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Home > Archive > Home Repair forum > February 2008 > Dry mix concrete question.
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Dry mix concrete question.
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| I've used the ready mixed in a bag and mix my own by adding cement to the
con mix. I usually get a better finish with the ready mix - smoother, more
butter. The con mix consists of sand and 3/4" or smaller rocks. I'm using 1
part cement to 5 part con mix ratio. The problem is most of the rocks are
large with very few aggregates smaller than 1/2" so the results are lumpy
after bull floating. I needed to use the tamper to drive the rocks down
before bullfloating. Both supplier in my are has this problem regarding the
lumpiness.
Am I doing something wrong or should I add smaller rocks to the mix
(eliminate the temping process) to get a smooth finish like the ready mix
bags?
Also for straight lines, an edger is great but on radius bends where the
edger doesn't conform to the curves, what tools should I use?
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| Robert Allison 2008-02-27, 3:25 am |
| Frank wrote:
> I've used the ready mixed in a bag and mix my own by adding cement to the
> con mix. I usually get a better finish with the ready mix - smoother, more
> butter. The con mix consists of sand and 3/4" or smaller rocks. I'm using 1
> part cement to 5 part con mix ratio. The problem is most of the rocks are
> large with very few aggregates smaller than 1/2" so the results are lumpy
> after bull floating. I needed to use the tamper to drive the rocks down
> before bullfloating. Both supplier in my are has this problem regarding the
> lumpiness.
>
> Am I doing something wrong or should I add smaller rocks to the mix
> (eliminate the temping process) to get a smooth finish like the ready mix
> bags?
Are you using 1 part cement, 2 parts sand, and 3 parts aggregate?
That should do it. What kind of aggregate are you using?
Larger aggregate will contribute to higher PSI, so I wouldn't put
in smaller unless you don't care about strength. I haven't had
lumpiness problems, so I can't help much.
> Also for straight lines, an edger is great but on radius bends where the
> edger doesn't conform to the curves, what tools should I use?
We have always used standard radius edgers. When the radius wall
gets short, you sometimes have to lift up the front of the edger
and just use about half of it to make the radius. When doing
this, it is important to have the curved edge radius edger. Here
is an example:
http://www.marshalltown.com/catalog...asp?edino=14190
--
Robert Allison
Rimshot, Inc.
Georgetown, TX
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"Robert Allison" <rimshot27@verizon.net> wrote in message
news:ZS4xj.6149$xg6.2625@trnddc07...
> Frank wrote:
>
>
> Are you using 1 part cement, 2 parts sand, and 3 parts aggregate? That
> should do it. What kind of aggregate are you using? Larger aggregate will
> contribute to higher PSI, so I wouldn't put in smaller unless you don't
> care about strength. I haven't had lumpiness problems, so I can't help
> much.
>
Don't know what the ratio is as its pre mixed sand and 3/4" aggregate. I get
15 yards and they dump it on my driveway. All its needed is water and
cement. Vibrating the concrete helps and the walk behind tamper is great
pushing the 3/4" lumps down, leaving more butter on the surface. Still not
as good as the pre mixed bags where you just add water.
>
> We have always used standard radius edgers. When the radius wall gets
> short, you sometimes have to lift up the front of the edger and just use
> about half of it to make the radius. When doing this, it is important to
> have the curved edge radius edger. Here is an example:
>
> http://www.marshalltown.com/catalog...asp?edino=14190
>
>
This is the tool I use and having problems with small radius curves even
after lifting the edger up. The problem is its too long but I have an extra
one and will saw it off and play around with it.
> --
> Robert Allison
> Rimshot, Inc.
> Georgetown, TX
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| I thought everyone had one of these in the collection"
http://www.concretesupplyhouse.com/page/CSHL/PROD/CF113 I sure
don't use it often, but when needed . . . . ..
Never throw out old edgers, cut some real narrow to get past
anchor bolts, etc. cut some short.
--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
dgriff237@7cox.net
" Frank" <noreplay@nothome.net> wrote in message
news:JomdncGrf8pKhVvanZ2dnUVZ_vOlnZ2d@comcast.com...
>
> "Robert Allison" <rimshot27@verizon.net> wrote in message
> news:ZS4xj.6149$xg6.2625@trnddc07...
>
> Don't know what the ratio is as its pre mixed sand and 3/4"
> aggregate. I get 15 yards and they dump it on my driveway. All
> its needed is water and cement. Vibrating the concrete helps and
> the walk behind tamper is great pushing the 3/4" lumps down,
> leaving more butter on the surface. Still not as good as the pre
> mixed bags where you just add water.
>
>
>
> This is the tool I use and having problems with small radius
> curves even after lifting the edger up. The problem is its too
> long but I have an extra one and will saw it off and play around
> with it.
>
>
>
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| Jim Elbrecht 2008-02-28, 9:25 am |
| Frank" <noreplay@nothome.net> wrote:
-snip-
>Don't know what the ratio is as its pre mixed sand and 3/4" aggregate. I get
>15 yards and they dump it on my driveway. All its needed is water and
>cement.
I can't imagine that being a good idea. I am anal about keeping my
cement/sand/gravel ratios.
How much cement do you add to your premix? That premix has to vary
from a 1-3 to a 3-1 by the time it ride in a truck, gets dumped, gets
moved around while shoveling-- and hopefully it is covered as a few
drops of rain will bring all your sand to the bottom of the pile.
What are you mixing it in? Are you letting it set up too much before
screeding?
Jim
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"DanG" <dgriff23@7cox.net> wrote in message
news:Wvqxj.8517$f8.5759@newsfe23.lga...
>I thought everyone had one of these in the collection"
> http://www.concretesupplyhouse.com/page/CSHL/PROD/CF113 I sure don't use
> it often, but when needed . . . . ..
>
Thanks DanG, this is a cool tool. Don't see it in the local big box stores.
>
> Never throw out old edgers, cut some real narrow to get past anchor bolts,
> etc. cut some short.
>
> --
> ______________________________
> Keep the whole world singing . . . .
> DanG (remove the sevens)
> dgriff237@7cox.net
>
>
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"Jim Elbrecht" <elbrecht@email.com> wrote in message
news:2scds3p9srotqrd918r47nf22argb26b6a@4ax.com...
> Frank" <noreplay@nothome.net> wrote:
>
> -snip-
>
> I can't imagine that being a good idea. I am anal about keeping my
> cement/sand/gravel ratios.
>
> How much cement do you add to your premix?
One to five ratio.
That premix has to vary
> from a 1-3 to a 3-1 by the time it ride in a truck, gets dumped, gets
> moved around while shoveling-- and hopefully it is covered as a few
> drops of rain will bring all your sand to the bottom of the pile.
>
> What are you mixing it in?
http://www.constructioncomplete.com...ementMixer.html
This one except its by Husky and about $200 cheaper - I had this Imer before
and couldn't tell the difference from the Husky. Very nice for small jobs, I
also have a Red Lion mixer and its crap.
Are you letting it set up too much before
> screeding?
>
No, at time of screening my feet would still sink into it. Tamping helps a
lot. If I have more projects, I would get the dual roller temper - such a
time saver and eliminate the concrete mess on my pans after temping.
http://www.amazon.com/Roseburrough-...04214433&sr=1-1
> Jim
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| Jim Elbrecht 2008-02-28, 1:25 pm |
| Frank" <noreplay@nothome.net> wrote:
>
>"Jim Elbrecht" <elbrecht@email.com> wrote in message
>news:2scds3p9srotqrd918r47nf22argb26b6a@4ax.com...
>
>One to five ratio.
There's one problem. Sounds like you're shooting for the very
common and good all around, 1,2,3 mix. But even if you managed
to get lucky and you got 2 parts sand and 3 parts gravel- [and I
still don't see that as likely] once mixed your 2+3 probably equals
about 4 - not 5.
I use #2 crushed stone & mason's sand. . . . I just tried it- 3 stone
plus 2 sand = just over 4 of the mix.
Your smaller stone might have a different yield. But I still suspect
that the top of that pile is more like 1 sand & 3-4 stone, and the
bottom will be 3-4 sand to one stone. Especially if it is as dry as
it ought to be.
-snip-
>
>http://www.constructioncomplete.com...ementMixer.html
>
>This one except its by Husky and about $200 cheaper - I had this Imer before
That's an awful lot of mixing - 15 yards of sand/gravel. I was
looking at a job half that size a couple summers ago and my
brother-in-law talked me into the redi-mix truck. Ended up
actually saving me money after I called around a bit. Done in 1/2 a
day, more options, and a better mix besides.
We were just doing footings which didn't have to be pretty- but it
sounds like you might be doing a sidewalk/patio. [I hope not a
driveway because you've started with a pretty weak mix if it is.] I'd
be thinking about it though if I needed more than a couple yards of
concrete. [you pay extra for a short load- when I did it, I was
quoted a price for 4 yards- then raised it to 5 yards and the last
yard only cost me about $10] Even at the high price per yard it
was cheaper than buying sand, gravel and portland.
Jim
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| Robert Allison 2008-02-28, 1:25 pm |
| Jim Elbrecht wrote:
> Frank" <noreplay@nothome.net> wrote:
>
>
>
>
> There's one problem. Sounds like you're shooting for the very
> common and good all around, 1,2,3 mix. But even if you managed
> to get lucky and you got 2 parts sand and 3 parts gravel- [and I
> still don't see that as likely] once mixed your 2+3 probably equals
> about 4 - not 5.
>
> I use #2 crushed stone & mason's sand. . . . I just tried it- 3 stone
> plus 2 sand = just over 4 of the mix.
>
> Your smaller stone might have a different yield. But I still suspect
> that the top of that pile is more like 1 sand & 3-4 stone, and the
> bottom will be 3-4 sand to one stone. Especially if it is as dry as
> it ought to be.
>
> -snip-
>
>
>
> That's an awful lot of mixing - 15 yards of sand/gravel. I was
> looking at a job half that size a couple summers ago and my
> brother-in-law talked me into the redi-mix truck. Ended up
> actually saving me money after I called around a bit. Done in 1/2 a
> day, more options, and a better mix besides.
>
> We were just doing footings which didn't have to be pretty- but it
> sounds like you might be doing a sidewalk/patio. [I hope not a
> driveway because you've started with a pretty weak mix if it is.] I'd
> be thinking about it though if I needed more than a couple yards of
> concrete. [you pay extra for a short load- when I did it, I was
> quoted a price for 4 yards- then raised it to 5 yards and the last
> yard only cost me about $10] Even at the high price per yard it
> was cheaper than buying sand, gravel and portland.
>
> Jim
>
Not to mention spending all the energy to mix it. Even with a
mixer, it is a lot of work. Ready mix trucks are the only way to
go for anything over a yard, if you ask me. Plus, as you
mentioned, the mix is waaaaay better. (And guaranteed if you pour
a test cylinder or two.)
--
Robert Allison
Rimshot, Inc.
Georgetown, TX
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"Robert Allison" <rimshot27@verizon.net> wrote in message
news:_QCxj.34457$6h7.15758@trnddc04...
> Jim Elbrecht wrote:
>
> Not to mention spending all the energy to mix it. Even with a mixer, it
> is a lot of work. Ready mix trucks are the only way to go for anything
> over a yard, if you ask me. Plus, as you mentioned, the mix is waaaaay
> better. (And guaranteed if you pour a test cylinder or two.)
>
> --
> Robert Allison
> Rimshot, Inc.
> Georgetown, TX
I hear you guys but its just the wife and me, not 7 guys and 3 finishers.
Next time I'll try the self consolidating concrete - no need to vibrate,
screed or even spread it.
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| Jim Elbrecht 2008-02-29, 9:25 am |
| Frank" <noreplay@nothome.net> wrote:
>
>"Robert Allison" <rimshot27@verizon.net> wrote in message
>news:_QCxj.34457$6h7.15758@trnddc04...
-snip-[color=darkred]
-snip-[color=darkred]
-snip-[color=darkred]
>I hear you guys but its just the wife and me, not 7 guys and 3 finishers.
-snip-
There is never time/money to do things right the first time- but there
is always time/money to do it over when it fails. <g>
Except for special occasions when I call my son or brother-in-law, I
work alone, so I know what you're up against. But concrete is one
of those occasions. You don't say what you're making. If it's
a driveway- forget it, take out what you've done and start over.
If it is squares for a sidewalk or patio you can remove what you've
done in a few years when it gets too ugly to look at.
But at any rate- you've started off with an impossible task. IMHO
there is no way to make a decent mix using premixed sand and gravel.
[maybe if you did the work every day, could eyeball the slurry in the
mixer and tune it up as you go-- but you and I can't do that]
If you and your wife can handle all the bullwork, find a mason that
will let you be helpers, offer your services and see what he'd get to
do the job. I'll bet there's a guy with all the tools that make life
easy-- the contacts to get you the best price on concrete-- and you'll
end up with less work- probably very little more money- and a job that
will last as long as concrete ought to.
Hang onto your mixer for pouring posts & doing small repairs- not some
honking 15yard pour.
Good luck-
Jim
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