Biochar from residual biomass as a concrete filler for improved thermal and acoustic properties

Highlights: • The addition of biochar at 15% by weight decreased the concrete density to 1454 kg/m³. • Biochar improved the sound absorption coefficient of concrete across the range of 200–2000 Hz. • The biochar decreases the temperature dependant thermal conductivity of the concrete, to a lowest value of 0.192 W/(m·K). • The concrete required more water to maintain workability, with 1 L of excess water being required per 1 kg of biochar. • Biochar addition at lower concentrations showed no detrimental effects to the compressive strengths of the concrete. -- Abstract: The current imbalance of carbon in the atmosphere is stimulating the search for carbon sequestration opportunities and for alternative processes and products with a reduced carbon footprint. Biochar, produced from residual biomass of the bio-ethanol industry (Dry Distillers Grains), was added as filler to a standard concrete, aiming at finding potential solutions for simultaneous carbon sequestration and improved properties and performance of the concrete. The addition of biochar resulted in a linear decrease in concrete density, with a concrete density of 1454 kg/m³ for 15 wt% biochar. The addition of biochar also considerably increased the sound absorption coefficient of concrete across the range of 200–2000 Hz, as it created pore networks within the concrete. The thermal conductivity of the concrete showed the largest reductions with 2 wt% of biochar, reaching lows of 0.192 W/(m·K). Finally, the incorporation of biochar showed a detrimental effect on the compressive strength of the concrete, which would put bio-enhanced concretes in the low-strength concrete classification category.