TM 5-809-1/AFM 88-3, Chap. 15
(3) Spacing of transverse contraction joints.
dimensions under traffic. Therefore, it is desirable,
Transverse contraction joints will be constructed
insofar as practicable, to keep the length and width
across each paving lane perpendicular to the center
dimensions as nearly equal as possible. In no case
line. The joint spacing will be uniform throughout
should the length dimension (in the direction of
any major paved area, and each joint will be straight
paving) exceed the width dimension more than 25
and continuous from edge to edge of the paving lane
percent.
(a) Nonreinforced slabs. The joint spac-
and across all paving lanes for the full width of the
paved area. Staggering of joints in adjacent paving
ings in table 5-2 have given satisfactory control of
lanes can lead to sympathetic cracking and will not
transverse cracking in most instances and may be
be permitted unless reinforcement, as described in
used as a guide, subject to modification based on
paragraph 5-5b, is used. The maximum spacing of
available information regarding the performance of
transverse joints that will effectively control
existing pavements in the vicinity or unusual proper-
cracking will vary appreciably depending on
ties of the concrete. The maximum size of a slab
pavement thickness, thermal coefficient, and other
panel bounded by contraction joints should be 600
characteristics of the aggregate and concrete,
square feet in accordance with TM 5-809-2/AFM
climatic conditions, and foundation restraint. It is
88-3, Chap. 2. Under certain climatic conditions,
impracticable to establish limits on joint spacing that
joint spacings different from those in table 5-2 may
are suitable for all conditions without making them
be satisfactory. Where it is desired to change the
unduly restrictive. For best slab performance, the
joint spacing, a request will be submitted to HQDA
number of joints should be kept to a minimum by
(DAEN-ECE-G), Washington, DC 20314-1000, or
using the greatest joint spacing that will
Headquarters, Air Force Engineering Services
satisfactorily control cracking. Experience has
Center (DEMP), Tyndall, AFB, Fla. 32403,
shown, however, that oblong slabs, especially in thin
outlining the local conditions that indicate that the
slabs, tend to crack into smaller slabs of nearly equal
proposed change in joint spacing is desirable.
Table 5-2. Recommended Spacing of Transverse Contraction Joints
Slab Thickness
Joint Spacing
in.
ft.
4 - 6*
Up to 12.5
6-9
12.5-15.0
9 - 12
15.0-20.0
> 12
20.0 - 25.0
*This thickness is allowed for steel-fiber reinforced concrete only.
5-15
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