Sustainable approaches for developing concrete and mortar using waste seashell

Abstract

A comprehensive experimental program was performed to recycle high contents of seashell waste as fine aggregate or cement substitution. This effort strongly contributes toward preserving natural resources and mitigating various toxic substances emitted into the atmosphere during cement manufacturing. The first part of this study was dedicated to study possibility of 100% fine aggregate substitution in mortars and concretes whose mechanical properties are comparable to those made by natural sand. Efficiency of this approach was demonstrated by representing several mortar/concrete compositions. In the second part, 10 types of blended cement, with binary composition of seashell powder (up to 30% by mass) and ordinary Portland cement (OPC), were prepared and their physical/chemical properties were studied in comparison with characteristics of OPC. Mortars made of these blended cements, were produced and their properties including water demand and compressive/flexural strength were characterised. All the blended cements presented 28-day compressive/flexural strength relatively close to that of OPC. Furthermore, incorporation of seashell powder resulted in extending setting times (advantageous for constructing in hot climate), and reducing water demand (beneficial for enhancing mechanical strength) of the mortars. The requirements specified by several standards were extensively used to ensure performance of the proposed sand and cements.

Keywords:

• Waste management
• seashell aggregate
• cement replacement
• cost competitive production
• sustainability

Acknowledgements

The authors wish to thank Dr. Ahmad Soltanzadeh and Professor Said Jalali for insightful discussions during preparation of this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors wish to acknowledge the funding provided by project FLOATIDE, reference POCI-01-0145-FEDER-028112, co-financed by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalization (COMPETE 2020), under Portugal 2020, and by the Fundação para a Ciência e a Tecnologia – FCT I.P.(National Agency for Science and Technology).