Shotcrete / Sprayed Concrete SWMS

Shotcrete and sprayed concrete application involves pneumatically projecting cementitious material at high velocity onto tunnel linings, retaining walls, pool shells, and slope stabilisation surfaces. The process — whether wet-mix or dry-mix — generates respirable crystalline silica dust, high-pressure hose whip energy, rebound projectiles, and alkaline chemical exposure, frequently in confined or partially enclosed excavations. Under WHS Regulation 2011 r291, this work constitutes High Risk Construction Work because it involves pressurised systems, silica-bearing materials, work in or near excavations, and structural support installation. A documented Safe Work Method Statement must be prepared, signed by all workers, and kept available on site for the duration of the activity. This SWMS template addresses the specific hazard profile of nozzle operation, mix delivery, and rebound management in line with AS 3850, AS/NZS 4576, and the model Code of Practice for Construction Work.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Where design permits, substitute cast-in-place or precast concrete panels for sprayed application to remove pressurised delivery and rebound hazards entirely from the scope.
2. 2Elimination — Eliminate dry-mix shotcrete in favour of wet-mix processes for any work where silica dust generation cannot be otherwise controlled below the 0.05 mg/m³ workplace exposure standard.
3. 3Substitution — Substitute alkali-free liquid accelerators in place of caustic sodium aluminate powders to reduce dermal corrosion risk and airborne alkaline particulate per SDS Section 8 requirements.
4. 4Substitution — Use pre-bagged silica-reduced cementitious mixes with documented RCS content below 1% where structural specification permits, verified through batch certificates.
5. 5Engineering — Install local exhaust ventilation with HEPA filtration at tunnel portals, wet-suppression rings at the nozzle, and forced-air dilution ventilation delivering minimum 0.5 m/s face velocity per AS 1668.2.
6. 6Engineering — Fit whip-check safety cables, swaged couplings rated to 1.5× working pressure, and automatic shutdown interlocks on pump delivery lines compliant with AS 4041 pressure piping standards.
7. 7Administrative — Implement exclusion zones of minimum 6 metres from the nozzle, pre-start hose pressure-test at 1.5× operating pressure, and 2-hourly rotation of nozzle operators to limit fatigue.
8. 8Administrative — Conduct atmospheric monitoring for oxygen, dust and accelerator vapour every 30 minutes in confined work areas, with documented results retained for 30 years per WHS Reg r50.
9. 9PPE — Issue P2/P3 powered air-purifying respirators with full-face shield, AS/NZS 1337.1 impact eye protection, chemical-resistant nitrile gauntlets, and AS/NZS 4501 alkali-resistant coveralls.
10. 10PPE — Provide hearing protection rated SLC80 26 dB minimum for nozzle operators, AS/NZS 2210.3 toe-protective gumboots, and high-visibility garments meeting AS/NZS 4602.1 day/night class.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a coastal residential pool shell project, the nozzle operator and pump tender arrive for the 6:30 am pre-start brief. The supervisor opens the Shotcrete SWMS on a site tablet and walks the two-person crew through the hazard register, focusing on rebound trajectory given the curved shell geometry and the new alkali-free accelerator introduced last week. The crew identifies that the deep-end exclusion zone overlaps with the formwork carpenter's access path, so the supervisor adjusts the sequence — carpentry stops during spraying windows, documented on the SWMS amendment line with both workers initialling. The nozzleman confirms his PAPR has been fit-tested within 12 months, the whip-check cable is installed on the 65 mm delivery line, and atmospheric monitoring is not required as the work is open-air. Both workers sign the SWMS sign-on register before the pump is primed. Two hours into the pour, the delivery line partially blocks. The operator references the SWMS blockage-clearance procedure rather than improvising: pump is depressurised, the line is depressurised at the relief valve, and the blockage is cleared with the nozzle pointed into the rebound trench. Work resumes, with the incident logged as a near-miss on the back page for the next toolbox talk.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Crystalline Silica — National Strategy + CoP

Frequently asked questions