Prefabrication of structural walls from large mineral rubble

Abstract

Abstract This paper presents a new, low-carbon prefabrication process for load-bearing structural walls. It reuses large flat concrete and stone rubble sourced from demolition waste, is readily scalable, and operates under controlled factory conditions, combining the structural logic of masonry with industrialized concrete prefabrication methods. The process begins by sourcing the mineral rubble pieces from demolition sites or recycling centers. Each piece is digitally inventoried by processing pictures taken on the worksite. The pieces are then virtually selected and arranged to determine their best assembly geometry, maximizing load-bearing capacity while minimizing void volume. Next, the pieces are placed horizontally on a tilting table according to the generated layout. A low-impact recycled concrete is poured into the voids. Once the material has hardened, the wall is tilted and lifted in its vertical orientation. Four full-scale walls have been built to assess technical feasibility, environmental performance, and structural behavior, and to provide relevant insights into productivity and potential process improvements. Preliminary compression testing demonstrates sufficient resistance for structural walls in low- to mid-rise buildings under conventional loads. Prototypical fabrication highlighted lower fabrication speed and higher labor demand than for traditional precast concrete walls, while optimistic estimates of batch processing suggest similar fabrication rates. A Life Cycle Assessment shows reductions of up to 83% in CO 2 eq emissions compared with recycled concrete walls, while significantly increasing the circularity of concrete.