Potential of biochar use in building materials

A critical review of the articles dealing with biochar in terms of the reuse of biomass waste in building materials and its impact on material properties was conducted using five different electronic databases; thirteen articles were selected for this critical review. Biochar was used as a replacement for cement and aggregate in cementitious composites and as an addition in wood polypropylene composites and plasters. The biochar dosages ranged from 0.5% to 40%; in most composites, the addition of biochar increased strength and reduced thermal conductivity and the bulk density of fresh mortars. Also, biochar dosages of 0.5–2% decreased, while dosages of 10–40% increased water absorption and penetration on cementitious composites. The selected studies mainly introduced biochar use in building materials as a means of biomass waste reduction and its reuse for various purposes, while carbon footprint reduction was addressed in only a few of them. Biochar-containing building material's capability of capturing CO2 from the air was also observed (0.033 mmol CO2 gbiochar−1 to 0.138 mmol CO2 gbiochar−1). The results also showed that mortars with CO2-unsaturated biochar had better mechanical and physical properties than mortars with CO2-saturated biochar. Selected studies showed biochar-containing building materials have a great potential for carbon footprint reduction. However, there is a lack of comprehensive studies about biochar use in building materials concerning climate change mitigation. •Material recovery of waste biomass after pyrolysis in the form of biochar.•The first systematic literature search on biochar-containing building materials.•The addition of biochar improved mechanical, physical, and chemical properties.•Significant carbon footprint reduction potential of biochar in building materials.