At one point, a shirtless Nathanial Paton, 25, scattered about 80 Alfred Deakin High School students when he drove onto the oval and blasted the horn between 10 to 15 times.

He then lowered the scraper and left a 12x2-metre gouge on the grass.

Paton came within five metres of a group of children and yelled out "there's a long jump pit for you" before he drove away.

Paton's 20-minute joyride in September 2013 came to an end when police stopped him on Martin Street in Curtin about 12.50pm.

Paton pleaded guilty in the ACT Magistrates Court to drug possession, vehicle theft, dangerous driving, property damage and drug-driving.

He appeared for sentence before Chief Magistrate Lorraine Walker on Wednesday.

Court documents said the police had been inundated with calls from concerned motorists as the road scraper drove erratically south along Northbourne Avenue and into the inner south.

Members of the public reported that the scraper had run red traffic lights and driven onto the median strip during the joyride, which began about 12.25pm on a weekday.

When he was arrested, Paton told police he thought someone had been trying to kill him,

Officers reported that the offender appeared paranoid and hard to understand, speaking in disjointed sentences and not making sense.

Paton told police he had use methylamphetamine (ice) earlier that morning.

A search of the driver's cabin uncovered a black backpack which contained 2.2 grams of the drug.

During Paton's sentencing, the court heard that he had turned his life around. He had a stable job and had produced clean drug tests for the past year.

Ms Walker sentenced him to 15 months' jail, to be fully suspended on his entering a two-year good-behaviour order.

The chief magistrate also suspended his licence for six months.

Ms Walker warned Paton that he risked jail if he breached the order or reoffended.