Ingredients with bio content: they include rice husks (top left), ash from cassava peels (bottom left), karroo gum (centre) and coconut fibres (right).
Source: BAM, Image: Michael Danner
Precious plant remains: Wolfram Schmidt uses the shells of karroo acacia for his experiments. Strictly speaking, its juice.
He adds a lot of plant ingredients to the mix in the laboratory; they are supposed to replace the current chemical and mineral concrete additives.
Concrete made from cement, sand, limestone flour as well as plasticisers and binders is mixed in a liquidiser, from which a flat sample is cast...
... that is then tested using heavy machinery. Such a flat sample can contain sisal or coconut fibre reinforcement.