Concrete Mud-Jacking & Slabjacking SWMS

Concrete mud-jacking and slabjacking is a specialised concrete-lifting technique in which a cementitious grout or polyurethane resin is pumped under pressure through drilled ports beneath a settled slab to lift it back to grade. The work combines high-pressure injection plant, powered mobile pumping units, cement-based slurries and confined access to drive-slabs, driveways, warehouse floors, footpaths and industrial pavements. Hazards include struck-by from moving plant and hoses, high-pressure fluid injection injury, uncontrolled slab movement or shear, alkaline burns from cement slurry, silica exposure during core-drilling of injection ports, manual handling of hoses and grout bags, and slip/trip risks from spilled material.

Under the Work Health and Safety Regulation 2025 (NSW), this activity involves powered mobile plant and is high risk construction work under section 291(o). A Safe Work Method Statement is therefore required under section 299 before work commences. Controls follow the hierarchy in section 36, with engineered exclusion zones, competent operators, and documented consultation under section 47.

Hazards identified

12 hazards covered, sorted by priority.

Control measures

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

1. 1Eliminate where practicable by scheduling mud-jacking outside operational hours in warehouses and industrial sites so powered mobile plant does not share the work zone with other traffic or workers.
2. 2Substitute cementitious grout with lower-pressure polyurethane resin systems where slab geometry permits, reducing injection pressures and hose whip potential; where isocyanate resins are used, apply the substitution assessment in the SafeWork NSW Code of Practice: Managing Risks of Hazardous Chemicals in the Workplace.
3. 3Establish engineered exclusion zones around the mud-jacking rig and pump truck using physical barriers, with spotter-controlled entry when plant is moving, in accordance with AS 2601 for demolition-adjacent works and AS 1742.3 for traffic control at worksites.
4. 4Locate and mark underground services via Before You Dig Australia (BYDA) enquiry, ground-penetrating radar and hand-probing prior to core-drilling; maintain minimum clearances per SafeWork NSW Code of Practice: Excavation Work.
5. 5Use on-tool water suppression or H-class HEPA extraction on core-drills to control respirable crystalline silica below the workplace exposure standard of 0.05 mg/m³ (8-hour TWA); conduct air monitoring where exposure is reasonably likely under section 50 of the Regulation.
6. 6Inspect and pressure-test all grout hoses, couplings, whip-checks and injection ports before each shift; tag out damaged equipment and use hose restraints (whip-socks) on every coupling per AS 4041 pressure piping principles.
7. 7Monitor slab movement during lifting using laser levels, dial gauges or string lines; establish stop-lift criteria and require all personnel to stand clear of the lifting slab during pressurisation.
8. 8Implement a permit-to-work and exclusion-zone system for high-pressure injection; only operators trained on the specific rig may operate pump controls, and a second competent worker monitors injection ports.
9. 9Provide traffic management in accordance with AS 1742.3 and a site-specific Traffic Guidance Scheme where work is on or adjacent to roads, driveways or trafficked yards.
10. 10Provide PPE selected to AS/NZS 1715 and 1716 (P2 respirators, or air-fed for isocyanate work), AS/NZS 1337.1 eye protection, AS/NZS 2210.3 safety footwear, chemical-resistant gloves (AS/NZS 2161.10.1), hi-vis to AS/NZS 4602.1, and AS/NZS 1270 hearing protection.
11. 11Provide health monitoring under sections 368–378 of the Regulation for workers exposed to crystalline silica and isocyanates, and emergency eyewash/shower facilities within 10 seconds' travel of grout-handling areas per AS 4775.
12. 12All workers must hold CPCCWHS1001 (White Card); the SWMS must be developed in consultation with workers under section 47 of the WHS Act, signed on by all crew, and reviewed under section 302 of the Regulation whenever controls change, an incident occurs, or a new hazard is identified.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A concreting contractor is engaged to re-level a settled 180 m² concrete apron at a distribution centre in Wetherill Park, western Sydney. The apron has dropped 45 mm at construction joints from sub-base washout, and the client requires works completed over a weekend to avoid interrupting forklift movements. The crew mobilises a truck-mounted grout pump, a track-mounted core-drill and a compressor into the yard. Before starting, the supervisor delivers a toolbox talk on the SWMS, confirms all workers hold CPCCWHS1001, and workers sign on. A BYDA search and GPR scan identify a live 400 V feeder 300 mm below the slab; drilling patterns are re-planned to maintain 500 mm clearance. Exclusion zones are set with barrier mesh; a spotter controls plant movement. Core-drilling uses wet suppression to control silica. During injection, dial gauges monitor slab rise; a whip-check secures each coupling. When a hose coupling weeps at 1,800 kPa, the crew depressurises before intervening. The SWMS is reviewed and re-signed under section 302 to capture the revised drilling offsets.

Related legislation

• Work Health and Safety Act 2011 (NSW)
• Work Health and Safety Regulation 2025 (NSW)
• Environmental Planning and Assessment Act 1979 (NSW)
• Protection of the Environment Operations Act 1997 (NSW)
• Roads Act 1993 (NSW) — for works on or adjacent to public roads
• Dangerous Goods (Road and Rail Transport) Act 2008 (NSW) — for transport of polyurethane resin components

Frequently asked questions