| It
often becomes difficult to decide whether crack injection
will be ideal or the other normal procedure in which concrete
is cut and repaired with cement sand epoxy mortar.
One way of answering this question is given here. Where
the concrete is of good quality, and there has been little
or no corrosion of reinforcement, so the only real defect
is presence of cracks, then crack injection will be considered
most suitable for the job.
If rusting and spalling have occurred, then follow the
complete repair steps given in the other section.
Grouting is a unique method to inject low viscosity epoxy
resin system into cracks in concrete structures, under air
pressure not exceeding 2-3 Kgs/cm2.
An injection grouting gun is used for this process to fill
up cracks and hollow areas in the concrete.
Procedure for Grouting:
• Widen the crack or joint wherever the injection work is
to be carried out (approximately 15 mm wide x 15 mm depth)
• Drill holes of about 13 mm dia upto 150 mm deep at 500
mm @ c/c.
• Use compressed air to clean the hole, as well as crack
to remove dust, dirt, loose materials etc.
• Use 12 mm dia specially threaded injection nipples and
fix them into the holes provided. Seal the entire surface
around the nipple with IPN Putty.
• Seal the surface of the crack with IPN Putty so as to
ensure that the injected grout does not leak from the gaps
& from cracked surface.
• The surface now is ready for injection.
• Prepare the injection grout and load it into the injection
gun.
Grouting Techniques
• Epoxy Injection Grouting : Cracks as
narrow as 1 mm can be bonded by the injection of epoxy.
The technique generally consists of establishing entry and
venting ports at close intervals along the cracks, sealing
the cracks on exposed surfaces and injecting the epoxy under
pressure. This technique is successfully used in repair
of cracks in buildings, bridges, dams and other types of
concrete structures.
• Cement Grouting : Wide cracks, particularly
in gravity dams and thick concrete walls, may be repaired
by filling with Portland cement grout. This may be effective
in stopping water leaks, but will not structurally bond
cracked sections. Suitable additives such as silica fume,
superplasticizers, copolymers etc. would help in better
performance of such grouts.
Fixing up of nozzles
Use of Grouting Gun for Epoxy Injection |
