Figure 7-15.Piles pulled by heaving deck.
properly to eliminate reflection cracking and
subsequent premature failure of the new asphalt
surface cover. Liquid asphalt is applied to the surface
of the portland cement surface as a primer, and a dense
graded mix of asphalt concrete or sheet asphalt is laid
as a surface according to a predetermined design. A
partial remedy to protect concrete from chemical
deterioration is to apply a layer of dense impervious
concrete properly anchored to the old work or some of
the newer materials, such as epoxy resin formulations.
Free standing components of structures damaged
or deteriorated by such means as spalling or
longitudinal or horizontal cracks in tiles and bracing
can be repaired above the waterline. Pressure-applied
mortar, epoxy formulations, normal portland cement
concrete, or grout are the materials used. Encasement
of damaged portions in reinforced concrete is the
conventional method of repairing piling. It is always
preferable to place concrete in air if economical and
feasible; however, this requires the use of cofferdams,
and it is not always an economical solution. When the
solution dictates, concrete can be placed under water.
Forms may be used, as shown in figures 7-16 and 7-17.
Figure 7-16.Encasement of damaged piles (wood form).
Additional reinforcing in the form of rods or mesh is
placed around the damaged pile, and sectional forms
are used to hold the concrete in place until it cures.
Forms may be made of pipe, sheet metal, or wood and
are split in half vertically so that they can be placed
around the tile and bolted together above the water.
Each section is then slid into place and new sections
added until the desired length is obtained. The form is
then filled with concrete. Forms may be left in place
or removed for reuse. Where only a section of the pile
is to be encased in concrete and the forms do not extend
to the mud line, the lowest section of the forms must
be closed to hold the concrete or aggregate and grout
in place. (See fig. 7-17.) Pressure-applied concrete
may be used to make sectional forms. These are built
upon cylinders of expanded metal laths shaped to fit
around the pile. Wire mesh reinforcement may be used
outside of the metal lath where additional strength is
required. Pressure-applied concrete is used to make a
sectional form 1 or 2 inches thick, and the concrete is
allowed to set. This form is then dropped into place
and filled with concrete.