We can control the ACT process to engineer the optimum end-product, currently a granular solid with many valuable applications, including aggregates for construction and agricultural fertiliser. We are working on a number of other high value products for the construction and chemicals industries.
We have been using ACT to manufacture aggregate since 1999, when we first applied it at pilot scale at the Astra Fireworks site. We observed that the clay-rich, contaminated soils at the site formed small pellets during treatment and that these pellets were resilient and survived the rigours of weathering in the wetting and drying environment of Astra’s test cells.
Aggregate can be manufactured using ACT from a wide range of residues, including red mud from aluminium processing, fines from washing soil or crushed rocks in quarries and ashes from a range of thermal processes.
The aggregate can then be used in a range of construction-based applications including general granular fill, road base, pipe bedding, general ready-mix concrete or for pre-cast concrete products. The aggregates are lightweight (< 1200 kg/m³) and either low carbon or carbon negative depending on the reactivity of the residue treated. ACT has worldwide potential and offers particular advantages in countries suffering from shortages of natural aggregates. In India, for example, treatment of the country’s substantial amounts of industrial waste has the potential to significantly reduce those shortages.
Typical properties of the aggregate can be found here.