Sustainable concrete structures by optimising structural and concrete mix design

ABSTRACT

Sustainable concrete construction can be achieved by combining optimised structural designs with low-carbon concrete (LCC). This paper demonstrates the importance of sustainable construction by analysing various design options for a typical suspended slab system in high-rise buildings. Pearson (2020) noted that concrete slabs make up approximately 47% of the embodied carbon (EC) in commercial and residential structures, with slabs alone comprising around 70% of the total concrete volume in residential buildings. This presents an opportunity to reduce EC through structural design choices. The analysis in this paper involved designing a post-tensioned (PT) flat slab system for a residential development in Sydney and then re-designing it as a reinforced concrete (RC) slab by adjusting slab thickness and reinforcement system. A key finding was that transitioning from an RC to a PT slab resulted in a 44% total EC reduction when using a 100% General Purpose Cement (GPC) blend. Further EC reductions can be achieved by implementing LCC. The chosen LCC blend for this study is 23% Fly Ash, 23% Ground Granulated Blast Furnace Slag, and 54% Cement (FA/GGBFS/GPC), demonstrating a 36% reduction in EC compared to a 100% GPC blend while maintaining acceptable workability, constructability, mechanical, and durability properties.

KEYWORDS:

• Structural optimisation
• sustainable construction
• embodied carbon
• low-carbon concrete
• reinforced concrete slabs
• post-tensioned slabs

Acknowledgments

The author would like to sincerely thank Daksh Baweja for his suggestions during the completion of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).