deconstruction concrete
Recarbonation of rubble With the objective of carbon neutrality set by the concrete sector, another interesting avenue is to be exploited: recarbonate the rubble . This process consists of leaving the rubble from the demolition in the open air, or by subjecting it to an accelerated treatment to recarbonate this cuttings. CO 2 is then reabsorbed in the rubble, which will harden and form better quality aggregates. This trapping phenomenon of the concrete is very important, because it makes it possible to balance the carbon balance of the concrete a little more, even if we do not necessarily achieve carbon neutrality. Moreover, this phenomenon also occurs when the concrete is in the form of a structure (building, work of art, etc.), but the reaction is less important, because it takes place on small surfaces where there is an interaction between air and concrete. However, when the concrete is demolished and in the form of rubble, the exchange surface with the air is all the greater and the recarbonation reaction accelerates.récupération de béton How does carbonation work? During the manufacture of concrete, the mixture of water and cement forms hydrates which will contribute to the resistance of concrete. When these hydrates are in contact with CO 2 from the air, an irreversible and slow carbonation reaction occurs. The CO 2 will penetrate the concrete Change of properties between recycled concrete and conventional concrete Aggregates and recycled sand modify the physico-chemical characteristics of concrete . Beyond an incorporation of 10% of recycled aggregates, there may be a reduction in the mechanical resistance to compression, the Young's modulus and the tensile strength by splitting. In addition, it can modify the drying kinetics and the gas permeability. The fresh concrete would thus be more manageable. Hardened concrete may undergo the formation of thaumasite (sulphate reactions) and swelling. On the other hand, there is practically no cracking and the adhesion of the concrete to the metal reinforcements is correct. As for frost resistance, this will depend on the original concrete of the recyclates, and for fire resistance, recycled concretes are more resistant, since they have lower internal temperatures.