Cincerblock and concrete

[ericarenee]

I'm picking up on the lingo and researching to make sure I ask for the right structure (or asking the right questions) when I talk to a foundation engineer or contractor.

Here's my understanding:

A mat foundation (also called a raft foundation) is basically a flat sheet with deeper structures at the edges of the foundation. It can be reinforced with thicker sections where the high pressure loads are and those sections are tied into the "raft" with rebar and mesh.

The foundation with concrete footers is basically sitting on vertical concrete footers with vertical rebar supporting the heaviest sections of the slab and those are tied into the slab's horizontal rebar - basically heavy duty piers. This allows the rest of the slab to be thinner.

Did I get that right?

My confusion - Dan recommended 12"x12" concrete pillars. Erica recommended footers. What's the difference? Or Dan - did I confuse the slab construction with the vertical pillar construction to hold the tanks up?

You are exactly right . The mat slab can support the weight its basically the same thing as using a footing if done properly..


Using footings in the areas where your heavy tanks will be bring the Block up thru the floor . then pouring concrete slab around them will tie the block into the structure and give it more strength..

The benefits of a a thicker slab and building the tanks on top . you can move things around at a later date.. But you will have to pour the slab the needed thickness all over..

My thinking is it will save you on concrete cost and give you better strength where you need it..

 

[ericarenee]

You have it mostly correct. A mat footing can be one solid mat the same thickness throughout, or it can vary in depth due to loading.

A footer that is below ground is like 2 foot wide by 1 foot deep for as long as needed, like the perimeter of your house. They can also be pads, say 4 feet square and 12 inch's deep for a column to sit on.

We were arguing about which foundation is best, and either will work.

I recommended poured columns from the footer or slab going up to hold your water that is 6 foot in the air. I, persoa preference, would go with all concrete construction over block in this application. I do build bUildings and use block everyday and know that it certainly can be done with block, but in my opinion concrete would suit this application better.

yea i think we agree on what each are just disagree on which would be best for this build.. I was thinking in terms of Cost .

but i have not figured concrete for each ..

 

[karimwassef]

Ok. I'll model both:

1. A 12" slab with a 12"' skirt all around.
2. A 6" slab with a 12" skirt and 24" deep pillars (12" x 12" area) under the heavy load areas.

I'll use the volume of concrete needed for each to estimate cost.

Is there a particular concrete (2500 psi, etc...) that I should ask for?

Running the rebar up through the slab surface under the heavy loads is good on both foundations. It does limit change later, but that may be ok given the scale.

 

[karimwassef]

By "skirt", I mean the edge footer that runs all the way around. I guess this is the same as a raft or mat with footers.

Pictures should make this much clearer.

 

[Clowning_Around]

If you sunk it in the earth them you would need to consider your water table in the area treating it for hydrostatic pressure like you would for a basement wall. Granted toy would already be treating it on the positive side, you would want to consider the negative side ( n bottom similarly) as well... keeping it elevated is simplest but its not a huge leap of you wanted to recess it into the earth fully or partially. Infact if you need to remove bad soil to get down to sound material, it could save thou from having to replace with compacted fill.... As with most things in life we have options and it just depends.

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[karimwassef]

Texas clay is unforgiving on subterranean structures. We don't have basements and the classic basement design here is pier and beam. Modern construction is monolithic slab.

 

[Sharpimage]

real fast and dirty pricing for S. Florida.
12" mat slab - 12" throughout, no thinner areas- with reinforcing $12 sf
Footer 3'x12" deep $50 lf
4" slab on grade - no real weight on top $7 sf
Pad footer and pier $600 each

Hope it helps the ballpark
Dan

I am sure Texas is different, but should help compare

 

[karimwassef]

Are we talking about a pad footer and pier or just reinforcing footers?

I was just going to compare the volume of concrete needed.

 

[Sharpimage]

Are we talking about a pad footer and pier or just reinforcing footers?

I was just going to compare the volume of concrete needed.

down here, it is pad footers. the pier does not have enough sf to distribute the load.

 

[karimwassef]

Erica - what supports were you thinking under the heavy loads?
I was just thinking 2ft tall, 1ft diameter pillars under the slab... rebar in them tied to the horizontal rebar in the slab.

 

[ph_]

When our concrete would get tested from jobs it would test around 25-30 mpa or 3500-4500 psi.
I agree I would do everything out of concrete.

 

[ericarenee]

Erica - what supports were you thinking under the heavy loads?
I was just thinking 2ft tall, 1ft diameter pillars under the slab... rebar in them tied to the horizontal rebar in the slab.

I Would make the surface area of the footing larger then column . If your going 12x12 make the footing 24 in sq.10 in deep with Rebar then the colum 12 ..

Similar to the T footing in the image you posted... Hope this makes sense..

Have a Wide foot on the bottom ... Again i would have to look at the local codes and how its done in your area to give exact advise .

Here for a Pillar I did a square hole 18x18 32 inches deep.. rebar at 6 inches above 2 inches of rock.. Pour 12-14 inches of concrete.. Then the pillar or post on top that up to above grade or to height needed.. Then back fill with Rock and compact... Once you pour the slab around the pillars.. its locked into the wide footer at its base and the locked into the slab... it will NEVER MOVE ..

Prob over kill...

i would again pour footings as above.. By the way best way to dig this pillar footing holes is with a 16-18 inch auger bit... Then use concrete block and fill the cavity the vertical rebar is in... You do NOT have to fill all block cavities with mortar ...

 

[karimwassef]

ok. I was thinking of something like this... premade forms that are filled in with concrete and rebar pushing up to the slab level and tied in.

or maybe cylinder piers?

I'm graphical, so...

I think you were talking about the last on the right - pier and footing with construction with concrete block like this:

and in my search, I get ads like this claiming to solve all the problems with the methods I'm looking at (LOL):

 

[karimwassef]

Figured it's good to show the land:

Here's the plot... from the far fence edge to the left to the jump in the fence height on the right:

<a href="http://s1062.photobucket.com/user/karimwassef/media/EE82EA69-2ED5-47A3-B601-BD6ABA253856_zpsf1iggn0y.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/EE82EA69-2ED5-47A3-B601-BD6ABA253856_zpsf1iggn0y.jpg" border="0" alt=" photo EE82EA69-2ED5-47A3-B601-BD6ABA253856_zpsf1iggn0y.jpg"></a>

Here's the land on the opposite side (hill, wall, fence, trees):

<a href="http://s1062.photobucket.com/user/karimwassef/media/079CB8B6-8D3E-47C2-B06B-D34E25668243_zps4myceky3.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/079CB8B6-8D3E-47C2-B06B-D34E25668243_zps4myceky3.jpg" border="0" alt=" photo 079CB8B6-8D3E-47C2-B06B-D34E25668243_zps4myceky3.jpg"></a>

The fence sits on a retaining wall starting at the property:

<a href="http://s1062.photobucket.com/user/karimwassef/media/8FC9EBC5-9608-49F9-ADF8-DEAB9AF6B3ED_zpszfvaomqk.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/8FC9EBC5-9608-49F9-ADF8-DEAB9AF6B3ED_zpszfvaomqk.jpg" border="0" alt=" photo 8FC9EBC5-9608-49F9-ADF8-DEAB9AF6B3ED_zpszfvaomqk.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/D551A0B1-9639-45A2-B55E-24B9E48972BF_zpsggpuannf.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/D551A0B1-9639-45A2-B55E-24B9E48972BF_zpsggpuannf.jpg" border="0" alt=" photo D551A0B1-9639-45A2-B55E-24B9E48972BF_zpsggpuannf.jpg"></a>

 

[karimwassef]

I've made some changes to the design. Some better, some harsher.

First, reduced the tanks to two and incorporates two into the display. The water weight will still be focused on the back end of the tank but there's 4 columns of cinderblock there.

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/0_zpsjqldnvop.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/0_zpsjqldnvop.jpg" border="0" alt=" photo 0_zpsjqldnvop.jpg"></a>

The settling filter creates interference with the support, but it should be ok. I'll change the blocks to concrete walls tied to the slab later. This is a placeholder.

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/1_zpsvq6acpyp.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/1_zpsvq6acpyp.jpg" border="0" alt=" photo 1_zpsvq6acpyp.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/3_zpsutjts4zi.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/3_zpsutjts4zi.jpg" border="0" alt=" photo 3_zpsutjts4zi.jpg"></a>

The harsher change is the raised reservoir:

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/4_zps4zoftwo8.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/4_zps4zoftwo8.jpg" border="0" alt=" photo 4_zps4zoftwo8.jpg"></a>

It's now 9' up!!! Needs redesign but the blocks are creating a lot of weight (1400lbs) vs. the tank alone (4' x 8' x 2' = 500 gal = 4000lbs)

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/5_zpsspplpu33.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/5_zpsspplpu33.jpg" border="0" alt=" photo 5_zpsspplpu33.jpg"></a>

That may need to go steel ...

 

[Sharpimage]

Though about steel for the stands? Think it may be cost affective about this point

 

[karimwassef]

That was my last comment on the last post. I think concrete is ok for the short stubby posts. The high platform I'm thinking wood or steel.

It would be convenient to have a second floor in the back room. The room is constructed with a steel frame, so that may be a good brace supported with an elevetated 2x4 & plywood platform.

 

[Clowning_Around]

I would do all concrete even more so now... I would avoid steel given the nature of salt creep. soaking of which, you probably want to consider all your reinforcement with epoxy coating for the same reason.

In my opinion, this really does need to be designed by a professional now. I advise you work out your concept but leave the details and final drawings to the pros.


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[Clowning_Around]

Forgot a side note you mentioned lingo earlier, for when you discuss this with contractors and such. Perhaps it's habit due to the laymen use of the word cinderblock and although it may look the same it is not the same as concreteblock, which if used on your project, I highly suspect it would be the later. Just thought you might want to google it along with your other research. Gluck with your project.

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[karimwassef]

thanks for the feedback.