Basement Floor New concrete coarse, crumbles, rough, oh no
 

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!

Joe Sloppy wrote:

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? ...

You mixed it too dry. It isn't going to get any better. Anything you
do at this point is futile other than a skim coat over the top thick
enough to hold. You might have gotten better results if you had added
the additional water while still trying to work it, but it's far too
late now.

It reaches almost its complete final strength in 24 hours and will continue
to cure for days/months/years. Not sure where you went wrong. In practice,
the amt of water is really a guide. Your surrounding areas in your hole may
have sucked up some water and your mix was too dry. When finishing, you
trowel the top and 'bring up the cream', thats after about 5 or 10 minutes.
Broom finish is to make it rough, like for sidewalks. That is done one crete
starts to set up. After a day you are pretty much done and SOL.
"Joe Sloppy" wrote in message
oups.com...
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!

On Tue, 30 Aug 2005 12:40:05 -0400, "No" wrote:

It reaches almost its complete final strength in 24 hours and will continue
to cure for days/months/years. Not sure where you went wrong. In practice,
the amt of water is really a guide. Your surrounding areas in your hole may
have sucked up some water and your mix was too dry. When finishing, you
trowel the top and 'bring up the cream', thats after about 5 or 10 minutes.
Broom finish is to make it rough, like for sidewalks. That is done one crete
starts to set up. After a day you are pretty much done and SOL.
"Joe Sloppy" wrote in message


Or you could have gotten a crapy batch of pre-mix that was already
half-cured before you started mixing.

Goedjn wrote:

On Tue, 30 Aug 2005 12:40:05 -0400, "No" wrote:

It reaches almost its complete final strength in 24 hours and will continue
to cure for days/months/years. Not sure where you went wrong. In practice,
the amt of water is really a guide. Your surrounding areas in your hole may
have sucked up some water and your mix was too dry. When finishing, you
trowel the top and 'bring up the cream', thats after about 5 or 10 minutes.
Broom finish is to make it rough, like for sidewalks. That is done one crete
starts to set up. After a day you are pretty much done and SOL.
"Joe Sloppy" wrote in message

Or you could have gotten a crapy batch of pre-mix that was already
half-cured before you started mixing.

Possible but unlikely given his description of not being able to work it
even when he first tried troweling.