RAISING
SETTLED SLABS, WALKS:
A "settled" walk or slab is a common problem. It can be caused by
the concrete being placed over "soft" fill materials. In most cases,
you can re-level the slab or walk without breaking it out and
making a new concrete placement-unless it is too large to handle.
Raising
walks-
Using a walk as an example: the walk will have cracked at the
control groove cut in its top surface. If it hasn't, use a brick
chisel and baby sledge hammer to crack it along that area. This
will provide you with smaller work sections.
It's
easier-
Put a straight-edged 2X4 alongside the walk as a guide to indicate
where you want the top surface of the walk to be. Level the 2X4
as needed to suit the terrain. Then use a steel pry bar and fulcrum,
one on each side, to tilt and lift the lowest end of the slab up.
Prop
up the slab with a piece of 2X4 or rock. Since this is all hard
work, you may need a helper.
Measure
the height to which the slab should be brought. Make sure it is
propped up a little higher than the finished height will be. Place
stones and/or bricks under the slab to support it at the correct
height. Then place pea size gravel around the stones/bricks for
extra support.
If there
are roots in the area, cut as much of them away as possible. They
will continue to grow and tilt the slab out of level if you don't
do this.
Very
gently, and with help, lower the slab into place. Do the rest of
the walk one section at a time, until the walk matches the surrounding
terrain.
Gridded
patios-
Slabs in a gridded patio are reestablished the same way as walks,
using a steel bar and fulcrum to raise them. Use a steel bar or
pipe to hold them up out of the way until you prepare the ground
underneath for the slabs.
One-piece
slabs-
A large, badly settled, one-piece slab that doesn't have control
joints usually will have to be broken and replaced with a new slab.
You can place a new slab on top, after first roughening the surface
of the existing slab.
REPLACING
WALK SECTIONS:
If an entire section of a walk has broken so it can't be repaired
properly, use a brick chisel and baby sledge hammer at the control
joint to break it away from the solid part. Then, using a regular
sledge hammer, break the concrete into small sections for removal.
If you can, try to elevate the slab slightly off the ground. It
is easier to break with a sledge hammer this way.
Remove
all larger pieces of broken concrete and leave the smaller pieces
in the bottom of the area for fill stones. Make sure the new sidewalk
will be as thick as the existing sidewalk it will join.
Forms-
If you can't use the edges of the old concrete to support the new
mixture, build a form using 2X6s. Align the forms so the top edges
match the surface of the adjoining concrete. You probably will have
to dig a small trench along the sides of the patch area in which
to insert the forms.
Since
the new concrete forms a "patch," you probably won't need expansion
or control joints between the old and new concrete. However, if
control joints are necessary, make them by slicing through the fresh
concrete with the edge of a trowel at the point where the new concrete
meets the old. Or use asphalt expansion strips between sections.
This product is available at home center, building material, and
some hardware stores that stock building materials
Keep
the concrete damp with water spray for at least 3 days after it
has been placed. You can walk on the patch in about 40 hours; don't
drive a car or truck over the surface for at least 3 weeks. Forms
can be removed after 2 weeks; replace any dirt and sod you removed
to make way for the form boards.
