15 March 2001
10.1. Purpose. New pavement joints typically exhibit good load transfer, particularly if the joints
are doweled. However, repeated heavy loads can cause an elongation of the dowel sockets and
result in dowel looseness and a reduction of load-transfer efficiency. As load-transfer efficiency
decreases, many types of distress rapidly increase, including pumping, spalling, faulting, and slab
pavement by reducing the potential for the distress and the mechanisms previously described.
10.2. Need for Load-Transfer Restoration. Transverse joints or cracks that would benefit
improved load transfer can be identified by measuring the existing load-transfer efficiency with
heavy-weight, nondestructive, deflection testing devices such as the Falling Weight Deflectometer
(Figure 7.1.). These tests must be conducted during periods of cooler temperatures (less than
about 80 degrees Fahrenheit (27 degrees Celcius)) when the slab joints and cracks are not tightly
closed. Joints or cracks having a measured load-transfer efficiency (ratio of the deflection on the
unloaded side of a joint or crack divided by the deflection of the loaded side) of less than
50 percent should be considered for load-transfer restoration.
The deflection measurements should be taken as near as possible to the joint or crack. If a
sensor is used, the measurements should be taken in the center of the load plate and 12 inches
(300 millimeters) across the joint. The measurements taken in the center of the slab should be
corrected for normal slab bending.
10.3. Correction of Deficiencies. Before load-transfer devices are installed, it is necessary to
determine the cause of the joint or crack distress. Attempts should be made to correct these
deficiencies prior to load-transfer restoration. Heavy distressed slabs may require portions of or