clinkaFILL – Expanded Clay Aggregate

clinkaFILL is lightweight clay aggregate

The small clinka balls have thousands of tiny air cells with a hard shell of baked clay.

clinkaFILL has many applications where its lightweight and high strength make it a premium choice:

  • insulating fill under concrete slabs
  • green roof drainage and soil media layers;
  • aggregate in lightweight concrete and masonry;
  • freedraining fill behind retaining walls and around trafficable tunnels;
  • bulk fill for settlement prevention for roads and embankments built on soft ground


The ‘coated’ version of clinkaFILL is used as bulk fill under concrete slabs (generally as a layer 150mm thick) to create a completely insulated building envelope (especially useful to maximise efficiency when in-slab hydronic heating is specified – but also to satisfy new BCA energy efficiency requirements).   It adds an additional insulation of R1.77 to the underside of the slab. clinkaFILL does not require compacting when placed at 150mm thick – and due to its high void structure and coating – it will act as a vapour barrier, removing the need for polythene sheeting under slabs (subject to building surveyor approval). Coating is done with a very mild soft brown soap.

clinkaFILL is an excellent backfilling material against retaining walls where its high void content is free draining (to reduce hydraulic loadings); lightweight (to reduce horizontal stresses); non-compressible once placed; and is also highly durable insulation. clinkaFILL is light enough to be easily placed manually – if machines cannot access the fill location or if the use of a machine would be cost-prohibitive for short periods.

clinkaFILL is made from ‘fat’ clay that is passed through a rotary kiln where the clay expands to small balls. During the burning all excess organic material is lost.