UFC 3-260-02
30 June 2001
c. Mismatched Joints. Steel reinforcement in the slabs is mandatory to prevent migration of cracks
into adjacent pavements for the following two conditions of mismatched joints:
(1) Where joint patterns of abutting pavement facilities do not match, partial reinforcement of
slabs may be necessary. In such a condition, the mismatch of joints can cause a crack to form in the
adjacent pavement unless there is sufficient width of bond-breaking medium installed in the joint. The
determination relative to using reinforcement at mismatched joints in such junctures is based upon the
type of joint between the two pavement sections. A partial reinforcement of the slab, as described
below, is required when the joint between the abutting pavement is one of the following: (a) doweled
construction joint, (b) keyed construction joint, (c) thickened-edge butt joint without a bond-breaking
medium, (d) doweled expansion joint, and (e) thickened-edge slip joint with less than 6.4-millimeter
(1/4-inch) bond-breaking medium. Reinforcement is not required if the joint between the abutting
pavement facilities is either a thickened-edge expansion joint or a thickened-edge slip joint with
6.4 millimeters (1/4 inch) or more of bond-breaking medium, except for a mismatch of joints in the center
23-meter (75-foot) width of runway where reinforcement of the slabs of mismatched joints will be
required regardless of the type of joint between the facilities. When reinforcement at mismatched joints
is required, the slab in the pavement facility directly opposite the mismatched joint will be reinforced with
the minimum 0.05 percent steel. The reinforcing steel will be placed in two rectangular directions for a
distance 915 millimeters (3 feet) back from the juncture and for the full width or length of the slab in a
direction normal to the mismatched joint. When a new pavement is being constructed abutting an
existing pavement, the new slabs opposite mismatched joints will be reinforced in the manner described
above. When two abutting facilities are being constructed concurrently, the slabs on both sides of the
juncture opposite mismatched joints will be reinforced in the manner described above. For this condition
shown in Figure 13-2, the slip joint bond-breaking medium can be specified to be a full 6.4 millimeters
(1/4 inch) thick, and the reinforcing may be omitted.
(2) The second condition of mismatched joints where reinforcement is required occurs in the
construction of a plain concrete overlay on an existing rigid pavement. Joints in the overlay should
coincide with joints in the base pavement. Sometimes this is impracticable due to an unusual jointing
pattern in the existing pavement. When necessary to mismatch the joints in the overlay and the existing
pavement, the overlay pavement will be reinforced with the minimum 0.05 percent steel. The steel will
be placed in two rectangular directions for a distance of at least 915 millimeters (3 feet) on each side of
the mismatched joint in the existing pavement. The steel will, however, not be carried through any joint
in the overlay except as permitted or required to meet joint requirements. If the joint pattern in the
existing pavement is highly irregular or runs at an angle to the desired pattern in the overlay, the entire
overlay will be reinforced in both the longitudinal and transverse directions. When a bond-breaker
course (see Chapter 17) is placed between the existing pavement and overlay, reinforcement of the
overlay over mismatched joints is not required, except for mismatched expansion joints.
d. Reinforcement of Pavements Incorporating Heating Pipes. Plain concrete pavements, such as
hangar floors that incorporate radiant heating systems within the concrete, are subject to extreme
temperature changes. These temperature changes cause thermal gradients in the concrete that result in
stresses of sufficient magnitude to cause surface cracking. To control such cracking, these pavement
slabs will be reinforced with the minimum 0.05 percent steel placed in the transverse and longitudinal
directions.
e. Reinforcement of Slabs Containing Utility Blockouts. The minimum 0.05 percent steel
reinforcement is required in plain concrete pavement slabs containing utility blockouts, such as for
hydrant refueling outlets, storm drain inlets, and certain types of flush lighting fixtures. The entire slab or
slabs containing the blockouts will be reinforced in two rectangular directions.
13-4
Previous Page
