|
Billions of dollars worth of structures are literally eaten
away by corrosion. To fight this destruction, a NASA Space Act
agreement merged Kennedy Space Center (KSC) research, tied to
electrical treatments of structural corrosion, with chemical
processes developed by Surtreat Southeast, Inc., of Cape Canaveral,
Florida.
KSC materials scientists became experts regarding an electrical
treatment known as electromigration. This procedure sends corrosion-inhibiting
ions to the rebar, or steel bars within a concrete slab, to prevent
it from rusting, corroding and separating from the concrete.
| The cracked (spalled)
concrete must be chipped away and replaced. The Surtreat chemical
is sprayed on the concrete and exposed steel bars. |

| Salty sea breezes create
spalling on Florida's concrete balconies. The salt migrates down
to the steel reinforcing bars, rusting the bars and cracking
the concrete. The edges and surfaces get unsightly and structural
damage occurs in support columns |
The issue was coming up with a viable treatment that can be
repeatedly applied to counter the Florida clime-- a mix of salt,
moisture, and baking sun. While that trio adds up to an ideal
situation for tourists, it's a triple-header threat to launch
pads, as well as miles of beachfront condos and other buildings.
Indeed, the aging oceanfront condominium market, as well as
seaside commercial buildings, are in constant need of upkeep
and restoration. The steel reinforcement bars--called rebars--that
are embedded in concrete patio floors of beachside condo units
have been particularly hard hit. Cracks and splitting of the
concrete are major headaches. Cracks allow more water, more salt,
and more acid to enter. Penetration accelerates, causing larger
cracks and spalling. This troublesome material malady hits many
concrete structures with decks that face the beach. Balconies
in Florida have been deteriorating at a rapid pace.
With the help of Florida's Technology Research and Development
Authority, an independent state agency that partners with KSC
in technology transfer initiatives, Surtreat Southeast approached
KSC with a chemical option to fight structural corrosion. Surtreat's
GPHP product is applied to the surface of a corroding concrete
slab and then seeps through to the rebar, coating it and preventing
further corrosion.
"It corrects the chemical imbalance that causes the rebar
to corrode. Traditional structural repair methods only last a
couple of years," explains Jim Emory, president of Surtreat
Southeast.
Emory explains that concrete, due to aging and other factors,
loses its pH, or acidity value. Poured concrete has a high pH
value of 11, 12, or 13. That high value can inhibit corrosion.
The aging of the concrete is a natural process in which the pH
starts to drop. When the pH value dips into the 8 to 9 range,
there is potential for corrosion of the reinforcing bars, he
points out.
Combining Surtreat's GPHP with electromigration fit well in
the KSC dual use program, part of NASA's technology transfer
and commercialization effort. That combination is expected to
result in a unique process with broad corrosion control applications.
Saving money by NASA and others is anticipated by creating a
structural repair method that lasts longer than just a couple
of years.
The cooperative effort involved Surtreat providing to NASA
the corrosion-inhibiting chemical and concrete test slabs, along
with technical and staff support as needed. From KSC, testing
specifications and procedures were provided. The NASA center
also prepared the test slabs with the Surtreat chemical and carried
out an environmental evaluation of the treatment. KSC materials
scientists reviewed the applicability of the chemical treatment
to the electromigration process and is preparing a report on
its effectiveness following a 12-month test program.
The results could have national importance, says Rupert Lee,
the NASA project engineer leading the joint effort. "Any
breakthrough in corrosion mitigation technology will have a significant
impact on the integrity of this nation's infrastructure,"
he explains.
|