2
nozzlemen may deliver inconsistent application quality,
potentially compromising the structural integrity of
underground systems. Furthermore, fractures can
develop due to shear localization within the rock mass,
often occurring in areas with high stress concentrations and
minimal support (Wibisono et al., 2024). At least three
crucial factors are needed to say that the applied shotcrete
has good quality, such as continuity (Figure 2a), no spray
shadow behind the wire mesh (Figure 2b), and less rebound
(Figure 2c). The last factor will be evaluated and become
one parameter to be assessed in this study. The amount
of rebound is dependent on four major factors (Melbye,
1996): (i) nozzle angle to the substrate, (ii) accelerator dos-
age, (iii) nozzle distance to rock, and (iv) area of application
in the tunnel.
Comprehensive in-house training programs and
field support systems have been initiated to address these
demands and enhance nozzlemen proficiency. These initia-
tives combine practical skills-building, theoretical training,
and real-time feedback to ensure consistent and high-qual-
ity application. Advantages include alignment with avail-
able materials and equipment and continuous performance
monitoring for iterative improvements. This paper exam-
ines nozzleman assessment parameters, presents quality
evaluation results such as direct rebound measurements,
and offers actionable insights for optimizing shotcrete appli-
cation as a cornerstone of underground support systems.
METHODOLOGY
Preliminary observations were conducted to inform
the development of a comprehensive training program.
Reflecting the adage, “You can’t really know where you’re
going until you know where you have been,” these obser-
vations provided a foundational understanding of current
practices and gaps. Some detailed preliminary notes include
an early strength penetrometer test, field observations (area
preparation, safety, equipment, and spraying technique),
and a direct interview with the operator. The base training
module was designed to align with EFNARC (European
Federation of Nozzlemen and Apprentice Concrete
Sprayers) nozzleman certification scheme standards, ensur-
ing compliance with industry benchmarks (Lehto et al.,
2011). While the certification process verifies that indi-
viduals possess the necessary knowledge and skills to per-
form their roles effectively, it does not inherently address
specific improvement needs within the workforce. The final
module was customized based on observation outcomes
to bridge this gap, prioritizing critical improvement areas
before addressing further secondary aspects.
Figure 1. Annual shotcrete consumption driven by daily ore throughput in underground
mining operations worldwide (After Erismann et al., 2018). Labels indicate block or sublevel
caves currently in operation, under construction, or in the planning phase
nozzlemen may deliver inconsistent application quality,
potentially compromising the structural integrity of
underground systems. Furthermore, fractures can
develop due to shear localization within the rock mass,
often occurring in areas with high stress concentrations and
minimal support (Wibisono et al., 2024). At least three
crucial factors are needed to say that the applied shotcrete
has good quality, such as continuity (Figure 2a), no spray
shadow behind the wire mesh (Figure 2b), and less rebound
(Figure 2c). The last factor will be evaluated and become
one parameter to be assessed in this study. The amount
of rebound is dependent on four major factors (Melbye,
1996): (i) nozzle angle to the substrate, (ii) accelerator dos-
age, (iii) nozzle distance to rock, and (iv) area of application
in the tunnel.
Comprehensive in-house training programs and
field support systems have been initiated to address these
demands and enhance nozzlemen proficiency. These initia-
tives combine practical skills-building, theoretical training,
and real-time feedback to ensure consistent and high-qual-
ity application. Advantages include alignment with avail-
able materials and equipment and continuous performance
monitoring for iterative improvements. This paper exam-
ines nozzleman assessment parameters, presents quality
evaluation results such as direct rebound measurements,
and offers actionable insights for optimizing shotcrete appli-
cation as a cornerstone of underground support systems.
METHODOLOGY
Preliminary observations were conducted to inform
the development of a comprehensive training program.
Reflecting the adage, “You can’t really know where you’re
going until you know where you have been,” these obser-
vations provided a foundational understanding of current
practices and gaps. Some detailed preliminary notes include
an early strength penetrometer test, field observations (area
preparation, safety, equipment, and spraying technique),
and a direct interview with the operator. The base training
module was designed to align with EFNARC (European
Federation of Nozzlemen and Apprentice Concrete
Sprayers) nozzleman certification scheme standards, ensur-
ing compliance with industry benchmarks (Lehto et al.,
2011). While the certification process verifies that indi-
viduals possess the necessary knowledge and skills to per-
form their roles effectively, it does not inherently address
specific improvement needs within the workforce. The final
module was customized based on observation outcomes
to bridge this gap, prioritizing critical improvement areas
before addressing further secondary aspects.
Figure 1. Annual shotcrete consumption driven by daily ore throughput in underground
mining operations worldwide (After Erismann et al., 2018). Labels indicate block or sublevel
caves currently in operation, under construction, or in the planning phase