Concrete is the main building material in construction worldwide and the material demands are going to
rise even further in the future. This is due to its free formability, its compressive strength as well as its
excellent durability. The most used binder in concrete is cement which produces high amounts of CO 2 in
its production. Thus, research and the building industry must strive towards more environmental-friendly
concretes. This work proposes the use of biochar from residual biomass as aggregates in a cement
reduced UHPC-system to gain a CO 2 -reduced concrete with sufficient mechanical properties. The results
have shown that the biochar aggregates have a significant impact on the compressive strength of the
concrete. Future investigations will focus on the use biochars derived from different feedstocks as well as
on the use of bio-waste ashes as alternative binders in concretes to reduce the CO 2 -footprint even more.
Furthermore, the mixing process of the material has to be optimized due to the low density of the biochars.