Rock to Road

Turning cement into metal

May 28, 2013
By Aggregates and Roadbuilding

May 28, 2013, Lemont, Ill.
– Scientists have found the formula for turning liquid cement into liquid
metal. The process makes cement a semi-conductor and opens up its use in the electronics
marketplace for thin films, protective coatings, and computer chips.

The change demonstrates a
unique way to make metallic-glass material, which has positive attributes including
– resistance to corrosion, less brittleness than traditional glass,
conductivity, low energy loss in magnetic fields, and fluidity for ease of
processing and molding.

Previously only metals have
been able to transition to a metallic-glass form. Cement does this by a process
called electron trapping, seen only in ammonia solutions before this.

The team, Chris
Benmore, a physicist from the U.S. Department of Energy's Argonne National
Laboratory, and scientists from Japan, Finland, and Germany, studied mayenite, a component of
alumina cement made of calcium and aluminum oxides. They melted it at
temperatures of 2,000 C using an aerodynamic levitator with carbon dioxide
laser beam heating.


The material was processed
in different atmospheres to control the way that oxygen bonds in the resulting
glass. The levitator keeps the hot liquid from touching any container surfaces
and forming crystals. This let the liquid cool into glassy state that can trap
electrons in the way needed for electronic conduction.

The scientists discovered
that the conductivity was created when the free electrons were
"trapped" in the cage-like structures that form in the glass.