UFC 3-260-02
30 June 2001
is a significant lag between exposure to an elevated temperature and heating of the concrete to that
temperature. Normal military aircraft operations do not heat concrete pavements to temperatures that
cause damage.
(2) Power Check Pads and Similar Facilities. If the jet engine exhaust plume is allowed to
impinge directly on the concrete surface, severe erosion can occur. This is a potential problem for
facilities such as power check pads where engines have to be operated for extended periods and where
the configuration of some aircraft will project the engine exhaust plume into contact the pavement
surface. For this reason, these facilities are often specifically designed to have larger slopes than
normal to keep the exhaust plume from directly impinging on the pavement surface. Pavement damage
can arise when parking ramps, old taxiways, etc. are converted to use as power check pads, and the
conventional slopes on these facilities allow the exhaust to come into direct contact with the pavement
surface.
(3) Pavements Exposed to Vertical/Short Take-Off and Landing Aircraft Exhaust. The
introduction of the Harrier aircraft exposed pavements to new higher levels of heat and blast than
conventional aircraft. This trend is likely to continue with development of new aircraft like the joint strike
fighter currently scheduled for deployment in about 2008. The Naval Facilities Engineering Services
Center has conducted extensive research in support of deployment of the Harrier in the Marine Corps.
They found that reinforced conventional concrete made with diabase aggregate has provided good
performance in the field for up to 15 years. Recent studies have also found that improved performance
could be achieved with portland-cement concrete with lightweight aggregate and nylon fibers, a
proprietary blended cement with lightweight aggregate, and nylon fibers, and a proprietary magnesium
phosphate cement with lightweight aggregate. The Naval Facilities Engineering Service Center, 1100
23rd Avenue, Port Hueneme, CA 93043-4370, should be contacted for current guidance and research
results in this area.
(4) Pavements Exposed to Auxiliary Power Unit (APU) Exhaust. The APU on the B-1, FA-18,
and certain models of aircraft currently under development are mounted so that the exhaust is directed
downward and into contact with the pavement surface. With extended operation of these units, the
surface of the concrete may be heated to temperatures approaching 177oC (350oF). This leads to
scaling and spalling in the limited area around the exhaust impingement area. Studies by the Naval
Engineering Service Center, Air Force Wright Laboratories, and the U.S. Army Engineer Research and
Development Center have identified two mechanisms contributing to this damage. Repeated heating
and cooling lead to thermal fatigue and surface failure. At these elevated temperatures, fluids high in
esters such as fuel, lubricants, and hydraulic fluids can chemically react with portland-cement concrete
and lead to scaling of the pavement. In parking areas for these aircraft, the APU exhaust impinges on
the concrete where there is significant collection of these fluids that have leaked from the aircraft in
normal maintenance and operation. At present there is no technical solution to this problem. Ad-hoc
solutions and trials in the field have included bolting steel plates to the pavement in the area where the
exhaust contacts the pavement, various coatings, refractory concretes, and specialty concretes with
generally mixed or unsatisfactory results. HQUSACE (CEMP-ET), appropriate Air Force MAJCOM
pavements engineer, or Naval Facilities Engineering Service Center should be contacted for guidance
when designing parking areas for these aircraft.
g. Specification and Construction. It is crucial that proper material and construction specifications
be developed to accompany the thickness design and geometric design and detailing. There have been
numerous problems with military concrete airfield pavements in recent decades as the result of improper
construction techniques, poor finishing, inadequate curing, late saw-cutting of joints, use of aggregates
susceptible to alkali-aggregate reactions without proper countermeasures, inclusion of deleterious
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