30 June 2001
line of the three shows a good jointing pattern with nine lanes at 6.0 meters (20 feet) and two fill-in lanes
at 6.36 meters (20.9 feet)--well within criteria for shape. The bottom one of the three is also a good
jointing pattern with five pioneer lanes at 6.0 meters (20 feet) and four fill-in lanes at 6.18 meters
(20.3 feet). Neither of these two last systems requires the contractor to adjust his paver to anything
other than an even width or to make any changes in adjustment.
(4) Figure 12-42. This is simply a further explanation of Figure 13-2b, with more details. See
also subparagraph 12g.
(a) This figure shows a new PCC pavement intersecting an existing PCC pavement at an
angle (90 degrees). Such an intersection requires a joint that can tolerate movement, both at right
angles to the joint and along the joint, as well as providing load transfer across the joint.
(b) One approach would be to drill and grout dowels in the existing PCC and put in a
doweled expansion joint at the intersection. This is not desirable, because it locks the two pavements
together and does not permit any translation movement along the joint. This is particularly significant if
the angle of intersection is other than 90 degrees.
(c) Another approach would be to put in a thickened-edge expansion joint at the
intersection. But often the existing pavement will not have a thickened edge--and thus no true load
transfer across the joint can take place.
(d) The usual approach is to provide joints as shown. A doweled construction joint is
installed at the intersection of the two pavements--dowels drilled and grouted into the existing PCC. This
provides load transfer but no chance for translation movement. Opportunity for movement is provided by
installing a thickened-edge expansion joint at a transverse joint in the new pavement. This should be
just far enough back to provide a straight joint from edge to edge of the pavement (primarily to get past
the end of the fillet). Note that transverse joints within the fillet area are not straight lines and would
prohibit any movement along the joint.
(e) Note that the existing joints and the joints in the new area between the intersection and
the expansion joint are at the same spacing. This prevents the need for any other action to prevent
sympathetic cracking from any mismatched joints at the intersection. (Not always is it feasible to line up
these joints, but an attempt to should be made.) At the expansion joint it is not necessary to line up joints
on both sides. This permits making an easy change from the existing joint spacing to a different spacing
in the new pavement.
(f) Also note that the 900-millimeter (3-foot) ends of joints intersecting curved fillets must be
angled to be perpendicular to the curve at their intersection.
(5) Figure 12-43. This figure illustrates what can happen when a good jointing pattern is
messed up by the joint sawing crew. This occurred on a big PCC apron at a military base. What
happened was that the crew sawing transverse contraction joints (at night of course) spaced the sawed
transverse joints as intended in about 85 percent of the longitudinal paving lanes, with 37 uniformly
spaced joints at the left end of the apron, and 3 lesser spaced joints at the right end. But, on the other
15 percent of the longitudinal lanes, they measured the transverse joints backward, with uniform spacing
at the right end and lesser spacing at the left end. Outside of the fact that there will be sympathetic
cracking at the mismatched joints, structurally the pavement is excellent with a good surface finish.
However, the appearance is shocking because of the mismatched lanes, and every commander that
sees it will ask "Who built this queer thing."