Summary
A concrete pump truck was pumping concrete into the walkway of a house while a worker held the end hose. The rubber hose was 20 feet (6 metres) long and had a coupling device attached at the end. The operator of the concrete pump truck saw that the concrete had stopped flowing out of the hose. He pushed the emergency stop button and the pumping stopped. However, compressed air trapped in the supply line behind a blockage forced the blockage to clear suddenly. Concrete burst out of the hose, causing the hose to whip out. The worker holding the hose fell backwards. He struck his head on a piece of scrap lumber and later died of his injuries.

Conclusions

Findings as to causes

• The worker who was holding the end hose of the pump truck was thrown backwards when the hose whipped out. Striking his head on a piece of lumber, he suffered fatal injuries.

• After pumping stopped and the hose was relocated, air got into the pump truck's delivery system. Once pumping resumed, that air became pressurized, causing an eruption of concrete out of the end hose. As a result, the end hose whipped out uncontrollably.
• The end hose was 20 feet long with a coupling attached at the end, contrary to the concrete pump truck manufacturer's instructions. Had the end hose been only 12 feet long with no coupling as recommended, its whipping action would likely have been less violent when the concrete spewed out.
• The two workers who were doing the concrete placing had no training associated with blockages. And the operator of the concrete pump truck was unaware of the danger of allowing the boom to drain.
• Adequate communication among the workers about the hazards associated with concrete pumping operations did not take place.

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