TM 5-822-11/AFP 88-6, Chap. 7
CHAPTER 2
SEALANT MATERIALS
2-1. General. This chapter provides guidance
cause the affected slabs to crack.
for the selection of sealants, the functions of each
(4) In bituminous pavement, the heaving of
sealant, and the background needed to understand
the pavement at the cracks due to frozen moisture
sealant performance and quality control required
results in increased surface roughness. The satu-
to produce a sealing project with satisfactory per-
rated base or subbase material allows high deflec-
formance. Appendix B provides comparisons be-
tions under wheel loading which causes additional
tween American Society for Testing and Materials
cracking of the pavement.
(ASTM) and Federal Specifications (FS).
b. The second function of the sealant is to
prevent the retention of incompressibles in the
2-2. Sealant Functions.
joint or crack. There are several pavement dis-
a. There are two primary functions of joint and
tresses associated with the retention of incom-
crack sealants. The first is to prevent surface
pressibles in joints and cracks. When the pave-
water from seeping through the pavement struc-
ment contracts during low temperatures, the joints
ture into underlying water susceptible soils or base
and cracks open, allowing incompressible materi-
courses, and the second is to prevent the retention
als to fill the available space. As the temperature
of incompressibles in the joint or crack. Both of
increases, the pavement expands, However, the
these functions are extremely important in
expansion is restricted by the incompressibles that
preventing premature pavement failure by main-
have filled the joint and crack openings. In con-
taining pavement durability and structural integ-
crete pavement, the restricted movement causes
rity. A discussion of each function is given on the
spalling, and, in severe cases, blowups. In bitumi-
following pages.
nous pavement, it causes upward tenting at the
(1) Water seepage must be prevented from
cracks. On airfield pavement, the retention of
entering into water susceptible soils such as those
debris and incompressibles in joints create a
with a high fines content or a high plasticity index
potential for FOD to aircraft.
(PI). If water is allowed to penetrate into the
2-3.
Sealant Types.
water susceptible soil foundation of a pavement,
the increased moisture content leads to a decrease
a. The three types of sealant materials used
in soil strength. For portland cement concrete
when sealing or resealing joints are field-poured
(PCC) pavement, the water seepage reduces the
(field molded) hot-applied, field-poured (field
subgrade support which may lead to pumping,
molded) cold-applied, and preformed elastomeric
corner breaks, shattered slabs, and other load
seals. The type of sealant that should be used for
associated distresses. For bituminous pavement, a
a project is determined from several
reduction in foundation strength produces the
considerations including the type of pavement,
appearance of alligator or fatigue cracking.
joint design, joint or crack condition,
(2) Water infiltration into PCC can also
environment, cost, and the use of the pavement
lead to the loss of durability. The progressive loss
section in question. A typical joint which indicates
of durability, commonly called "D-cracking," is a
the appropriate terminology used in discussing a
moisture-freeze-thaw aggregate interaction that
joint is shown in figure 2-1.
destroys the structure of the concrete. This type of
b. Field-poured sealant materials are liquid at
deterioration is often found where low-quality car-
the time of application and solidify by either
bonate rocks are used as concrete aggregate and is
cooling or by a physical or chemical reaction. The
common where moisture and temperature condi-
hot-applied sealants which solidify by cooling are
tions produce the moisture-freeze-thaw cycles nec-
referred to as thermoplastic type materials. Hot-
essary for deterioration. The weakening of the
applied sealants that react when heated to solidify
concrete around joints and cracks leads to poten-
are referred to as thermosetting materials. The
tial spalling of the concrete, increased roughness,
cold-applied sealants solidify by a chemical reac-
and increased foreign object damage (FOD).
tion between two components or a physical reac-
(3) The seepage water may also contain
tion, such as solvent evaporation. Sealants may be
deicing salts or chemicals that cause load
further classified as either jet-fuel resistant (JFR)
transferring steel dowels to corrode. The corroded
or non-JFR. JFR sealants are normally a tar based
dowels lock up and prevent the slabs from moving
material while non-JFR sealants are normally
in response to temperature changes which in turn
asphalt based materials. The base material for the
2-1
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