powdery nature of lunar soil actually makes it a
good ingredient for concrete
because it would create a
substance that would
within the cementitious material, according to Toutanji.
finer the material,
the more homogeneous the material will be, and homogeneity
usually provides more strength."
plans to launch manned spacecraft to moon in 2020;
hopes not just to
land on the moon but also to establish longer-term bases for
astronauts, and to
accomplish this the astronauts will need to be able to build structures
resources that are readily available on the lunar surface. The structures will
need to be able to withstand the harsh lunar environment, and for this
concrete appears to be a suitable building material.
comprises a binder—cement and water—mixed with
aggregates, but water will
presumably be unavailable on the moon.
Houssam A. Toutanji, F.ASCE, a
professor at The
University of Alabama in
Ph.D., a geological engineer at the National Aeronautics and Space
Administration’s Marshall Space Flight Center, in Huntsville,
published an article (Unconventional
Approach. Civil Engineering,
a concept of
creating concrete structures on the lunar surface without the use of
is searching for a means to use resources that are
available from the surface of the moon, according to Toutanji.
of transporting materials from Earth will place a premium on
and ingenuity,” he
said. He anticipates concrete
to play a major role in
constructing facilities on the lunar surface to survive the harsh
on the Moon’s surface.
Toutanji says that raw materials needed to
on the moon exist in abundance.
As a matter of fact, he
on the moon has a good chance of being stronger than concrete made on
concocted a number of "recipes"
and formed small strips of lunar
concrete. He then subjected those samples
to various types of tests, such as
heat, compression and tension.
Toutanji's research so far shows a concrete that is 45 percent
experiments reveal that concrete produced from lunar soil could
pressure of 5,800 pounds per square inch, compared with 4,000 psi for
concrete on Earth.
the lunar soil provides most of the raw materials
needed to make concrete, a binding agent is required. On Earth, cement
water are used as that binding agent. Obviously,
water is not as
the moon." The
idea that water exists on the moon is open to discussion.
Even if we can find water, it will be such a precious commodity; it
more valuable for use in other applications."
In recent months, Toutanji's research has pointed him in a different
for a binding agent. It took four years, but he has produced a breakthrough
that would allow astronauts to produce concrete without water.
began looking at the
approach of making concrete without water,"
he said. "We used the Dry-Mix/Steam-Injected method to produce
We found that this method offers advantages, such as shorter hydration
higher strength, and less cement and water consumption." Then, he began
with sulfur to bind the simulant lunar dust together to form the
"We used only sulfur and simulant
lunar soil in concrete. We
have known that sulfur is useful as a binding material and sulfur
concrete has been used on Earth in a number of applications." .
Waterless concrete, also
sulfur concrete, is not
a true concrete in the traditional sense because very little in the way
chemical reaction occurs between the components.
this well-established, albeit expensive, building
corrosive environments in highly acidic or salty areas.
create it, one melts sulfur, which in this case acts like a
material, and mixes it with an aggregate. The mixture is then poured,
and allowed to harden. Sulfur
concrete usually contains 12 to 22 percent sulfur
by mass and 78 to 88 percent aggregate by mass.
aggregate is very important in determining the right mix with the best
mechanical properties. The
also contain plasticizers (5 percent), and the aggregate can include
said sulfur is found in abundance on the moon's
surface. "The sulfur content of the lunar regolith is mainly controlled
troilite (FeS), and extracting sulfur from the lunar soil is possible
series of chemical processes." Thus, making the prospects of
permanent structures on the moon proves to be plausible.
Fiberglass can be used as
reinforcement of sulfur
concrete to improve its tensile and flexural strength.
Fiberglass formation on
the lunar surface is feasible because the material could be produced
from the lunar soil or from the by-products obtained in extracting such
as aluminum and titanium. The
addition of silica appears to increase the
compressive strength of sulfur concrete.
silica sulfur concrete
seemed to exhibit a more brittle failure
However, Toutanji is quick to point out that many questions remain.
is going to be
simple on the moon. Questions remain about the
extreme ambient temperature conditions, cosmic radiation,
well as simple issues, such as how would a concrete structure be
At the same time, scientists
already knew that producing concrete in a
microgravity environment does not harm the strength of the concrete.
a 1994 University of Alabama in Huntsville experiment aboard the space
shuttle Endeavor showed that
microgravity has the opposite effect. The
scientists found that a lack
gravity produced fewer voids in the concrete and the material was just
of low gravity and fine lunar dust could result
in a strong concrete."