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More info about MudJacking -
also
refered to as - Concrete leveling
In
civil engineering, concrete leveling (mudjacking) is a procedure
that attempts to correct an uneven concrete surface by altering the
foundation that the surface sits upon. It is a less expensive
alternative to having the damaged concrete torn-out and replacement
concrete poured, and is commonly performed all around the world. In
1977, the term concrete leveling was coined by Randall Greene in
Cleveland, Ohio.He created the phrase to convey his company's ability
to both raise and lower concrete to correct the insufficient grade of
a slab.
Causes
of Concrete Sinking
or Settling
Concrete
slabs and driveways can be susceptible to settlement from an
extremly wide variety of factors. In many areas of the United States,
naturally occurring soils can consolidate over time, especially in
the areas of the mid-west United States specifically areas ranging
from Texas up through to Wisconsin. Soil erosion wash out also
contributes to concrete sinkholes and settlement, as this is very
common for locations with poor or improper drainage. Concrete
driveways or slabs built upon filled-in land can over excessively
settle as well. This is common for many homes with basement levels,
as the fill material or dirt on the outside of the foundation
frequently is not "compacted" properly or at all. In some
cases, the concrete slabs pitch down, directing water down towards
the basement level. Tree roots can actually heave a slab upwards;
this is quite common along public roadways, especially within
Metropolitan areas.
What
is Mudjacking
Mudjacking
is a specialty concrete repair technology. In essence, mud jacking
attempts to lift a sunken concrete driveway by pumping a grout
mixture through the concrete underside, effectively pushing it up
from below. The process is also commonly referred to as
"slabjacking" and "pressure grouting" as well.
Accounts
of raising large concrete slabs through the use of hydraulic
pressure date back to the early 1900's. Early contractors utilized a
mixture of locally available soils (sometimes including crushed
limestone and/or cement for strength), producing a
"mud-like" substance and thus the term
"mudjacking". Modern slabjacking contractors can now
utilize an expanding polyurethane foam, providing a multitude of
benefits when compared to traditional slabjacking materials.
The
slabjacking process generally starts with drilling small diameter
access holes in the slab, driveway or sidewalk that is strategically
located to maximize lift. These holes are generally 5/8"
diameter for urethane slabjacking and can be over 1" in diameter
for traditional mudjacking applications.
Initial
material injections will fill any underslab void space. Once the
void space is filled, subsequent injections will start lifting the
concrete within minutes. After the slabs are lifted, the access holes
are patched and the work is complete.
The
process is very rapid when compared to traditional "rip and
replace" applications and is minimally disturbing to the
surrounding areas.
Concrete
Leveling with Foam Injection
Foam
leveling utilizes two part closed cell polymer expanding foam
injected through a hole less than one inch in diameter, typically
5/8". Although the material is injected at a higher psi rate
than traditional cementious grouts, the pressure is not what causes
the lifting. The expansion of the injected material below the slab
surface performs the actual lifting action. Material injected below a
slab to be lifted will first find weak soils, expanding into them in
such a manner as to consolidate and cause sub-soils to become more
dense and fill any voids below the slab. One inherent property of
expanding foams is that they will follow the path of least
resistance, expanding in all directions. Another inherent property
includes reaching a hydro-insensitive or hydrophobic state when cured
with 100% cure times as little as 30 minutes. Closed cell polymer
foams offer benefits which go beyond the goal of leveling hard
surfaces. They will not retain moisture, which in northern climates
can cause frost heaving. They are not subject to erosion once in
place. Their fast cure time allows for immediate use when application
is complete. Their light weight, 3 to 8 lbs. per cubic ft. vs. 100 to
120 lbs. per cubic ft. for cementious grout will not cause further
settlement. Foams will retain their cured shape and volume
indefinitely reducing the possibility of new voids forming below
grade to nearly zero unless acted upon by some outside cause. Some
closed cell polymer foams have baseline lifting capabilities of 6,000
lbs per sq. ft. and leveling procedures have been performed in which
loads as high as 125 tons have been lifted and stabilized in a
surface area of less than 900 sq. ft.
