UFC 3-270-04
15 March 2001
problem. Proper patching procedures for spalls and popouts must be meticulously followed, and
the repair material should have similar thermal characteristics to the original concrete. Even so,
the repairs may only be temporary. Overlays using heat resistant concrete are a potential repair
for scaled areas or for areas with concrete of poor heat resistance. If scaling is due to a paste on
a concrete surface that is otherwise acceptable, grinding the surface may be adequate. Joint
sealant used in concrete pavements exposed to high temperatures should conform to Federal
Specification, SS-S-200E. This specification does require testing of the material at 500 degrees
Fahrenheit (260 degrees Celsius) for 2 minutes so that some resistance to high temperatures can
be achieved. However, when high temperatures are combined with jet blast, the sealant may still
be damaged or blown out of the joint. Under these circumstances, increased periodic resealing
must be accepted as routine maintenance. Conventional concrete and joint sealants should
provide reasonable service up to concrete temperatures of about 500 degrees Fahrenheit
(260 degrees Celsius).
Above this temperature, deterioration of concrete and increased loss of sealant can be expected.
High-quality concrete with selected aggregates can reduce the amount of damage. Above
1,000 degrees Fahrenheit (538 degrees Celsius), severe deterioration can be expected, and
refractory materials such as high alumina may be needed. Where possible, blast shields,
diverters, or increased slope of pavements should be used to allow the maximum dissipation of
the exhaust plumes temperature before it impinges on the concrete. Use of continuously
reinforced concrete for areas such as power check pads removes the need for joints and joint
sealants. In one installation, refractory brick was used to surface a test facility where
high-temperature engines were tested and evaluated. Conventional concrete has a limited
capability to withstand high temperatures for an extended period of time, and facilities must be
designed to accommodate these limitations.
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