Effect of binders on 3D-printed concrete containing bio-based aggregates

Reducing CO 2 emissions is a critical priority in the construction industry. This study investigates CO 2 storage in 3D-printed hempcrete while achieving sufficient mechanical properties for envelope or shell element applications. The use of hemp shives as bio-based aggregates with cement, hydrated lime, and hydraulic lime-based binders was investigated to develop low carbon 3D-printable hempcrete. The mixtures were evaluated for printability, fresh-state properties, mechanical performance, thermal conductivity, and CO 2 emissions. Hydrated lime mixtures exhibited lower compressive strength than cement and hydraulic lime-based mixtures after 7, 28, and 90 days of curing. Hemp shives reduced compressive strength by up to 80.1% compared with the corresponding cement mortar. Hydraulic lime-based hempcrete showed the lowest CO 2 emissions, reaching 15.15 kg CO 2 -eq/MPa of compressive strength. These results demonstrate the potential of hydraulic lime-based binders for extrusion-based 3D printing of sustainable hempcrete envelope or shell elements.