Zhang, et al (2024) Preparation of high strength carbon negative building material by CO₂ curing biochar- EAF steel slag compacts. Construction and Building Materials. https://doi.org/10.1016/j.conbuildmat.2024.137456

A recent study published in Construction and Building Materials explores a novel method to create high-strength, carbon-negative building materials. The researchers focused on utilizing electric arc furnace (EAF) steel slag, a byproduct of the steel industry, combined with 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, to enhance the carbonation process. This approach not only strengthens the material but also helps sequester CO2, contributing to environmental sustainability.

EAF steel slag is an alkaline solid waste that can effectively absorb CO2 during carbonation, a process where CO2 reacts with the material to form stable carbonates. However, the dense nature of steel slag often limits CO2 diffusion, reducing the material’s strength and carbonation efficiency. To address this, the study introduced porous biochar into the steel slag mixture, which improved pore connectivity and facilitated CO2 diffusion.

The team systematically analyzed the effects of carbonation time, compaction pressure, and biochar content on the performance of the steel slag compacts. Their findings revealed that adding 5% biochar to the slag increased both the compressive strength and CO2 uptake by 24.6% and 1.3%, respectively. An empirical equation was also developed to predict the carbonation depth, enhancing the understanding of CO2 diffusion mechanisms within the compacts.

This research highlights the potential of using EAF steel slag and biochar to produce sustainable building materials. By promoting the reuse of industrial byproducts and enhancing CO2 sequestration, this method offers significant environmental and economic benefits. This innovative approach could play a crucial role in reducing the carbon footprint of the construction industry and advancing sustainable development.