TM 5-822-7/AFM 88-6, Chap. 8
used, they should conform to ASTM A 775. Epoxy-
encountered in pavement construction. The use of
coated dowels and reinforcing steel will rest on
fly ash, however, is becoming increasingly common.
Fly ash produced by industrial burning of coal tends
epoxy-coated wire bar supports or on bar supports
to be highly variable, depending on factors such as
made of dielectric material. Wire bar supports will
be coated for a minimum of 2 inches from the point
emission controls, load, and boiler design. This
production variability is compounded further by the
of contact with the epoxy-coated reinforcing bars.
natural variability of lignite and subbituminous coal
Adequate ventilation to dissipate fumes must be
provided if epoxy-coated steel is welded.
that produce Class C pozzolan. Also, Class C
d. Appendix C describes the materials and
pozzolans have poor resistance to sulfate attack,
methods used for the construction of steel fiber
and some have high alkali contents that may contri-
reinforced concrete.
bute to alkali aggregate reaction. Specifications for
pozzolans should require that the ASTM C 618
specification be modified to require a maximum loss
9. Water. Water for mixing concrete will be free from
materials that affect hydration of the cement.
on ignition of 6 and 8 percent, respectively, for Class
F and N pozzolans and a minimum pozzolanic activity
Potable water may be used without testing however,
index with lime of 900 psi at 7 days. Mixture propor-
tests will be made in accordance with CRD-C 400 if
tioning studies should use the same pozzolans and
the water source is a stream or another body of
cements that will be used on the project and must
water of unknown quality. Seawater has been used
successfully as mixing water, but this should only
determine that the final concrete characteristics,
be done if there is no feasible alternative. There may
strength gain, and durability are adequate.
be up to a 15 percent loss in ultimate strength, set
8. Miscellaneous materials.
times may be affected, and surface efflorescence
a. Other materials used in concrete pavement
may occur. The risk of steel corrosion maybe increased,
construction including curing materials, dowels, tie
so the use of coated dowels and reinforcing steel
should be considered if seawater is to be used.
bars, reinforcement, and expansion-joint filler are
covered by applicable specifications. When concrete
is required to be free of magnetic materials, special
10. Sampling and testing of materials.
instructions will be obtained from HQDA (DAEN-
a. Cement. Cement to be used in pavements for
ECE-G) for the selection of dowels, tie bars, and
aircraft traffic will be sampled and tested. Cement
reinforcement. Aluminum will not be used in concrete
meeting all other test requirements may be accepted
prior to the required 7-day age when the strength is
pavements.
b. Field welding of crossing bars (tack welding) is
equal to or greater than the 7-day strength require-
prohibited. All welded splices will conform to the
ment. Cement for pavement projects requiring 1,600
requirements of the American Welding Society (AWS)
cubic yards or less of concrete may be accepted on
D 1.4. Selection of the proper welding procedure
the basis of the manufacturer's certified mill test
reports showing compliance with cited cement
depends on the actual chemical composition of the
steel. A procedure suitable for one chemical compo-
specifications.
sition can be totally unsuited for another composition
b. Aggregates.
of the same strength grade. It is essential that the
(l.) Listed sources. Listing of aggregate sources
composition of the steel to be welded be determined
will be based on a thorough investigation to determine
before the welding procedure is established. Where
that suitable aggregates are obtainable for the
reinforcing bars are to be ordered for new work, the
proposed use. Evaluation of the material will require
fabricator should be informed that welded splices
complete laboratory testing including petrographic
are contemplated. The fabricator can provide the
examinations, physical tests, durability tests, and
chemical composition of the reinforcing bars and in
alkali-reactivity tests. The service record of aggre-
many cases can provide bars that are more suited to
gates will be determined by inspecting structures
welding.
that have had exposure equivalent to the proposed
c. Epoxy-coated reinforcing steel and dowel bars
structure. When an aggregate source has been listed
are being used more frequently in areas such as
previously for use on the basis of a complete investi-
bridge decks, coastal areas, and pavements subject
gation, additional similar use of the source within a
to heavy applications of de-icing salts to minimize
period of 3 years may be permitted on the basis of
potential corrosion problems. If these materials are
petrographic examinations and limited physical
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