which concrete to choose

Started by tesa, April 11, 2010, 08:37:47 AM

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tesa

so the guy at home depot says to use this concrete mix that is rated 8000 psi.  he says
no rebar is needed if we go with that strength

regular fast set is rated at 3000 psi

the price between the two is failry big for our budget, and it seems the majority of the cost is in concrete

can someone clear up which concrete mix we should go with?

i'm willing to pay the price for the 8000 psi is its what we really need, but is it over-kill for the 1 1/2 story?

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

MikeT

What/how much are you pouring?  If you are going with bags, then I hope it is not too many.  You can mix your own pretty (actually very) cheaply using the basic ingredients and change the proportions to create the relative qualities you want.    But if it is only a small amount, then I can see why the convenience of the redimix bags would win out.  For larger quantities (a few yards or more) you can look at a cement truck, or some places have trailers that they fill with concrete and you can haul it to your site yourself (if it is close enough).

mt


MountainDon

I would use steel reinforcing bar and 3500 to 4000 psi concrete. There's no need to spend $$ on expensive high strength concrete especially if you are buying bagged premixes. I've never seen 8000, seen 5000 psi bagged, not to say 8000 does not exist.

Commercially the high strength mix is used when lighter, less massive concrete beams are required. They use steel in those though. I don't think I'd want to omit the steel even with the 5000 psi bagged mixes.

Sand, grave, portland cement is an easy to to recipe at less cost than bags.
Just because something has been done and has not failed, doesn't mean it is good design.

tesa

we'll be doing 17 footers 24" x 12"

we'd have to rent a boom, and thats IF the truck could even get to us, so i was pricing it out with us doing it,
then i was gonna call a few companies and see what their charges would be

we'd like to do it ourselves, i bet its almost always gonna be cheaper, but our time is valuable too, so i'm
not opposed to contracting it out, i just want whats best for our budget and our backs

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

tesa

i think i only saw 3K psi concrete, then we saw 5K, then the guy at the pro desk showed us the 8K

how might one mix their own using the sand, gravel, portland components?

daniel thought the pro desk guy was trying to help us by selling us the 8K concrete so we wouldn't have to use
re-bar, which is also something we've never done

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing


Beavers

3-2-1 is what I used for mixing my own.

3 parts gravel
2 parts sand
1 part cement

I'm not sure what PSI this mix would be, but it seems like the standard mix that people have used for ever.  I actually used about 1 1/2 parts cement for a little extra strength.

Like Don said, you always need steel in concrete.

MikeT

Tesa, you lost me with saying 17 footers.  Do you mean piers?   And typically there is another dimension you are dealing with Length, width, and thickness.

You might look at mixing the raw materials yourself in a small mixer you bring to the site.  I will likely do this because it gets me the concrete I need relatively cheaply but I am not going through the painful work of mixing in a wheelbarrow....

There is a cost to all this stuff, and only you know what your time and effort are worth.