A new experiment included mixing aqueous solution with tricalcium silicate for the first time – a scientific way of saying concrete. The basic ingredients for concrete include sand, gravel and stones mixed with a cement powder and water-based paste. It sounds as easy as whipping cake mix, but the process itself is much more difficult.
And the lack of gravity changes everything.
Astronauts participated in the Microgravity Investigation of Cement Solidification project to understand how concrete chemistry is changing with zero weight, down to the microscopic structures in it.
"How will it cure? the microstructure? "said Aleksandra Radlinska, principal investigator for the experiment at Pennsylvania State University. "These are the questions we are trying to answer."
A variety of mixtures were made where cement powders, additives, water and time grants varied. The researchers studied how the cement powder dissolved in the water because it is when the molecular structures shift to form coherent crystals.
The space station mixtures were compared with samples mixed on earth. The cement paste on the earth ended up being more porous, which is exciting because more open spaces in the concrete would affect its strength.
"Increased porosity has a direct impact on the strength of the material, but we have not yet measured the strength of the space-shaped material," Radlinska said. "Although concrete has been used for so long on earth, we still do not necessarily understand all aspects of the hydration process. Now we know that there are some differences between terrestrial and space-based systems and we can investigate those differences to see which ones are beneficial and which ones are harmful to using this material in space. "