His employer was yesterday fined £6,700 over the incident and ordered to pay £8,000 in costs.
Stafford Magistrates’ Court was told that contractor Colin Boon, 55, of West Street, Biddulph, Stoke-on-Trent, was in charge of a gang of road workers sealing a pavement on Wilson Road, Hanford, Stoke-on-Trent, when the incident happened on 13 September 2012.
The injured man, a 36-year-old worker from Stoke-on-Trent, slipped as he climbed from a flat-bed lorry which was next to the mixer.
He put his left leg down to steady himself but it went through the unguarded opening of the mixer. The moving paddles in the mixer severely injured his lower left leg, resulting in amputation below the knee.
The Health & Safety Executive (HSE) investigated the incident and found the guard over the rotating paddles in the petrol-powered mixer had been removed the day before the incident and not replaced.
Colin Boon of West Street, Biddulph, pleaded guilty at an earlier hearing to a breach of Section 3(1) of the Health and Safety at Work etc Act 1974.
Speaking after the hearing, HSE inspector Alastair Choudhury said: "This was an entirely preventable incident and a young man has sustained an injury that will have a huge impact on the rest of his life. Colin Boon failed in his duties to these workers. He was aware the guard had been removed and took no action to prevent use of the machine on the 13 September 2013.
"Guarding on machinery is there for a reason – to prevent people getting hurt. If it is removed, absent or defective, employers are putting employees and others at risk of injury or death. No commercial pressure to take these risks is justified and the potential costs of incidents far outweigh any savings in time or money.
"The mixer should not have been used once the guard had been removed.
"This incident could have resulted in even more serious injuries and today’s sentence sends a message to all employers to carry out work safely. HSE will not hesitate to take action against employers who fail to ensure the health and safety of workers."