What Happened?
Following a lift movement, a section of an interlocking concrete Kelly Block detached and sheared off after the block had been landed on the ground. Thankfully, no-one was injured, though the contractor has initiated a near miss investigation. Kelly Block are large precast concrete blocks, with standard/full blocks weighing between 1 and 1.6 tonnes. These blocks may be used for a wide variety of applications in construction. Whilst the investigation is ongoing, the contractor wishes to share this near miss event with the wider industry to raise awareness and help prevent similar occurrences.
Why it Happened?
The contractor using the Kelly Blocks has engaged the manufacturer and supplier of the Kelly Blocks and requested a full incident investigation, including a review of the block design, manufacturing process and all relevant documentation. Preliminary findings from the contractor’s investigation suggest that the Kelly Block may have been cast in two separate pours, with the failure occurring along a potential cold joint between the sections, resulting in the block shearing at this interface.
Immediate Actions
- The contractor has implemented an immediate suspension on all lifting operations involving these Kelly Blocks pending the outcome of the investigation.
- The contractor also intends to progressively remove and destroy the affected Kelly Blocks as a precautionary measure.
- Kelly Blocks that appear to have been cast in two sections should not be lifted without the manufacturer having supplied a specific design for this arrangement confirming its safety and adequacy – including the safe method of lifting the Kelly Block using any cast in lifting anchor / device.
- This lesson learned has been shared with the CIF to raise awareness of the potential risks associated with these blocks and to help prevent similar incidents or accidents occurring in the future.