Was heißt »Aufbauhelfer« auf Englisch?

Das Substantiv »Aufbauhelfer« lässt sich wie folgt von Deutsch auf Englisch übersetzen:

Englische Beispielsätze

He enlisted as a volunteer.
He put himself forward as a volunteer.
Guernica is a famous painting by Pablo Picasso produced between May and June 1937. Its title refers to the aerial bombing of the town of Guernica on 26 April that same year during the Spanish civil war.
Tom will probably be the first person to volunteer.
What kind of volunteer work does Tom do?
My father’s older brother is a civil servant.
Ask Jacob, the crane operator.
My older sister is a volunteer firefighter.
Tom was the last one to volunteer.
Tom was a volunteer firefighter when he was younger.
Never volunteer for anything.
I used to be a volunteer fireman.
Tom was the first one to volunteer to help us do that.
Tom was the first one to volunteer to help.
I'm a volunteer.
That's not civil disobedience. That's rioting.
Throughout its history, Yemen has experienced 11 civil wars.
I used to volunteer at the food pantry around the corner.
An astronaut's salary is based on the civil service pay scale. Astronauts are ranked between a GS12, which earns $65,140 a year, and a GS13 that earns $100,701 a year.
Now listen to me, children. You must be civil and kind to everyone, and never say a cross word to anyone, and never touch a crumb belonging to anyone else.