The Moon's surface is kind of a pain to work with. Gazillions of years of micrometeorite hits and solar radiation has ground the rocks on the lunar surface into dust called regolith, and it's several centimeters thick. It gets into everything, clogging up machinery, and may even be hazardous to human health if it gets breathed in (it mixes with fluids and turns basically into concrete).
He used a simulated lunar regolith to create a concrete-like substance that's very hard and thermally resistant to flexure (it doesn't change its shape when you heat and cool it). It has a ton of potential uses... like, oh, say, if you coat it with something reflective it would make a pretty decent telescope mirror.
This is a fantastic idea. If we're going to live on the Moon anyway, then using the materials that are already there helps a lot. Lifting a big mirror to the Moon would cost a fortune, but using the regolith that's just sitting there saves a huge amount of time, effort, and of course money. The idea to use in situ materials has been around a long time, but Chen's new material may be a firm step in actually being able to implement this.
Imagine! In the lower gravity, much larger telescopes can be built. It wouldn't be easy -- in fact, it would be a considerable pain -- to manufacture a 50 meter optical telescope on the Moon. For comparison, the biggest telescope with a mirror on Earth is (are?) the twin ten-meter Keck 'scopes in Hawaii. But still, being able to scoop up dust on the Moon to create the mirror (and probably other parts as well like the foundation and structure) for a telescope like that would make it a far sight easier.
In fact, if you want to think really big, why not coat an entire crater? They're close to the right shape to start with... and you could wind up with a telescope hundreds of meters across!
And once we're there to stay, a project like that would, literally, be dirt cheap.
Image credit: NASA