Biochar as the rheological modifier in three-dimensional printed concrete

Biochar is recognized as a carbon-negative material in recent years, which has emerged as a prospective option for substituting Portland cement or even replacing aggregate for many construction materials. Biochar has the potential to enhance the mechanical properties of concrete and reduce cement usage, thereby mitigating CO2 emissions associated with concrete manufacturing. As a result, biochar has a great potential to become a focal point in the field construction. Furthermore, the researches focusing on biochar enhanced three-dimensional printed concrete (3DPC) are of significant importance to realize the sustainable development of the cement concrete and ensure the green construction of engineering structures towards carbon neutrality. This chapter overviewed the research progress of biochar as the rheological modifier in 3DPC from the aspects of biochar basic properties, rheology of 3DPC, fresh-state behaviour of biochar–cement composites, and materials microstructure, fresh-state behaviour, early-age performance and benefits of biochar as a rheological modifier for 3DPC.