Projet BIOGRAFIC – Valorisation des cendres BIOmasse en tant que GRAnulats et FIller dans les blocs de Construction

Project description

Biomass installations today produce more than 200,000 tonnes of ash in France. This ash represents a significant quantity of waste that operators of biomass power plants must recover or eliminate, depending on the type of ash (sub-hearth, fly ash), the combustion technology used (grate boilers, fluidized bed, spreader store ) and existing treatment channels (agronomic recovery, sending to landfill, etc.).

An interesting way of recovering wood boiler ashes concerns their use in building materials. Each year in France, more than 117 million tons of aggregates are used, the vast majority of which come from the extraction of quarries or rivers. However, these resources are becoming scarcer and more and more difficult to access. The construction sector has developed materials by replacing some of the traditional raw materials (cement, aggregates) with secondary raw materials (blast furnace slag, fly ash, recycled aggregates, etc.).

The objective of the BIOGRAFIC project is to assess the potential for recovering ash from fluidized bed biomass boilers as a substitute for natural aggregates in dry concrete with immediate release for the manufacture of masonry blocks for construction. The substitution of sand and gravel will make it possible to recover a large volume of ashes. A territorial and economic study made it possible to estimate at approximately 12.6 kt and 37.7 kt respectively for the low hypothesis and the high hypothesis the biomass ash deposits available in the Hauts-de-France region and at 5.0 kt and 15.7 kt respectively for the low hypothesis and the high hypothesis for the Breton territory. This figure is bound to increase due to the growing development of this type of boiler room. The introduction of a by-product from biomass into a cementitious matrix must however be the subject of a preliminary study given the complexity of the interaction of the ashes with the mixing water and the various constituents of the concrete. The health and environmental performance of masonry blocks incorporating biomass ash will also need to be assessed.

The laboratory stage is essential before considering a transition to an industrial scale and demonstrating the feasibility of the characteristics of the final product to be marketed. An industrial test phase, i.e. the large-scale manufacture of mixtures validated in the laboratory, is planned. The manufactured blocks will be sent to CERIB for additional tests which could lead to the certification of the product with a view to marketing.

Scientific contributions from the laboratory

The Civil Engineering and Geo-Environment Laboratory (LGCgE – IUT Béthune, ER3 Team) of the University of Artois will bring to the project its skills in the formulation and characterization of eco-materials for civil engineering.