Underground pipe insulation and protection fill


When laying underground pipes and ducts, the use of Laterlite Expanded Clay (or the hydrophobic Laterlite Plus version) as an insulation and protection fill material for the trench backfill around the pipe has many advantages:

  • Easy and safe to lay. The granularity and lightness of these products make them easy to lay, requiring little or no compaction. The clay granules close the voids around the pipe by simple gravity, minimising the risk of damaging it, as can typically occur when backfilling or compacting with traditional aggregates.
  • Reduced risk and simplified maintenance. When re-excavation is required at a later date, the expanded clay makes it easy to locate the position of the pipe, reducing the risk of accidental breakage. Because the expanded clay is lightweight and loose it is easy to remove and simplifies the inspection process.
  • Thermal insulation and front protection. The layer of expanded clay insulates the pipework, reducing thermal dispersion and minimising the risk of freezing if water pipes have been buried close to the surface or have been laid to fall with a very shallow angle of slope.
  • Protection from vibration and settlement. Additional loading on buried pipelines caused by ground settlement, vibration, seismic movement, or landslip is not transferred to the pipe itself. This is a particularly significant advantage if the pipe carries flammable or toxic liquids or gases and is under pressure.
  • Draining capacity. By preventing water from stagnating close to pipe, the draining capacity of expanded clay safeguards its long-term durability. The Laterlite Plus hydrophobic variant ensures that the level of humidity in the immediate vicinity of the pipe will be extremely low.


For these applications, Laterlite Expanded Clay is usually laid loose, although to meet specific strength or cohesion requirements it can be bound with cement to create a pervious draining concrete

See also the geotechnical section of the site and the page dedicated to the insulation of tanks and ducts



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