30 June 2001
h. Special Joint. A "special joint", as shown in Figure 12-32 (Sheet 3 of 3), can be used to provide
load transfer on the existing side of a new PCC to old PCC joint. This can be used under the conditions
listed below. Although somewhat expensive, this is an excellent joint when constructed properly, but
requires close supervision in the field to ensure that the constructor builds it properly. Note that
considerable handwork is required in grading the undercut and placing concrete and reinforcement.
(Never should the contractor be allowed to attempt to fill the undercut with concrete spread by the
paver.) Special joint (undercut) between new and existing pavements. A special joint (undercut)
(Figure 12-32 (Sheet 2 of 3)) may be used at the juncture of new and existing pavements for the
(1) When load-transfer devices (keyways or dowels) or a thickened edge was not provided at
the free edge of the existing pavement.
(2) When load-transfer devices or a thickened edge was provided at the free edge of the
existing pavement, but neither met the design requirements for the new pavement.
(3) For any joints, when removing and replacing slabs in an existing pavement if the existing
load-transfer devices are damaged during the pavement removal, and if other types of joints are
The special joint design need not be required if a new pavement joins an existing pavement that is
grossly inadequate to carry the design load of the new pavement or if the existing pavement is in poor
structural condition. If the existing pavement can only carry a load that is 50 percent or less of the new
pavement design load, special efforts to provide edge support for the existing pavement may be omitted.
However, if the provisions for edge support are omitted, accelerated failures in the existing pavement
may be experienced. Any load-transfer devices in the existing pavement should be used at the juncture
to provide as much support as possible to the existing pavement. The new pavement will simply be
designed with a thickened edge at the juncture. Drilling and grouting dowels in the existing pavement for
edge support may be considered, if structurally suitable, as an alternative to the special joint, but a
thickened-edge design will be used for the new pavement at the juncture.
i. Tied Joints (Navy Only). Tied joints are seldom used for airfield pavement. However, two
(1) As required and shown in Figure 12-29, "Typical Jointing". (The situation must be evaluated
and existing service experience observed to prevent tying two slabs that have conditions (dimensions or
aggregate properties) which may cause a crack to form between the tied joint and the next adjacent
(2) Where half a slab is removed across a paving lane halfway between transverse joints (at
least 3 meters (10 feet) must be removed and not less than 3 meters (10 feet) remain). In this instance,
the new construction joint of new to existing, at mid-slab, must be tied (with drilled and epoxied
reinforcing bars). No joint reservoir should be sawed, or sealant applied.
j. Portland Cement Concrete to Asphalt Concrete Intersections. Figures 12-35, 12-36, 12-37, and
12-38 show various types of joints to use for the juncture of PCC and AC pavements.
(1) Figure 12-35. This joint is to be used for most transverse joints that will receive aircraft
traffic at Army installations and for all transverse joints that will receive aircraft traffic at Air Force