(CNN) You could say things are getting a little more concrete on the International Space Station.
The basic ingredients for concrete include sand, gravel and rocks mixed with a cement powder and water-based paste.
Astronauts participated in the Microgravity Investigation of Cement Solidification project to understand how the chemistry of concrete is changed by zero gravity, down to the microscopic structures inside it.
The space station mixtures were compared to samples mixed on Earth.
The cement paste on Earth ended up being more porous, which is intriguing because more open spaces in the concrete would affect its strength.
Understanding how concrete works in space has direct bearing on future plans regarding the moon and Mars, according to NASA.
There's currently an experiment on the space station looking at cement samples that include simulated lunar particles.