GREEN CAST is a foamed material made exclusively of alkali activated fly ash, without Portland cement at all. It has been thought to be a green alternative to AAC for non-structural applications. This initiative aims at helping the environment by reducing the amount of fly ash that is landfilled and at the same time promoting a competitive material for the building industry.


GREEN CAST is made of fly ash obtained as by-product in thermal power plants, therefore its carbon footprint is considered null. The GREEN CAST material is manufactured in a low energy consuming process.



Due to its high porosity GREEN CAST offers superior thermal and acoustic insulation performance compared to conventional AAC maintaining low density and good mechanical resistance.

ð (kg/m3)MF (MPa)MC (MPa)λ (W/mK)Ra
GREEN CAST660-7800.54.80.1436

Two pilots were built with GREEN CAST and conventional AAC respectively (16 m3), and their thermal inertia was compared over a period of 33 days in a summer regime in Madrid. In order to keep both pilots at the same temperature,GREEN CAST building required less energy.

Costs analysis

A production plant has been ideated by converting a conventional AAC plant into a GREEN CAST production plant, considering raw materials, personnel, production costs, investment, 10 years depreciation and a yearly production of 50,000 m3.

According to a preliminary business model GREEN CAST should cost around 90€/m3 against 100€/m3 of conventional AAC. Please note that all operative costs are related to Western European Countries.