less deep constructions.