Collocations for mortar - noun

heavy
They could not move their heavy mortars over the swampy ground.

be armed with, have
Their troops were armed with mortars and machine guns.

fire

burst, explode
The occasional mortar burst near our truck.

land
hit sth

attack, fire
We were under constant mortar fire.

bomb, shell
hit by a mortar shell

round
platoon
carrier

Mortar is used before these nouns:
attack, barrage, bomb, fire, mix, round, shell