In my basement this last weekend, I bought 25-60lb bags of pre-mix
concrete general use. I mixed two bags at a time with approx. 1.25
gallons of water, the instructions called for 1/2 gallon per bag, no
more than .75 gallon per bag. I mixed it with a shovel for about 5
minutes or until I couldn't see any more dry mix. It was definitely not
runny and not dry but seemed just right. I tried to use a steel trowel
to smooth it after I couldn't see any more sheen or water which the
instructions said, but I couldn't get it smooth. It seemed too
textured, rocky, maybe I waited too long before I started smoothing it.
Well, now its day 3 of curing, I took a broom to the new concrete and
swept up a couple dustpans full of small pebbles and small mix
particles. The texture of the concrete seems rougher than ever now. I
took a hose and wetted it down. From just picking at the top surface
with my finger, I can pick out small pebbles and little crumbles of
concrete. It makes me pretty upset, I followed all the instructions to
a T, but now I doubt whether I did this right, any idea why this is
happening, why it's so coarse, rough looking, why I can just pick
away at the top and it crumbles off after 3 days of curing? Its 3"
thick in my basement and I didn't have any fun doing this job in the
first place. In the end it will be covered up by some leveling compound
and tile, but I just want to make sure this isn't going to crumble
away underneath everything to only be replaced in a few years. The
instructions call for 5 days of curing, maybe I am too impatient.
Thanks for any help!