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Cracks in Masonry
- To: "Seaint(--nospam--at)Seaint.Org" <seaint(--nospam--at)seaint.org>
- Subject: Cracks in Masonry
- From: "M. David Finley, P.E., P.A." <davidfinley(--nospam--at)bizsea.rr.com>
- Date: Fri, 12 Jan 2007 16:45:15 -0500
bridge consisting of single web precast t-beam. 60'-0" span.
Abutments are rectangular (8'-0" wide to match the t-beam and 6'-0" long).
The front (bridge side) wall bears on a concrete gravity wall.
The side walls bear partly on the gravity wall and partly on a
continuous strip footing. The rear wall is on a strip footing. All
of the masonry is 8"x8"x16 CMU with no vertical or horizontal reinforcing
and no grouted cells.
The masonry in the
abutments has cracks, including some with in/out of plane
displacement. The cracks appear to be caused by the fact that the
original construction apparently ignored thermal effects and "locked" both
ends of the single web t-beam into the front masonry wall.
I am correcting the
expansion issue by providing expansion joints at each end of the
bridge. No problem there. And the new expansion joints will
significantly reduce the forces being transferred into the
The Owner (small
town, so limited funds) wants to repair the masonry by patching the
cracks with mortar. Some of the cracks are 3/4" wide. Can cracks
that wide be adequately repaired with mortar? Or should some type of
pressure epoxy grouting be used?
Of course this
bridge has historical significance, so the "tear down and replace" option is not
M. David Finley, P.E., P.A.
SW Main Boulevard - Suite 111
Lake City, FL 32025