Mechanical properties and microstructural characterization of ferrock as CO2–negative material in self-compacting concrete

Abstract

The construction industry is one of the major sources of pollution and global warming, with the utilization of cement being a significant contributor. This study aimed to minimize cement usage in construction while maintaining overall strength through the development of sustainable and eco-friendly concrete. A self-compacting concrete (SCC) was created by replacing cement with eco-friendly ferrock, aggregates and superplasticizers at levels of 5%, 10%, 15%, 20% and 25%. The optimal blend was determined based on fresh and mechanical behaviour parameters. Rheological analysis of the fresh concrete was conducted using L-box, Slump cone, V-funnel equipment and visual stability index. The SCC was then cured through water immersion, CO2 exposure and a combination of both. The performance of the ferrock SCC was evaluated under different curing conditions to determine its hardened and microstructural properties. The addition of ferrock altered the properties of the concrete, and changing the curing method also influenced the behaviour of the hardened concrete. CO2 curing achieved about 40% of the concrete strength within four hours, while combined water and CO2 curing produced higher-quality concrete, as shown by UPV, SEM, and XRD results. The incorporation of ferrock almost doubled the strength of the concrete in combined curing. At an optimum replacement level of 10%, the compressive strength values of water, CO2, and combined curing increased by 21.9%, 25.9% and 32.6%, respectively, after 28 days. The bond strength also increased by 20% at this level of ferrock addition for combined curing. Comparison with normal SCC indicated that the ferrock-based SCC was physically stronger at an optimum replacement level of 10%, with a higher degree of compaction and dense matrix. These findings suggest the superiority of ferrock SCC, which offers potential for use in future construction.