FLAT
JACKS
Low
height steel capsule jacks
The Structural Engineer's Solution for
Temporary & Permanent Load Transfer
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Permanent Flat Jacks
Cementitious
grout or epoxy resin inflation
Where a force is required to be permanently applied to a structure, Flat
Jacks are inflated under pressure with grout or epoxy resin by means of
special purpose injection cylinder. The grout or epoxy resin hardens over
a period of time to leave the force permanently applied. This type of
application is suitable for pre-loading new or additional support steelwork
in structures, underpinning works and structural bearing installation.
Broadgate, UK
Cementitious grout is preferred over epoxy resin whenever possible mostly because it is more environmentally acceptable. However, in some cases such as complex synchronised inflation of multiple jacks, resin is the only suitable injection substance. This method is often used where sufficient room is not available for wedging or grouting the jacking gap.
In certain circumstances it may be necessary to carry out the initial inflation on oil or water with resin inflation being carried out at a later date. A grout or transfusion system is then required.
Transfusion
of oil or water to grout or epoxy resin
There are two basic methods of transfusion of Flat Jacks that are pressurised
with hydraulic oil or water:
Single
special transfusion Flat Jacks method
At individual jack locations single special transfusion jacks, which
are purpose designed and manufactured, can be transfused with grout
or resin under load. The pressure within the Flat Jack is balanced and
maintained throughout the process of transfusing.
Additional
Flat Jacks method
If adequate space is available two Flat Jacks may be installed one above
the other. The first is inflated with hydraulic fluid and adjusted as
necessary over a period of time until the required condition is achieved.
Then the second Flat Jack is inflated directly with grout or epoxy resin.
The pressures in both Flat Jacks are balanced throughout until the oil
or water Flat Jacks has closed and the inflation is completed on the
grout or resin Flat Jack. This will then harden and both jacks will
remain in position permanently.
Use
of cementitious grout or epoxy resin
The most common epoxy resin used in Flat Jack inflation is a two part
pouring grade mixture to which an accelerator is added in varying amounts
to produce a setting time suitable for the location, ambient conditions
and application.
The mixing and pumping of grout or epoxy resins requires considerable skill and experience. Incomplete mixing with hardener may result in failure to set. Excessive accelerator may cause premature setting which will cause blockage, frustrate the Flat Jacking operation and damage the pumping equipment.
For these reasons grout or resin injection equipment is not hired to third parties and Fagioli Limited contract service of injection is strongly recommended.