New circular, sustainable building composite material made of building wastes

Horvath, Mélanie [UCL] Bollen, Pierre [UCL] Trachte, Sophie [ULiège] Pardoen, Thomas [UCL]

A novel class of circular, sustainable composites for building applications has been developed in the context of the CO2 emission and waste production impact of the construction sector on environment. The material is made of two secondary raw materials, fibres and sand, from waste recycling channels while the binder is hydraulic lime, the only feedstock entering the composition. The material exhibits unexpectedly high ductility with significant strain hardening capacity whose origin is unravelled using microCT. Aside from a very low embodied energy, the composite offers also a remarkable combination of thermal and acoustic insulation, sufficient stiffness and strength for several building applications. This makes the material competitive with aerated concrete and lime-hemp blocks. Furthermore, the manufacturing does not involve any baking cycle and its implementation meets circular building requirements thanks to reversible and reusable assembly systems for applications as blocks, wall and floor panels. Re-recycled products maintain the good performances.