NUL Student Creates Cement out of Clay!

The cement sticks to a brick like a glue! ‘Mateko Nchai, a fifth-year student at the National University of Lesotho (NUL), has made a cement made from local clay that hardens around a brick to protect it! Unlike similar cements, her cement hardens at room temperature! Although she developed it for coating, it can be used in many other applications. She created it while working with an organization called RISE International.

This is how it all started!

RISE is experimenting with building strong houses using compressed earth bricks—bricks made mostly of soil. Those are low cost bricks. They use locally available soils.

But these bricks need protection from rain and air, otherwise they might weaken over time. Compared to traditional mud bricks, they are stronger as they are made with superior technology but still, they need protection.

In the past, Basotho used a mix of soil and cow dung to cover their mud houses. It worked, but people had to apply it again and again, year in, year out.

‘Mateko wanted something better—something that would last longer but still use materials found in Lesotho.

So, she chose clay. Clay is an amazing material but the quality of the one found in Mefeteng is, as she puts it, “on its own lane”. So she used that one for her experiments.

How she created the cement is much more complex than we explain here. But we will give you the hint, just so you have an idea.

She heated the clay at around 800 °C. That’s much cooler than the 1500 °C needed to make normal cement. Heating the clay in this way changed its structure, making it ready to mix with water and a few safe chemicals.

When she added everything together, the clay mixture turned into a smooth paste. That’s no normal paste. As it hardens it forms in inside structure like that of plastic. Well, it’s not plastic but it is built on the same building blocks. “That’s what makes it hard,” she said.

She put it on the surface of soil bricks—and something amazing happened. It hardened! No need for a big oven. No need for extra heat. It just dried and turned into a strong shell.

“The coating became so hard, I couldn’t believe it,” ‘Mateko said. “It stuck to the brick like a second skin!” She said she expected future researchers to find how durable the coating will be.

This kind of cement is different from the one you know, the normal grey stuff. It uses less energy, and it produces much less pollution. That’s good news for the planet!

Normal cement is a big problem for the environment. Every time we make one kilogram of it, we also release nearly one kilogram of carbon dioxide gas into the air. That gas makes climate change worse.

But ‘Mateko’s clay cement uses less heat and creates fewer emissions. It’s a cleaner, smarter choice for building in Lesotho—and maybe in many other countries too.
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