Ever wonder how modern concrete structures become dilapidated after only a few decades while Roman concrete structures which were built over a thousand years ago still stand today? Well, apparently, it involved some “secret ingredients” in the concrete mix.
Early this year, it was revealed that researchers from MIT, Harvard University, and laboratories in Italy and Switzerland have reverse-engineered the formula for Roman concrete, and solved the riddle of why Roman concrete is so durable.
Years before, scientists have learned that mixing concrete with seawater instead of fresh water was part of the Roman’s “secret recipe” (well, may not so much of a secret for the Romans at that time…) but in a recent study published by MIT, it was revealed that seawater alone ain’t it.
There’s a thing called quicklime that may be responsible for durability and even self-healing. Yes. You heard that right. Self-healing concrete. It sounds super sci-fi-ish but rest assured this is very real.
Anyhoo, quicklime reacts with seawater, resulting in a hot chemical reaction that leaves undissolved lime in the mixture. That there, my friend is where the magic happens.
When cracks showed up, rainwater gets into these cracks and comes into contact with the lime chunks. This reactivates the cement which fills the gaps and thereby closes up the cracks and self-healing is achieved. I know right. It is crazy (in a good way).
This revelation means we could have more durable concrete structures in the future, and it is good news for the environment too. In 2021, the cement industry contributed 8% of greenhouse gas emissions, and therefore, if concrete could self-heal, it could alleviate the environmental concerns since little to no repair will be required for concrete roads and structures. Now, tell me if that isn’t super cool news.
You may learn more in an article posted on MIT News and on the paper the research team published on Science Advances in January this year.
Featured Photo by Evan Qu on Unsplash.
Images: MIT.
