People think concrete is about strength. It is about time. From the moment the plant loads my drum, the mix has about ninety minutes before it starts to set. Ninety minutes to cross a city at seven in the morning, find a gate that matches the address, and wait while a foreman decides whether today is the day.
I have poured the floors of hospitals and the foundations of car parks. I have poured a swimming pool for a man who argued about the colour of grey. I have driven home with a full drum because the rain came, and watched them wash four thousand euros of concrete into a skip.
So when people talk about the future of concrete, I think about that skip. The greenest concrete is the one you don't waste. The second greenest is the one already standing. Leave it there. Go and have a coffee instead.