Onuaguluchi, et al (2024) Sludge-derived biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More as an additive in cement mortar: Mechanical strength and life cycle assessment (LCA). Construction and Building Materials. https://doi.org/10.1016/j.conbuildmat.2024.135959

In a recent study, researchers explored an innovative approach to managing sewage sludge (SS) from wastewater treatment plants by transforming it into biochar (BC) and utilizing it as an additive in cement mortar mixtures. The study aimed to provide an alternative, environmentally friendly solution to the disposal of SS, which poses significant environmental contamination risks. By pyrolyzing SS in either nitrogen (N2) or carbon dioxide (CO2) environments, the researchers generated BC powders, which were then incorporated into cement mortar at varying weights.

The investigation revealed that adding a small dose (0.5-2 wt%) of BC to cement mortar significantly enhanced its mechanical strength properties without adversely affecting its fresh properties. The compressive and tensile strengths of the BC-modified mortar were notably higher compared to plain mortar. Specifically, BC produced under a CO2 atmosphere proved more effective than its N2 counterpart, particularly when pre-wetted, leading to superior mechanical strength outcomes.

Furthermore, a life cycle assessment (LCA) demonstrated that, except for minimal increases in particulate matter and water consumption potential, BC addition generally decreased the environmental impact categories associated with cement mortar production. Notably, the Global Warming Potential (GWP) of the BC-modified mortar was lower than that of plain mortar, indicating a reduction in the environmental footprint.

This study suggests that using SS-derived BC as a low-dose additive in cement composites could significantly benefit the construction industry by enhancing material properties while mitigating environmental impacts. The findings highlight the potential for such innovative reuse strategies to address the challenges of SS disposal and contribute to more sustainable construction practices.