Featuring Alastair Wilkinson | Conversations with Agents of Change Podcast
Walk down any street and look around. The pavement under your feet. The walls of your home. The school down the road. The hospital, the bridge, the city skyline. Almost everything you see has one thing in common: cement.
It’s so ordinary we barely notice it. And yet it quietly holds up modern civilisation.
But here’s the part most of us don’t realise:
Cement is responsible for around 7–8% of global CO₂ emissions, making it one of the biggest contributors to climate change in the built environment.
If we want truly sustainable construction, we can’t just electrify cars or install solar panels.
We have to rethink what we build the world with.
That’s exactly what this episode of Conversations with Agents of Change explores.
And at the centre of it is someone you might never expect to be leading climate action: a cement scientist.
An unlikely path into climate solutions
When Alastair Wilkinson talks about his career in sustainable materials, it doesn’t sound like a grand plan. There was no childhood dream of “decarbonising the cement industry.” He grew up around construction. His grandfather was a bricklayer. His father worked in building control. He imagined going into business — maybe even becoming an estate agent. Then life nudged him sideways. A university course. A PhD opportunity. A research project on low-carbon cement alternatives. Before he knew it, he was standing inside cement plants, asking one deceptively simple question: “How can we build the same world… with far less carbon?”
That question has shaped his entire career. Today, Alastair works at the intersection of cement decarbonisation, circular economy innovation, and sustainable building materials, helping one of the world’s most traditional industries rethink itself from the inside. Not through flashy disruption. Through practical, grounded change.
Why cement is so hard to decarbonise
If switching to renewable energy feels straightforward, cement is anything but.
Because the problem isn’t just fuel.
It’s chemistry.
To make cement, limestone is heated to extremely high temperatures. When that happens, the stone chemically releases carbon dioxide.
Even if every cement plant ran on 100% renewable energy tomorrow, much of the CO₂ would still be released.
It’s built into the process itself.
That’s what makes carbon reduction in the cement industry such a complex challenge — and why simple replacements don’t exist.
As Alastair explains, we can’t just “swap cement out” like we might swap plastic bags for paper.
We need smarter solutions.
The quiet revolution: low-carbon cement alternatives
Instead of trying to eliminate cement entirely, Alastair focuses on something more realistic:
Use less of it. Use it better. Replace what we can.
One of the most promising breakthroughs in low-carbon construction is something most of us would never think twice about:
Clay.
Specifically, calcined clay cement.
When certain clays are heated at lower temperatures, they become highly reactive materials that can replace a large portion of traditional clinker — the most carbon-intensive part of cement.
The results are impressive:
- Lower temperatures → less fuel
- Less limestone → fewer process emissions
- Up to 40% lower carbon footprint
- Similar strength and durability
And unlike many “green” innovations, clay isn’t rare or expensive.
It’s everywhere.
In fact, regions that struggle to produce conventional cement — like parts of Africa and South America — often have abundant clay resources.
Which means this isn’t just a sustainable construction material.
It’s a potential economic opportunity.
Local production. Fewer imports. Stronger communities.
Climate solutions that also make business sense.
What circular construction really looks like
When people hear “circular economy in construction,” they might picture futuristic materials or experimental buildings. But often, it’s surprisingly practical. Allastair describes something beautifully simple: Old concrete doesn’t have to be waste. It can be crushed, separated, reprocessed and used again. Even the cement paste itself can be recovered and reintroduced into new mixes. What used to go to landfill can become tomorrow’s road, bridge, or home. Inside many modern plants, waste isn’t waste anymore — it’s just future raw material. This is what green construction innovation looks like in real life: Less extraction. Less landfill. More reuse. Smarter systems. Not glamorous. But incredibly powerful at scale.
Change doesn’t always look like activism
When we talk about climate action, we often imagine protests, policy fights, or start-up founders pitching bold ideas. But this episode highlights another kind of change-maker. Someone working quietly inside the system, testing, adjusting, connecting with operators and making a bridge between research and reality.
Because a brilliant idea in a lab means nothing if no one on a construction site can actually use it.
Alastair calls himself a facilitator, someone who helps good ideas move from paper to practice. And maybe that’s what being an Agent of Change really means. Not shouting the loudest. But steadily reshaping the foundations beneath our feet.
Why this matters for the future of sustainable building
If we’re serious about:
- net zero cities
- sustainable infrastructure
- climate-resilient communities
- low-carbon construction
…then materials matter just as much as energy.
Because every building starts long before it’s visible.
It starts in quarries.
In kilns.
In chemistry labs.
In small process decisions most of us will never see.
The future of sustainability is being decided there, too.
And thanks to people like Alastair, that future looks a little more circular.
A little more practical.
A little more hopeful.
Listen to the full episode
Tune in to Conversations with Agents of Change to hear the full story of sustainable cement, circular construction, and decarbonising the materials that build our world.
Because sometimes the most powerful climate solutions aren’t flashy.
They’re foundational.
Literally.
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