Concrete, Steel Erection, and Demolition

Concrete and masonry construction involves unique hazards including formwork collapse, impalement, chemical burns from wet concrete, and falling materials.

**Key concrete hazards:** - Formwork collapse from improper design or overloading - Impalement on protruding reinforcing steel (rebar caps required) - Chemical burns from wet concrete (highly alkaline, pH 12-13) - Silica exposure from cutting or grinding cured concrete - Struck-by from concrete pump boom failure - Confined spaces in forms and vaults **Masonry construction:** - Limited access zones must be established on the unscaffolded side of masonry walls - Walls over 8 feet must be adequately braced - Bracing must remain until permanent supporting elements are in place **Concrete pump safety:** The concrete pump boom creates a significant struck-by hazard. Workers must: - Stay outside the swing radius of the pump boom during operation - Never position themselves under the boom - Establish exclusion zones around the pump and delivery hose - Understand that hose kinking can cause explosive pressure release **Post-tensioned concrete:** Post-tensioned slabs and beams contain high-energy tendons under extreme tension. Cutting into post-tensioned concrete requires engineering guidance. A snapped tendon can cause catastrophic structural failure and propel steel through the air with lethal force.

Lift slab construction:

In lift-slab construction, concrete slabs are cast at ground level and then lifted up columns using hydraulic jacks. This method creates unique hazards:

• Slabs must be lifted simultaneously from multiple jack points to maintain level
• Catastrophic collapse can occur if jack synchronization fails
• OSHA requires engineering supervision and a lift plan for each slab
• Temporary connections to columns must be maintained until permanent connections are completed

Concrete pump hose whip:

A concrete pump hose under pressure and filled with concrete is heavy and rigid. If a coupling fails or the hose is abruptly disconnected, the end of the hose can whip violently - similar to an unrestrained fire hose. Control measures:

• Never stand at or near the discharge end of the hose
• Inspect all hose couplings before each pour
• Keep workers out of the hose swing radius
• Have a clear abort signal between the pump operator and hose handler