Optimization of biochar and fly ash to improve mechanical properties and CO2 sequestration in cement mortar

• Published in: Construction & building materials 2023-08, Vol.392, p.132021, Article 132021
• Main Authors: Mishra, Geetika, Danoglidis, Panagiotis, Shah, Surendra P., Konsta-Gdoutos, Maria
• Format: Article
• Language: English
• Subjects: Accelerated carbonation; Biochar; CO2 sequestration; Fly ash; Fracture properties
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.132021

•Addition of biochar enhances carbon sequestration through carbonate mineralization.•Accelerated carbonation enables effective utilization of up to 5% biochar, enhancing mechanical properties and CO2 uptake potential.•Combining fly ash and biochar offers a promising solution for waste utilization and the development of sustainable, low-carbon cementitious materials.•Carbonation of biochar-enriched mortars improves fracture strength and modulus of elasticity. The novelty of this study is to find out the optimum amount of biochar and high calcium fly ash to improve mechanical performance and promote CO2 uptake in cement mortar. The potential of biochar-fly ash mixes was optimized using response surface methodology (RSM) considering the influence of different amounts of fly ash (FA), biochar (B), and their interactions to achieve the optimal mix design with improved performance and carbonate mineralization. Additionally, the effect on the mineralization of different polymorphs of calcium carbonate was also investigated. The experimental results indicate that the accelerated carbonation of high calcium fly ash mortar enriched with biochar enables the effective utilization of biochar up to 5% for enhancing both the mechanical properties and CO2 sequestration. However, under normal curing conditions, it was observed that the optimal amount of biochar that can be used is