TM 5-809-1/AFM 88-3, Chap. 15
(2) Dowel placements. Normally, dowels
operations. For proper drainage of the floor-slab
surface into floor drains, a fall of c inch per foot
should be located at the middepth of the floor slab.
However, a tolerance of one-half of the dowel
toward the floor drain is recommended. For
diameter, above or below middepth of the slab, may
sustained operations, gasoline- and LP gas-operated
be allowed in locating the dowels in contraction and
forklift trucks can generally negotiate a maximum
construction joints where the allowance of such a
slope of 20 percent (20 feet vertically for every 100
tolerance will expedite construction.
feet horizontally) satisfactorily. Electric-powered
f. Joint sealing. All joints will be sealed with a
forklift trucks can perform sustained operations on
suitable sealant to prevent infiltration of surface
a maximum slope of 10 percent (10 feet vertically
water and solid substances. A jet-fuel resistant
for every 100 feet horizontally). The above-
(JFR) sealant will be used in the joints of floors
mentioned maximum slopes are based on a
where diesel fuel or other lubricants may be spilled
coefficient of friction of 0.9 for the operating
during the operation, parking, maintenance, and
surface. The use of sealants, waxes, etc., to reduce
servicing of vehicles. Sealants that are not fuel
dusting will lower the coefficient of friction
resistant will be used in joints of all other
considerably. In areas where these compounds are
pavements. JFR sealants will conform to Federal
used and a tough broom finish is not. practical,
Specifications SS-S-200 and SS-S-1614, and non-
reducing the slope of the ramp should be
JFR sealants will conform to Federal Specifications
considered. If the slope cannot be reduced,
55-5-1401. Preformed seal-ants must have an
pressure-sensitive abrasive tapes should be installed.
uncompressed width of not less than twice the width
The abrasive tapes are of the type used on stairway
of the joint sealant reservoir. The selection of a
treads to produce a nonskid surface.
pourable or preformed sealant should be based upon
5-9. Fiber reinforced design.
the economics involved. Compression-type
a. Basis of jointed fiber reinforced concrete floor
preformed sealants are recommended when the joint
slab design. The design of jointed fiber concrete
spacings exceed 25 feet and are required when joint
(JFC) floor slabs is based upon limiting the ratio of
spacings exceed 50 feet.
the concrete flexural strength and the maximum
g. Special provisions for slipform paving. Provi-
tensile stress at the joint, with the load either parallel
sions must be made for slipform payers when there
or normal to the edge of the slab, to a value found
is a change in longitudinal joint configuration. The
to give satisfactory performance in full-scale
thickness may be varied without stopping the paving
accelerated test tracks. Because of the increased
train, but the joint configuration cannot be varied
flexural strength and tenacity at cracks that develop
without modifying the side forms, which will nor-
in the fibrous concrete, the thickness can be
mally require stopping the paver and installing a
significantly reduced; however, this results in a more
header. The following requirements shall apply:
flexible structure, which causes an increase in
(1) The header may be set on either side of
vertical deflections as well as in potential for den-
the transition slab with the transverse construction
sification and/or shear failures in the foundations,
joint doweled as required. The dowel size and
pumping of the subgrade material, and joint
location in the transverse construction joint should
deterioration. To protect against these latter factors,
be commensurate with the thickness of the
a limiting vertical deflection criterion has been
pavement at the header.
applied to the thickness developed from the tensile
(2) When there is a transition between a
stress criteria.
doweled longitudinal construction joint and a keyed
b. Uses. Although several types of fiber have been
longitudinal construction joint, the longitudinal con-
studied for concrete reinforcement, most of the
struction joint in the transition slab may be either
experience has been with steel fibers, and the design
keyed or doweled. The size and location of the
criteria presented herein are limited to steel fibrous
dowels or keys in the transition slabs should be the
concrete. Fibrous concrete is a relatively new mate-
same as those in the pavement with the doweled or
rial for pavement construction and lacks a long-time
keyed joint, respectively.
performance history. Because of this, its use will
(3) When there is a transition between two
require approval of HQDA (DAEN-ECE-G), Wash-
keyed joints with different dimensions, the size and
ington, DC 20314-1 000, and/or Headquarters, Air
location of the key in the transition slab should be
Force Engineering Services Center (DEMP),
based on the thickness of the thinner pavement.
Tyndall AFB, Fla. 32403. The major uses to date
have been for thin resurfacing or strengthening
5-8. Floor slab geometry.
overlays where grade problems restrict the thickness
Careful attention should be given to floor-slab
of overlay that can be used. The use of JFC floor
slabs should be based upon the economics involved.
5-25
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