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Use of fly ash as fill under a concrete slab

Fly ash is a by-product of coal combustion in power stations and can enhance the strength, workability and durability of concrete. Read more.
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Concrete-grade fly ash is commonly used as a 20–30% cement replacement in concrete. Why? Because it provides greater strength, workability and durability to concrete.

A by-product of coal combustion, fly ash can be a very useful supplementary cementitious material. However, if may not always be appropriate as a filling or a base to site slab panels or slab beams on.

This resource outlines the requirements of the National Construction Code (NCC) Volume Two and AS 2870 – Residential slabs and footings for the type of material that can be used as fill, compaction of fill under concrete slabs and bearing strength.

It shows that when a concrete slab has been designed using Deemed-to-Satisfy construction provisions or according to the requirements of AS 2870, fly ash can not be considered a suitable fill or base. But it can be used in other suitable circumstances.

Find out more about the requirements for fill under concrete slabs and what measures must be taken to ensure suitable bearing capacity for building loads. It’s essential information for any residential building professional.

Access this resource now

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Who is it for?

Residential builders and industry professionals

This resource is designed for builders and industry professionals who want to understand how to improve the performance and quality of concrete using fly ash.

What does it include?

  • Requirements for fill under concrete slabs
  • Durability properties of concrete
  • National Construction Code (NCC) Volume Two
  • Requirements for AS 2870 – Residential slabs and footings

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