Cement and Concrete
The use of CCPs in the manufacture of cement and concrete products represents the largest sector for utilisation. Emerging opportunities for producing artificial aggregates for use in concrete are increasing, due to the continued depletion of natural aggregate resources.
As FA is a source of silica and alumina, it can be used in the manufacture of Portland cement, in two key ways:
- As a raw material in the manufacturing process of clinker to provide silica, alumina and other minerals.
- As a supplementary cementitious material blended with Portland cement to produce products termed blended cements.
The use of fly ash as a partial cement replacement in typical concrete serves a range of purposes. In many Australian states, FA concretes form the benchmark for ‘Normal Class Concrete’ types described in Australian Standards AS3600 and AS1379 and supplied to most major projects. FA use adds many benefits to concrete that facilitate improved design and construction solutions on projects.
The specific benefits of including FA in concrete include enhancing:
- Early age plastic and hardening concrete properties,
- Concrete mechanical properties at ages - 28 days to 56 days and
- The long-term properties of concrete for ages in excess of 56 days
Further opportunities exist for increasing the use of FA in concrete, with a better understanding of the material and how it affects the concrete within which it is included. FA can often reduce the cost of a concrete mix that is designed to meet specific criteria. In addition, environmental benefits can also be achieved with the appropriate inclusion of FA in concrete.
Importantly, the ADAA advocates the inclusion of FA in concrete where appropriate design; construction, sustainability and other project factors are considered - taking into account relevant technical based information.
For further details on the Australian experience with FA in concrete click here.