Wood wool cement board
Wood-wood slabs were originally made of long-fibre wood shavings compressed and bound together with cement. They are fire-resistant and have good insulating properties. At one stage they were used extensively as permanent formwork. However it has been found that the concrete around the slabs tends to be poorly compacted, leading to poor durability of any reinforcing steel in the area. Hence wood-wool slabs are currently little used in the UK for permanent formwork.
Wood-wool has become a generic term. Many product variations exist which use cement, lime or gypsum to bind wood shavings, wood chip or other wood fibres to form a composite board. Each type will have its own properties.