New Value, Less Waste: Sewage Sludge Biochar into Concrete
Presented By: Garrett Benisch
Affiliation: Bioforcetech
Description: Biochar produced from municipal wastewater solids known as biosolids exhibits unique properties that allow it to formulate into concrete as a partial aggregate replacement in significant quantities. As a contaminated material currently causing environmental harm and managed at a great cost, producing biochar from biosolids for use in the concrete sector has numerous benefits. This presentation will outline the full life cycle of a biosolids to biochar to concrete value chain and the benefits associated with it as compared to business as usual. This will be described through three steps: divert (from business as usual management), transform (into biochar), and apply (to concrete).
Efficacy of Biochar in Concrete for Carbon Storage
Presented By: Seth Kane
Affiliation: University of California Davis
Description: Current Intergovernmental Panel on Climate Change projections suggest that, alongside decarbonization, society must adopt carbon dioxide removal (CDR) strategies to mitigate climate impacts. Biochar is currently the most widely sold CDR mechanism; however, finding sustainable markets for biochar after carbon credits are sold remains a significant challenge for the industry. Given that concrete is the most widely used engineered material, integrating biochar into concrete as a carbon storage mechanism has been proposed as a promising avenue. However, not all biochars are equal in their performance in concrete, and variability in biochar feedstock properties and processing results in uncertainty in concrete strength, durability, and potential for CDR. This study examines biochar from various biomass sources, processing conditions, transportation distances, and replacement levels to assess its potential for reducing concrete's net emissions and serving as a storage mechanism while maintaining concrete strength. Our results indicate that maximizing the climate benefits of biochar in concrete may require efficient, industrial-scale slow pyrolysis systems and short transportation distances to batching facilities. We present scenarios where emissions reduction and carbon storage are achievable and identify areas for further research, such as the durability of biochar-concrete composites, to inform industry adoption of biochar as a method to sequester carbon in the built environment.
Biochar as a Sustainable Additive in Concrete with Natural and Recycled Aggregates
Presented By: Jiong Hu
Affiliation: University of Nebraska-Lincoln
Description: Biochar is a high-carbon solid material created through the thermal decomposition of organic biomass in a low or zero-oxygen environment. Its production and use offer substantial carbon sequestration potential, while its incorporation into concrete can significantly reduce the material's overall carbon footprint. This study examines the feasibility of using biochar as a beneficial additive in concrete. Beyond its environmental advantages, biochar's high surface area and absorption rate contribute to nucleation and densification effects, which can enhance both the mechanical strength and durability of concrete. The research involved a comprehensive evaluation of biochar derived from various sources, including distillers' grains, corn stover, wood waste, and red cedar, across different particle sizes and applied at various addition rates and cement replacement levels. Findings indicate that biochar can help offset the mechanical properties in concrete mixtures with reduced cement content. Additionally, biochar was applied as a coating on recycled concrete aggregates, enhancing the interfacial transition zone within the concrete and subsequently improving its performance. Preliminary economic and carbon footprint analyses support the feasibility and benefits of biochar's inclusion in concrete. Given the vast scale of potential concrete applications, the success of this project could substantially expand biochar's marketability and usage. Integrating biochar into concrete not only promotes carbon sequestration and storage markets/credits but also supports a safer, more sustainable infrastructure system, including pavement applications.
Hydration and Strength Development of Biochar Cement Composites
Presented By: Julia Hylton
Affiliation: Colorado School of Mines
Description: While many innovative solutions are emerging to address concrete’s carbon footprint, very few can result in a truly net zero concrete. In contrast, incorporating biochar as a partial cement replacement can result in a carbon-negative mortar with similar or improved strength compared to a control. Since not all biochar performs equally well, to ensure reliable performance in concrete it is necessary to understand and control the mechanisms for strength improvement in biochar cement composites. This talk will discuss how biochar contributes to strength improvements via the filler effect, internal curing, hydration/pozzolanic reactions, and carbonate formation.
How Concrete is Becoming a Carbon Sponge
Presented By: Mohamed Mahgoub
Affiliation: New Jersey Institute of Technology
Description: As concrete is the most widely produced material on Earth, finding ways to reduce its carbon footprint could have a significant impact on global emissions. With global carbon dioxide levels exceeding critical thresholds, the need for innovative approaches to reduce atmospheric carbon has never been more urgent. Our team was able to develop a concrete mixture that could sequester carbon. This research investigates the use of carbon-rich byproducts from organic waste—as an additive in concrete to simultaneously enhance its properties and sequester carbon. This study examines the effects of various dosages of additives on concrete’s workability, compressive strength, and air content. This research addresses a critical gap by evaluating the dual role of enhancing concrete and sequestering carbon, contributing to sustainable construction practices and global climate change mitigation efforts.
Route to Biochar Integration in Concrete: Addressing Workability, Strength, and Admixture Compatibility Challenges
Presented By: Jose Paul
Affiliation: CEMEX
Description: Biochar, derived from the pyrolysis of biomass in an oxygen deprived environment, is promising for carbon sequestration, thus offering an innovative solution for managing carbon emissions. When integrated into concrete, which is known for its prolonged lifespan can serve as an effective carbon sequestering agent. This integration, however, poses several challenges, including diminished workability, compromised strength due to the porous nature of biochar, and incompatibility with certain admixtures. While some of these challenges can be mitigated through process adjustments, fundamental interactions of carbon and concrete admixtures can lead to significant challenges with concrete performance. We present practical solutions to these challenges. Optimized air entrainer dosages have been established to address previously reported incompatibilities with commercially available Air Entraining Admixture (AEA). Additionally, this study examines the feasibility of using biochar in cement and concrete, highlighting both benefits and limitations.