TM 5-822-7/AFM 88-6, Chap. 8
APPENDIX B
THIN BONDED RIGID OVERLAYS FOR RIGID PAVEMENTS
strength, modulus value, and thermal character-
B-1. Application. This appendix contains additional
istics. It should also be remembered that the
information and instructions for preparing contract
surface of the concrete is exposed to traffic and
specifications for thin bonded overlays for rigid
weather and should be of high quality. Beyond this,
pavements. A thin bonded overlay is generally for
the same guidance given for normal portland cement
correction of surface problems, such as scaling or
concrete applies.
skid resistance, rather than structural upgrading of
the pavement.
B-7. Preparing the existing pavements. After any
B-2. General. Although the volume of concrete
necessary repairs and slab requirements, the
required for a thin bonded overlay is comparatively
existing pavement surface must be thoroughly
small, this surface layer is the portion exposed to
cleaned of all deteriorated concrete, oil, grease, and
traffic and weathering and must be of the highest
dirt. In order to thoroughly clean the surface, it is
possible quality. A complete bond must be obtained
recommended that rotary-type grinders be used to
between the rigid pavement and the overlay. The
remove at least 1/4 inch of the existing concrete, and
thickness of the overlay will be not less than 2 inches
in areas where the concrete has deteriorated, the
but not more than 5 inches. The required thickness of
material should be removed to sound concrete. After
a thin bonded overlay for strengthening roads and
grinding with rotary grinders, the surface should be
streets will be determined in accordance with TM 5-
sandblasted to remove debris left from grinding.
822-6/AFM 88-7, chapter 1.*
Before the pavement is placed, the surface of the
existing pavement should be cleaned by brooming
and followed with compressed air. In areas where
B-3. Correction of defects in existing pavement. A
equipment turns, such as trucks hauling concrete,
condition survey should be made and the cause of
the existing pavement should be covered with sand or
cracking of slabs determined in order to develop an
some other protective cover to prevent rubber from
appropriate repair prior to overlaying. The existing
scrubbing off of tires onto the existing concrete and
pavement must be in good structural condition, and
forming a bond breaker.
any broken or otherwise defective slabs will be repaired
or replaced before the overlay is applied. The
designer of the overlay should realize that cracks in
B-8. Placement of overlay. Either a neat cement
the pavement being overlayed will likely reflect
slurry or cement and sand grout is satisfactory for
through the overlay pavement.
bonding the overlay to the existing surface. These
may be applied by pressure spraying or by brooming
over the existing surface, but they should be applied
B-4. Flexural strength. In general, flexural strength
to a dry surface and applied only 6 to 10 feet ahead of
for the thin bonded overlay should be about the same
concrete placing. If the grout or slurry dries before
as that obtained for the original pavement construc-
concrete is placed, it should be removed and fresh
tion at the corresponding age.
material applied. The concrete should be placed,
finished, textured, and cured using normal procedures.
B-5. Aggregate sizes. The nominal maximum size
Joints in the overlay must coincide with the joints in
aggregate used will not exceed one-fourth of the
the base pavement.
overlay thickness.
B-6. Mixture proportioning. It is desirable for the
paid by the square yard of overlay placed.
thin bonded overlay to be as similar as possible in
* References are listed in Appendix A.
B-1
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