Performance of sustainable mortars containing blast furnace slag and fine concrete waste: an environmental perspective

Abstract

About 9% of the globe’s carbon dioxide (CO₂) emissions are attributed to cement production. The replacement of cement with blast furnace slag and fine concrete waste (FCW) could reduce the CO₂ emissions associated with the construction sector. Consequently, the main objective of the current study is to examine the combined effect of blast furnace slag and FCW on mortar manufacturing. The experimental study was conducted in three stages. In stage I, mortars were prepared using cement-to-sand ratio of 1:3. The cement was substituted with FCW at 0.00, 0.30, 0.60 and 0.75 fractions. From the Stage I results, a mortar mixture prepared with 60% FCW and 40% cement was chosen for the Stage II study. In place of cement, slag was used in fractions of 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25. The strengths of the mortars were significantly enhanced when slag was employed as a replacement for cement. In the final stage of the study, the environmental impact (EI) of producing FCW was evaluated. The results show that the EI values for producing FCW are far below those of cement and slag. For instance, the global warming potentials of producing cement, slag, and FCW were 0.951 kgCO₂eq, 0.0188 kgCO₂eq and 0.0169 kgCO₂eq, respectively. In conclusion, the produced mortars provided the specified strength requirements for masonry works as well as environmental and economic benefits, making them sustainable.

Keywords:

• Fine concrete waste
• sustainable mortars
• slag
• cementitious materials

REVIEWING EDITOR:

• Ian Phillip Jones
• University of Birmingham
• UK

SUBJECTS:

• Testing
• Materials Science
• Civil, Environmental and Geotechnical Engineering

Acknowledgements

This article is part of the doctoral study of Eric A. Ohemeng. The authors appreciate the contribution and support of the technicians at the laboratory of the Civil Engineering Science Department, University of Johannesburg.

Author contributions

Eric A. Ohemeng: conceptualization, data curation, formal analysis, investigation, methodology, visualization, writing – original draft preparation, and editing. Molusiwa S. Ramabodu: conceptualization, review, editing, and supervision. Tholang D. Nena: conceptualization, review, and editing. Yana Kancheva: conceptualization, review, and editing. All authors read and approved the final manuscript.

Disclosure statement

The authors declare that we have no potential conflict of interest.

Data availability statement

The datasets used and/or analysed during the current study are available from the corresponding authors upon reasonable request.

Additional information

Funding

The authors received no direct funding for this research.