30 June 2001
6 millimeters (1/4 inch) in thickness when joints match or normal nonextruding-type material not less
than 6.3 millimeters (1/4 inch) in thickness when joints do not match. Where large expansions may have
a detrimental effect on adjoining structures, such as at the juncture of rigid and flexible pavements,
expansion joints in successive transverse joints back from the juncture should be considered. The
depth, length, and position of each expansion joint will be sufficient to form a complete and uniform
separation between the pavements and between the pavement and the structure concerned and, unless
doweled, must be completely straight from end to end so translation can occur. The designer should
dowel expansion joints only under special conditions. (Use thickened edge expansion joints.)
Expansion joint filler must cover the full depth of the joint surface so there is no point-to-point contact of
(2) Between pavement and structures. Expansion joints will be installed to surround, or to
separate from the pavement, any structures that project through, into, or against the pavements, such as
at the approaches to buildings or around drainage inlets and hydrant refueling outlets. The thickened-
edge-type expansion joint will normally be best suited for these places.
(3) Within pavements.
(a) Expansion joints within pavements must be carefully constructed. Except for protecting
abutting structures and taxiways intersecting at an angle, their use will be kept to the absolute minimum
necessary to prevent excessive stresses in the pavement from expansion of the concrete or to avoid
distortion of a pavement feature through the expansion or translation of an adjoining pavement. The
determination of the need for and spacing of expansion joints will be based upon pavement thickness,
thermal properties of the concrete, prevailing temperatures in the area, temperatures during the
construction period, and the experience with concrete pavements in the area.
(b) Longitudinal expansion joints within pavements will be of the thickened-edge type
(Figure 12-33). Dowels are not recommended in longitudinal or most transverse expansion joints
because differential expansion and contraction and subgrade movement parallel with the joints may
develop undesirable localized strains and possibly failure of the concrete, especially near the corners of
slabs at transverse joints.
(c) Transverse expansion joints within pavements will often be the doweled type
(Figure 12-33). There may be instances when it will be desirable to allow some slippage in the
transverse joints, such as at the angular intersection of pavements to prevent the expansion of one
pavement from distorting the other. In some of these instances, instead of a transverse expansion joint,
a thickened-edge slip joint may be used (Figure 12-34). When a thickened-edge joint (slip joint) is used
at a free edge not perpendicular to a paving lane, a doweled transverse expansion joint will be provided
as shown in Figure 12-32.
d. Dowels. The important functions of dowels or any other load-transfer device in concrete
pavements are to help maintain the alignment of adjoining slabs and to transmit loads across the joint.
Different sizes of dowels will be specified for different thicknesses of pavements (Table 12-8). When
extra-strength pipe is used for dowels, the pipe will be filled with either a stiff mixture of sand-asphalt or
portland cement mortar, or the ends of the pipe will be plugged. If the ends of the pipe are plugged, the
plug must fit inside the pipe and be cut off flush with the end of the pipe so that there will be no
protruding material to bond with the concrete and prevent free movement of the dowel. Figures 12-30,
12-32, and 12-33 show the dowel placement. All dowels will be straight, smooth, and free from burrs at
the ends. One end of the dowel will be painted and oiled to prevent bonding with the concrete. Dowels