Carbon-negative concrete by using biochar

In this paper we present the realization of carbon negative concrete by substituting cement and aggregate with biochar. By conveniently choosing feedstock and properties of biochar, it is possible to maintain the same compression strength of standard concrete. Several biochar types derived from different vegetal feedstocks were used, that were characterized for their composition and physical properties. The effect of biochar type and grain size distribution was studied, demonstrating the possibility of maintaining or even slightly improving the mechanical properties of mortar and concrete, depending on the biochar content. The physical properties and pore distribution of mortar containing biochar was also studied in detail in order to understand the reason behind the mechanical properties improvement observed at low biochar content.