15 March 2001
proper length for the welding procedure chosen and should be lapped at the center of the repair
area to avoid the potential buckling of bars on hot days (Figure 4.15.).
4.9. Expansion Joints. Expansion joints are placed in concrete pavements to provide relief for
expansion due to temperature changes. Generally, expansion joints are installed at all inter-
sections of pavements with structures and may be required within pavement features. Expansion
joints may be required if full-depth repairs are made during cool weather when adjacent concrete
is in a contracted state, or crushing and spalling of concrete at the joints may occur during subse-
quent hot weather when the concrete expands. Expansion joints in pavements should be kept to
the minimum necessary to prevent excessive stresses in the pavement. The types of expansion
joints are the thickened-edge (Figure 4.16.), the thickened-edge expansion joint (Figure 4.17.),
and the doweled type (Figure 4.18.).
4.9.1. The thickened-edge type is suggested for longitudinal expansion joints within pavements.
Dowels are not recommended for use in longitudinal expansion joints, because differential
expansion and contraction parallel with the joints may develop undesirable localized strains and
possibly failure of the concrete, expecially near the corners of slabs at transverse joints.
4.9.2. The thickened-edge expansion joint (without dowels) is normally the best suited expansion
joint to surround or separate any structure that projects through, into, or against the pavement
(apporaches to buildings, drainage inlets, and hydrant refueling outlets).
4.9.3. Doweled-type, transverse expansion joints should be used within pavements. However, at
the angular intersection of pavements, it might be desirable to allow some slippage in the trans-
verse joint to prevent the expansion of one pavement from distorting the other. In such instances,
the design of the transverse expansion joint should be a thickened-edge slip joint, or
thickened-edge expansion joint.