I don't understand a single word of this but it sounds so cool, I just had to share it.

Explaining the product, glass bubbles, in detail, Arco said, "The hollow glass spheres are microscopic particles used to decrease the density of cement slurries."

The same weight reduction technology also finds applications in the construction of buoyancy modules and as a thermal insulation component for flow assurance in offshore operations. The hollow glass spheres represent apparently a simple, efficient and effective way to deal with density reduction.

Arco also sees the product as being environmentally inert and very safe compared to alternative methods to lighten cement slurries that involve energised gases and the associated handling and safety problems with these systems.

Read it all here.