Question:
We just finished mudding our garage and in the process, some of the mud
fell on the floor and dried up. When we were all done, we swept most of
the dust out of the garage, but to clean the floor good, we took a garden
hose and rinsed out the garage. Anyway, we took the taping knive to the
concrete ground and scraped up the hardened dried joint compound and now it
looks like we have scuffs in the concrete. Why would this happen? Is the
concrete not dry after 4 months? Is there anything I can do to fix it?
Also, what works best to clean up any remaining joint compound off the
floor?
Answer:
-I had a house built in 1972 and they had the blown ceiling in the
house... every floor in the house had spots of the drywall stuff on it.
it did not matter as the entire house had the floor covered with tile or
carpet... not in the garage, i think the garage floor was scrubbed up to
get the stuff off the floor? but it was the only floor to have the
stuff removed... even after 30 yrs... the laundry room when the tile
came up you could see the 2 in. sized spots of drywall they left there..
looked like white spots... but they did clean up the garage........
-Concrete doesn't "dry", it cures, and it increases in strength as time
goes on. However, standard mix concrete reaches pretty close to its
maximum strength in a month.
It's hard to be sure at this distance, but it sounds like your concrete
is not as hard as it should be. (Maybe there was an impurity in the
mix.) Compare your concrete's resistance to chipping to that of another
piece of concrete if you want to know.
There's nothing you can do at this point to harden the concrete. A
pressure washer will get up the joint compound. If you don't have one,
use muriatic acid, but you're still going to have a mark of sorts.
Painting over will cover everything.
But since it's a garage, just ignore the scuffs.
