Attacks: Slam +4 1d8.
Immunity: Charmed, Exhausted, Frightened, Paralyzed, Petrified, Poisoned.
They can understand common, but they cannot speak. These constructs take instructions literally.
Silt and Ash are more powerful their stats are modified in the following way:
AC +2 (They have on armor made of an old car)
Attacks: Slam +6 1d8
They can speak, though they only tell the truth and although they take everything literally as well, they are more able to understand the intent behind an instruction.
To repair the constructs you need to cast Stone Shape on them. Each casting will repair 25 hit points. This is a 4th level spell, pg 278 PHB.