wire mesh (which was eventually rendered unnecessary in many areas of the trial headings). Rock bolts (generally friction bolts or resin rebar bolts, per the mine’s ground control plan) were still installed for axial support, but with ICS these could be done after 2 hours the shotcrete had set enough to stabilize the area, or in some cases before blasting the next round rather than immediately in-cycle. This flexibility in sequencing was possible because the freshly sprayed shotcrete provided early reinforcement to hold the rock mass, reducing the urgency to install bolts at the exact same time. The spray rig and crew were trained to apply a uniform layer and to continuously monitor accelerator dosage and mix consistency. Quality control tests were conducted during the trial: fresh shotcrete slump, accelerator dosage rate, and early-age strength (using penetrometer and early-age cores) were measured periodically to ensure the target performance was being achieved in situ. 2.3 Safety and operational measures Implementing ICS requires careful coordination to maintain safety. Ventilation had to quickly clear blast fumes and dust so that shotcreting could commence sooner; auxiliary fans were used to speed up clearing the headings. Spraying shortly after blasting meant surfaces were still freshly fractured and, at times, marginally hotter and steamier (especially at 4,700 m elevation where boiling point is lower). Those conditions which were managed by ensuring sufficient cooling time (typically ~20–30 minutes after mucking) before spraying. Personnel safety was enhanced by using the robotic sprayer, allowing the operator to stand at a distance under supported ground. The fast set accelerator was alkali-free, greatly reducing the generation of caustic rebound dust compared to older alkaline accelerators (Allison et al., 2010), which improved the working environment. Reentry protocol was established such that once 2Mpa early strength was achieved (verified by predetermined time and occasional penetrometer tests), the development jumbo could be allowed to drill the next round. Typically, within about 2.5-3 hours from the completion of spraying, the heading was deemed safe for re-entry. This shows an improvement over previous practice where a full shift (6–8 hours or more) might pass before the next cycle. Throughout the trial, geotechnical instrumentation (convergence pins, shotcrete strain gauges) was installed in a few locations to monitor ground movement and shotcrete performance. No significant deformations or instabilities were recorded in the trial headings, and the immediate shotcrete layer effectively controlled minor rock spalling that was previously observed soon after blasting in unsupported walls. This provided confidence that the expedited cycle did not compromise ground control. RESULTS The introduction of ICS at Inmaculada yielded measurable improvements across several performance indicators. These results are drawn from a three-month trial period in two development headings where the ICS process was implemented and closely monitored. Equivalent baseline data (from similar headings with traditional support cycle) were used for comparison. 3.1 Cycle time and advance rate The most striking outcome was the reduction in total cycle time per round. With conventional support sequencing, the average cycle time (blast to blast) in the trial
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