The cultivation of algae necessary for the creation of a zero-emission concrete, through biogenic limestone

The world of cement and concrete has been in turmoil for some time to create new carbon free mixtures, which do not affect the natural resources normally taken from the quarries.

Recipes were experimented with a percentage of construction waste from the recycling of materials from renovations and demolitions, mixtures with variable percentages of non-recyclable plastic waste and mixtures with waste from waste incinerators and steel mills.

All recipes are aimed at better waste management in the circular economy, which promotes every action aimed at recycling the waste we produce, reducing the collection of natural raw materials and the reduction of non-recyclable waste.

Another chapter of sustainability has been opened, for now in an experimental way, by the University of Colorado, which is studying the possibility of using algae for production of biogenetic limestone for the production of bio cement, mortars and concretes.

The University has created a cultivation of Coccolithophores, single-celled algae belonging to the Aptophyte family, which have the characteristic of being covered with calcium carbonate flakes. The presence of this element in algae may be the key to its use in replacing the natural element in cement mixtures.

In fact the limestone that, by means of photosynthesis, the algae naturally produce, can be compatible with the natural one, giving life to a component of the dough not only with emissions zero, but even negative, as the coccolithophores absorb CO2 during their life.

In fact, we can speak of concrete or carbon neutral cement because the carbon dioxide released into the atmosphere, when burned to produce cement, is the same as that which microalgae extracted from the atmosphere during its growth.

Instead we can speak of cement or concrete carbon negative, if the natural limestone used in the mixtures is completely replaced by that coming from algae, in fact, during their life have absorbed CO2 into the environment and it is not necessary to emit more for its production.

According to the University scholars, the large-scale adoption of this theory would save the planet about two gigatonnes of CO2 emitted per year and the sequestration of 250 million tons.

American researchers estimate that with 500,000 or 1,000,000 hectares of open ponds in the United States, the country could make enough calcium carbonate to make all the cement it needs.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.