James Gill, 39, will be sentenced at Nottingham Crown Court for the attack on Neil Robinson, 75, who hit his head on the concrete floor after being pushed over in an incident on Ranson Road, Chilwell, Nottingham on December 16 last year.
Mr Robinson died in hospital a week later.
Gill, of Station Road, Arksey, pleaded guilty to manslaughter at an earlier hearing.
Court round-up: The latest convictions from Doncaster Magistrates' Court
New plans submitted for 200 homes in Skellow close to the A1 with more potentially near by
Two men hunted after man assaulted and robbed in Doncaster city centre
Plans still in pipeline for ‘rural leisure centre’ in Doncaster with triathlons, outdoor gym, football pitches and holiday cabins
Police hunt knife attacker after man stabbed at Doncaster music festival
Nottinghamshire Police described the incident as “a road-rage incident".
Mr Robinson was taken to Queen's Medical Centre in Nottingham, where he died.
Gill also pleaded guilty to assault occasioning actual bodily harm in relation to another man, and two counts of assaulting an emergency worker, following attacks on two police constables.
He has been remanded in custody since the earlier hearing.
Det Insp Steve Wragg of Nottinghamshire Police said Gill could "expect to face a significant prison sentence for his mindless actions".