7
being more effective than resin as it also has a neutralizing
effect for acids. However, using resin instead of grout offers
several advantages when pumping bolts. Resin from the
factory is checked for quality control and provides a con-
sistent product in both strength and viscosity when prop-
erly mixed with the proper hardener. Grout is mixed on the
machine and the operator must be careful to add water at
the proper ratio or strength will be greatly reduced and the
grout will lose viscosity and run out of up holes.
Another potential option is the selection of support
material as utilizing a fiberglass bolt or fiber mesh which
will not corrode as no metal is involved. Bolts that do
not react(nonmetal) and fiberglass reinforced rock bolts
are more effective versus double coated steel bolts (Clarke
and Sieders, 2014). Fiberglass bolts have as only 25%
shear resistance of metal bolts and a much lower torsional
strength (120–230NM versus 1160NM for steel bolt), but
more shear resistance than inflatable bolts (Swellex).
The best mitigation in a practical sense is to limit the
exposure of the steel to the either carbonic or sulpheric acid
as corrosion agents. Other more expensive and complicated
options are to coat the individual bolts and mesh with a
coating to stop the anodic destruction from electrolysis,
such as from galvanization or coatings of zinc, aluminum,
or magnesium. Currently we have been using galvanized
bolts including cables to minimize corrosion. Galvanization
may not be good alternative for any elements when pH
goes below 4.
The least corrosion resistant ground support elements
such as black steel may only last 10 years, but important
infrastructure such as shafts and major haulage, develop-
ment, may have to last 30–50 years or more depending on
production. Goal should be to minimize potential shut-
down due to rehab from bolting or shotcrete.
Corrosion Mapping Classification
The current practice in the GCMP (Ground Control
Management Plan) has been to standardize elements based
on Hadjigeorgiou and Dorian, 2013 for Corrosion Level
damage (see Table 5). The guide is used as a guideline to
establish corrosion levels rates and the required maintenance
until corrosion is calibrated to the site. It is to be done on a
biannual basis, as part of the regular inspections including
damage mapping. Extra bolts will be installed for pull test-
ing to failure, as it may be the only way to determine if rock
support is compromised by corrosion or damage.
Water Sampling Requirements
Where water is encountered in sufficient quality, we need
to collect the following for testing: ph, TDSor total dis-
solved solids (sometimes measured as conductivity), DO
(dissolved oxygen), and temperature. These measurements
Figure 12. Relative corrosion resistance versus elongation
capacity for corrosion protection measures. From Preston
and others, (2019). Note: Installation in fully grouted anulus
offers best corrosion protection next to any additional
combinational coatings
Table 5. Corrosion Damage mapping scale based on
Hadjigeorgiou and Dorian, 2013
being more effective than resin as it also has a neutralizing
effect for acids. However, using resin instead of grout offers
several advantages when pumping bolts. Resin from the
factory is checked for quality control and provides a con-
sistent product in both strength and viscosity when prop-
erly mixed with the proper hardener. Grout is mixed on the
machine and the operator must be careful to add water at
the proper ratio or strength will be greatly reduced and the
grout will lose viscosity and run out of up holes.
Another potential option is the selection of support
material as utilizing a fiberglass bolt or fiber mesh which
will not corrode as no metal is involved. Bolts that do
not react(nonmetal) and fiberglass reinforced rock bolts
are more effective versus double coated steel bolts (Clarke
and Sieders, 2014). Fiberglass bolts have as only 25%
shear resistance of metal bolts and a much lower torsional
strength (120–230NM versus 1160NM for steel bolt), but
more shear resistance than inflatable bolts (Swellex).
The best mitigation in a practical sense is to limit the
exposure of the steel to the either carbonic or sulpheric acid
as corrosion agents. Other more expensive and complicated
options are to coat the individual bolts and mesh with a
coating to stop the anodic destruction from electrolysis,
such as from galvanization or coatings of zinc, aluminum,
or magnesium. Currently we have been using galvanized
bolts including cables to minimize corrosion. Galvanization
may not be good alternative for any elements when pH
goes below 4.
The least corrosion resistant ground support elements
such as black steel may only last 10 years, but important
infrastructure such as shafts and major haulage, develop-
ment, may have to last 30–50 years or more depending on
production. Goal should be to minimize potential shut-
down due to rehab from bolting or shotcrete.
Corrosion Mapping Classification
The current practice in the GCMP (Ground Control
Management Plan) has been to standardize elements based
on Hadjigeorgiou and Dorian, 2013 for Corrosion Level
damage (see Table 5). The guide is used as a guideline to
establish corrosion levels rates and the required maintenance
until corrosion is calibrated to the site. It is to be done on a
biannual basis, as part of the regular inspections including
damage mapping. Extra bolts will be installed for pull test-
ing to failure, as it may be the only way to determine if rock
support is compromised by corrosion or damage.
Water Sampling Requirements
Where water is encountered in sufficient quality, we need
to collect the following for testing: ph, TDSor total dis-
solved solids (sometimes measured as conductivity), DO
(dissolved oxygen), and temperature. These measurements
Figure 12. Relative corrosion resistance versus elongation
capacity for corrosion protection measures. From Preston
and others, (2019). Note: Installation in fully grouted anulus
offers best corrosion protection next to any additional
combinational coatings
Table 5. Corrosion Damage mapping scale based on
Hadjigeorgiou and Dorian, 2013