Discarded seashells, typically treated as waste, can be transformed into a low-carbon concrete ingredient, potentially cutting significant amounts of CO₂ from one of the world’s most polluting materials and helping drive more sustainable construction.

New findings from a team of researchers from the University of East London (UEL) suggest an unexpected solution to one of the construction industry’s biggest carbon problems.

The research offers a novel route to cutting the environmental burden of cement, which is responsible for around seven per cent of global carbon emissions. 

Microstructural

By grinding discarded scallop-shells into fine powders and substituting them for part of the cement mix, the team achieved carbon reductions of up to 36 per cent - while keeping most of the concrete’s core performance features intact.

The study - Experimental Investigation of Low Carbon Concrete Using Ground Seashell Powder as Filler and Partial Cement Replacement - demonstrates that shells, once processed into two fine powder grades, can act as both a filler and a partial cement substitute.

Dr Ali Abass, Associate Professor of Structural Engineering at UEL and study lead, said the findings highlight a promising opportunity for industry. “Concrete is everywhere, and consequently its carbon footprint is enormous. 

"What we’ve shown is that something as ordinary as discarded shells can make a meaningful dent in those emissions. At moderate replacement levels the concrete behaves very well, which means this could be scaled up in real-world settings.”

The team’s microstructural analysis revealed that the calcium-rich shells help refine the pore structure of the concrete and support the formation of additional binding compounds, offering further performance benefits.

Backbone

“Millions of tonnes of shell waste are produced globally each year, and most of it has no useful destination,” Dr Abass added. “If we can divert even a fraction of that into low-carbon construction materials, the environmental gains could be significant. It’s a simple idea with real potential to reshape part of the sector.”

The potential for adoption across the construction sector is considerable, particularly as tighter environmental standards and whole-life carbon reporting become more prevalent. 

With infrastructure and building contractors under growing pressure to decarbonise supply chains, the use of naturally derived waste materials could offer an accessible route to measurable reductions.

If further industry trials confirm the material’s reliability at scale, shell-derived concrete could support a shift towards more circular economic models, in which waste streams from one industry feed directly into another.

As Dr Abass added: “A future where yesterday’s coastal by-product becomes tomorrow’s structural backbone isn’t far-fetched - it’s practical, cost-effective, and increasingly necessary.”

This Author

Brendan Montague is an editor of The Ecologist.