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Posted by Bobk207 on June 29, 2007, 5:32 pm
> On Jun 29, 1:30 pm, spebby...@hotmail.com wrote:
>
> > Thanks RicodJour for your comments. Although I am a little confused
> > now.
>
> > RicodJour from your comments it appears a well constructed base is
> > sufficient. Of course, with the cuts in the slab at an appropriate
> > distance. I think I will get a third bid.
>
> A third bid on two different techniques won't necessarily indicate the
> better construction method. In general you want to get three bids on
> the same thing so you can compare apples to apples.
>
> > One other question: My water well will be in the new garage. Should
> > the slab be isolated from the well's casing? I was thinking building
> > a form around the casing and filling the void between the casing and
> > concrete with pea gravel might be a good solution.
>
> A highly respected, very knowledgeable and long time poster on this
> newsgroup is out of commission at the moment. Here is a thread where
> you can read what he has to say on the matter:http://tinyurl.com/2hyeau
>
> Bob is one of the few guys where I'll concede that his knowledge and
> experience outweigh my own. Don't tell him that - I don't want his
> head to explode. ;)
>
> When you're searching for answers on, well, on almost anything, do a
> google and click on the More link at the top of the results page, then
> click on Groups in the drop down menu. That enables you to search
> newsgroups and is a highly effective tool. Most of these questions
> have been asked and answered before.
>
> R
OP-
Per RIco's comments.....the merits (or lack thereof) of rebar vs fiber
reinforced concrete vs thicker unreinforced concrete have been
discussed & debated a number of times in the last year.
My bias is towards rebar but as Rico pointed out, 3" of concrete cover
to soil is kinda hard to do in a 4" slab. :)
Realistically, you've got to go to at least a 5.5 or 6" slab to
consider rebar
Additionally one normally settles on a design & then bids THAT
design....having two designs & one bid per design really doesn't give
you much info to work with.
I would suggest that you settle on a design and THEN bid it.
Here are some things (& numbers) to consider (my random slab on grade
thoughts)
You've got about 700 lbs of rebar.
You could "spend" the rebar $'s & go with a thicker (adding 2" of
concrete is about 4.5 yds in your pour)
Mix design, placement & curing will have major impact on concrete
strength & future performance.
Scoring your slab into 4 pieces is optimistic...in the 31' direction
that would be 15.5", that would be pushing it a little. For your slab
the MAX distance between cuts is about 12'. I would suggest cutting
31' / 3 & 24' / 2; it's always a tradeoff between more cuts & the
risk of uncontrolled cracks. :(
After the concrete cures, fill the crack with an elastomeric filler,
protects the edge & keeps crap out of it.
Despite my bias towards rebar.....adding thickness to the slab will
probably give you a better performing slab over rebar in a thinner
(thin) slab at lower cost.
IMO thickening the slab will be less than 50% of the rebar cost (SWAG)
The $1100 delta between bids is not all due to the rebar cost, there
is the contractor delta as well
Suggestion:
Ask the fiber mix guy;
1. cost increase to go to a true 6" (also check to see if the
original 4" bid was a 4" guaranteed min)
tell him the increase from 4" to 6" is 4.5 yds
2. cost increase to add rebar (700 lbs; 22 pieces @ 24' & 17 pcs @
31')
My biased recommendation & guessed best performing solution (& lowest
cost near second choice) ......
lose the fiber, go to 6", boost cement content, reduce water, add
rebar, use the fiber contractor
lose the fiber, go to 6", boost cement content, reduce water, no
rebar, use the fiber contractor
cheers
Bob
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