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Keeping those landings smooth
Airlines maintain heavy winter flight schedules in the harshest
weather conditions because of the efficacy of deicing and anti-icing
chemicals that are used on planes, runways, taxiways, and ramps.
The materials that keep those big birds in the air, though, may
be corroding the concrete in the tarmacs where they make their landings.
A research team at Clemson University, under the direction of civil
engineering professor, Prasad Rangaraju, Ph.D., P.E., recently accomplished
preliminary testing for the Innovative Pavement Research Foundation
(IPRF) and Federal Aviation Administration, in an attempt to determine
how these non-chloride deicing chemicals may be affecting airport
tarmacs.
Traditional deicing salts used on city, county and state highways
and bridges, while economically effective, are typically chloride-based
materials, and are notorious for their ability to initiate and accelerate
steel corrosion in reinforced concrete structures. Consequently,
the aviation industry has employed a variety of non-chloride based
materials as deicing/anti-icing agents.
While considerable research has been conducted in studying the detrimental
effects of chloride-based compounds on concrete, very little research
has been done on the influence of other de-icing agents.
“While results are preliminary, explains Dr. Rangaraju, we
believe that a very aggressive chemical reaction occurs when potassium
acetate deicer solution is used on concrete pavements. Further study
is needed to understand the role these chemicals play in initiating
and exacerbating the potential for deterioration in concretes with
susceptible aggregates.”
Alkali silica reaction (ASR) is a chemical reaction that occurs
between runway concretes and certain deicing compounds. ASR produces
an alkali-silica gel. Subsequent expansion of the gel by imbibing
water causes tensile stresses in the affected aggregates, leading
to cracking.
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