Backfill materials

  • Bentonite pellets enable water to slowly encounter the clay, as the water is absorbed by the pellets and the clay expands to fill cavities between the pellets and the surrounding soil. Once fully expanded, the clay forms an impermeable barrier, which is why the pellets are perfect for sealing water and geothermal boreholes.
  • Bentonite powder is mixed with water before being pumped into a hole. Like bentonite pellets, this then mixes together and expands down the hole, creating a seal.
  • Bentonite granules are used on sites for dry borehole backfilling, mostly on landfill sites and for underground engineering applications.
  • Bentonite cement grout mix has a ratio of two parts bentonite and one part cement. It is used for backfilling boreholes as the cement present within the bentonite creates a stronger seal. A stronger seal may be needed for inclinometer casing or if piezo vibration is present while installing.
  • Bentonite cement pellets are like bentonite pellets but with cement present within them. This is the same ratio as our grout mix but in pellet form. These create a stronger sealing clay.
  • 10-mm pea gravel can be used to backfill holes or it can be mixed with post mix or cement to create a solid concrete.
  • Post mix (20 kg) and cement (25 kg) can be mixed with filter sand or pea gravel to create the ideal mix for securing metal covers at the top of the borehole.
  • Quartz filter sand is a high-specification filter pack that is heat dried and filtered with a very close tolerance. Available in 25-kg bags and as 1–2 mm to 2–4 mm or 3–6 mm to 6–10 mm.

Filter materials are used in boreholes where there is a need to have a filter in place for a substance, usually water, to be filtered through before entering the plastic installation pipe. Quarried silica sand is offered in different grades and has been washed, dried and filtered to the size required. All the products are stocked in 25 kg bags.