I would like to know the way to stiffen concrete (not too waterly)
while still allow me enough time to work on it.

What I am trying to do is to level the basement floor. My floor is not
level - the difference from one side to another side is around 3
inches. In order to level the floor, I am supposed to use concrete to
build up a dam around the edge of the basement wall, then I can use a
long wood block (2x4) that rides on the dam to level the floor. My
question is about whether the concrete will be too waterly to hold
itself up, especially in the area that I need to build the dam to 3
inches tall.

I guess I should add less water into the concrete mix to make sure it
is stiff enough. But I am afraid that the concrete will dry too fast
that doesn't give me enough time to build the dam very nicely. I guess
making small batches will help in this situation. I am just wondering
whether there is other alternatives.

I am planning to use concrete that has pre-mixed with sand (not small
stones). I mention this just in case this matters.

Thanks in advance for any tip.

Jay Chan

"Jay Chan" wrote in message
om...
I would like to know the way to stiffen concrete (not too waterly)
while still allow me enough time to work on it.

What I am trying to do is to level the basement floor. My floor is not
level - the difference from one side to another side is around 3
inches. In order to level the floor, I am supposed to use concrete to
build up a dam around the edge of the basement wall, then I can use a
long wood block (2x4) that rides on the dam to level the floor. My
question is about whether the concrete will be too waterly to hold
itself up, especially in the area that I need to build the dam to 3
inches tall.

I guess I should add less water into the concrete mix to make sure it
is stiff enough. But I am afraid that the concrete will dry too fast
that doesn't give me enough time to build the dam very nicely. I guess
making small batches will help in this situation. I am just wondering
whether there is other alternatives.

I am planning to use concrete that has pre-mixed with sand (not small
stones). I mention this just in case this matters.

The hardening process with concrete isn't the result of drying--it is from a
chemical process involving hydration of the lime in the cement. Using very cold
water will slow the hydration process somewhat as well as doing the work in a
cold air temperature (above freezing). Adding excess water to a mix will slow
the set time by separating the cement particles with water. This causes a soupy
mix which takes some extra time for the cement particles to compact sufficiently
for them to bond together and results in a weak and porous finished product.

There are admixtures used by readymix companies which will extend the set time
(delayed set) such as lignosulfonate. Check with the local suppliers for an
"extended set admixture" or "delayed set admixture"

Regards,

John

What you are proposing requires a lot of concrete, do you have any idea
how much that is going to weigh? Do you know how hard it is to move around
and get the proper level ( I doubt if you really want it level, normally you
want it to drain.).

Have you worked a slab that large before? Even a smallish slap requires
a crew of experienced people working together, and then it is hard work.
Working in a basement is usually more difficult than working on the ground.

I really think you should reconsider this idea of doing it yourself.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math


"Jay Chan" wrote in message
om...
I would like to know the way to stiffen concrete (not too waterly)
while still allow me enough time to work on it.

What I am trying to do is to level the basement floor. My floor is not
level - the difference from one side to another side is around 3
inches. In order to level the floor, I am supposed to use concrete to
build up a dam around the edge of the basement wall, then I can use a
long wood block (2x4) that rides on the dam to level the floor. My
question is about whether the concrete will be too waterly to hold
itself up, especially in the area that I need to build the dam to 3
inches tall.

I guess I should add less water into the concrete mix to make sure it
is stiff enough. But I am afraid that the concrete will dry too fast
that doesn't give me enough time to build the dam very nicely. I guess
making small batches will help in this situation. I am just wondering
whether there is other alternatives.

I am planning to use concrete that has pre-mixed with sand (not small
stones). I mention this just in case this matters.

Thanks in advance for any tip.

Jay Chan

There are admixtures used by readymix companies which will extend the
set time (delayed set) such as lignosulfonate. Check with the local
suppliers for an "extended set admixture" or "delayed set admixture"

Thanks for the pointer. I will check it out.

Jay Chan

This actually requires a fair amount of skill, and your question is really
simplistic. Have you ever even finished a slab before? I would suggest
hiring this out - even if you think you can't afford it.

You are quite right to say that. Now, after having tried and failed to
level the floor myself (two months ago), I would think that I should
have forgot about the idea of leveling the floor (for putting tiles)
and live with the uneven floor and bare concrete floor. But now I am
at the point of no return. I will have to get it done.

Pro finishers get a much better deal on concrete. When you also factor
in your time and poor results, I think you will find a pro to be a
bargain.

If I could started this over with, I would be better off hiring this
out. But I am now so close to the finish-line. I really want to get it
done.

Various extenders are available - but they only extend the set by, at most,
90 minutes.

90 minutes is more than enough for me. This means using extender is a
good idea for me. Thanks.

If your old floor is sinking - you may be heading down the wrong road
anyway.

Luckily, the floor is not sinking. The concrete floor was not leveled
properly when the house was constructed back in 1950's. I have a
feeling that the basement was not meant to be finished when the house
was constructed. Therefore, making it level was never a requirement
back then.

Jay Chan

I'd use forms to cast the dam, like a small kerb, then pour relatively
wet crete and let it find its own level with minimum striking.

Yours is a good idea. Now, I just need to find the right material to
build the form and prevent the thinly poured concrete from leaking
out. Then, I don't need to worry about stiffening concrete and
entending work time.

Be sure you use a concrete that will stand up to use in a thin
pour - I'm not certain, but I think you should use one of the
vinyl reinforced or surfacing concretes.

I probably will use leveling compound. They hold up quite well in thin
pour based on my experience in my past failed attempt to level the
floor. When I tried to knocked out the high spots that I mistakenly
created, I have a hard time to knock it out if the high spots were
make from leveling compound. The down side is that leveling compound
is quite expensive. But I should not need that much if I only use it
to form the dam around the wall.

Thanks.

Jay Chan

What you are proposing requires a lot of concrete, do you have any idea
how much that is going to weigh? Do you know how hard it is to move around
and get the proper level

You are exactly right. From my failed attempt to level the floor two
months ago, I know that this requires a lot of concrete (and the many
bags of concrete were very heavy). Luckily, I have already raised the
low area to within 1/2" to 1" of the leveling line. I have seen the
end of the tunnel, and I cannot wait to get this over with.

For anyone who is reading this thread and is thinking of leveling a
basement floor by himself, I have two suggestions:
1. You may find that living with bare concrete floor or painted
concrete floor actually is not bad -- as compared to the effort of
trying to level a basement floor.
2. You may find that spending the money to fire a pro to do this may
be more economical than doing this yourself.

( I doubt if you really want it level, normally you want it to drain.).

Actually, I want it to be level because I want to put tiles over it.
The other side of the basement is left unfinished, and the drain hole
is in that side of the basement.

Have you worked a slab that large before? Even a smallish slap requires
a crew of experienced people working together, and then it is hard work.
Working in a basement is usually more difficult than working on the ground.

I really think you should reconsider this idea of doing it yourself.

Yes, you are right. This is really not a DIY kind of thing. But too
late for me. I have already spent so much effort on this, and I have
already emotionally committed to this project. If I could start this
over with, I will either hire a pro, or I will just learn to live with
the bare concrete floor.

Jay Chan