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Compaction Grouting
A soil correction
pressure system to increase the bearing capacity of
soils. The compaction application is accomplished by pumping
a thick cement grout, under intense pressure, into a
particularized location of ground to
compact its surrounding areas of soil. The expanding grout pushes the uncompacted soil to the
side as it forms a concrete column, sized as needed.
Sometimes this compaction method is also known
as pressure grouting.
Displacement of the soil is produced by the overburden
pressure pushing back against all sides of the compaction grout
column. A major advantage of using
compaction grouting is
that its top peak effect is realized in the weakest or
softest strata of the soils underlying a building.
The system uses include pre-construction preparation of
soils, lifting structure approaches, re-leveling roads,
bridges, towers, existing damaged structures, blocking flow-path of
viscous liquids through stratum layers, filling rock cracks
(microfine cement),
voids, and hairline fractures, construction of underpinning, densifying footing soils, and remediation of dangerous sinkholes.
This pressure grout technique is mostly used to increase
the substructure soil density.
Usually, grout (cement) is applied in measured stages
beginning at the lowest point of a drilled shaft then
working upward through the weak ground. On very shallow
injection applications,
compaction grout can be injected from
top down, building a cap. This method densifies the upper
portions of treated area first so that it becomes a dense
cap to help the containment of the expanding grout at lower
stratum levels.
When applied in a grid style layout, the pressure treated
soil underneath the foundation has a greater uniformity
throughout its entire mass, which gives maximum soil
stabilization that provides solid foundation support
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Foundation Lifting
Sequence
Provides foundation support consisting of pressure
filled
concrete piles,
used either as end bearing or skin friction bases for lifting or
stabilizing foundations.
1. The first step in compaction grout piles construction is coring
through existing footing extensions.
2. An iron casing is driven through the hole footer
protrusion hole down to bedrock or proper friction depth.
3. A thick, mortar-like cementitious mixture (grout), less than two
inch (2”) slump
having more than 3,000 psi compressive strength, is steadily pumped at
pressures up to 1,000 psi contained within the steel casing to form a
uniform cohesive concrete bulb.
4. The bulb is expanded to one-foot diameter by
displacement of soil at lower
tip of casing,
while a calculated and measured volume of compaction grout is steadily maintained.
5. The pressure grouting tube is raised one foot, and the
pressurized process repeated.
6. Pressure injections continue as casing is withdrawn
up to the structure's cement footing, which creates an in-place solidified
grout pile
surrounded by intensely compacted soil.
7. Threaded bar (75 ksi) is inserted into
compaction grouting opening and then sealed
over using a similar cement material.
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