Cincerblock and concrete
- Thread starter karimwassef
- Start date
karimwassef
Active member
I happen be rectilinear here... I'm using the blocks as corner and edge controls. Frankly, all my experience has been with blocks so they were my go to medium.
I guess concrete forms 2' high aren't hard or complicated... I was just using the blocks as guides... training wheels.
The more intense implementation of the blocks is as structural support for the raised containers. I don't know if these tall structures need cross-bracing support?
Do they need to be tied into the ceiling frame or the walls?
I guess concrete forms 2' high aren't hard or complicated... I was just using the blocks as guides... training wheels.
The more intense implementation of the blocks is as structural support for the raised containers. I don't know if these tall structures need cross-bracing support?
Do they need to be tied into the ceiling frame or the walls?
karimwassef
Active member
So the first engineering firm wants $5k... moving on to another firm
A concrete slab in TX is ~ $7/sqft in the 1000sqft space. For my 1200sqft, that's $8400
The engineering firm would basically design the slab thickness to compensate for the loading... so in some places, it may need to be twice as thick...
but for $5000, I can double the slab thickness everywhere and be ahead...
So moving on... will update as I get more feedback.
and self learning too:
http://www.blackwellpublishing.com/cooke/docs/samplechapter.pdf
https://www.wbdg.org/FFC/ARMYCOE/COETM/ARCHIVES/tm_5_809_12.pdf
http://www.engineeringtoolbox.com/simply-supported-slabs-load-capacity-d_1803.html
https://www.hunker.com/12001375/how-to-calculate-the-load-bearing-of-concrete
https://theconstructor.org/structural-engg/design-of-slab-basics/5017/
A concrete slab in TX is ~ $7/sqft in the 1000sqft space. For my 1200sqft, that's $8400
The engineering firm would basically design the slab thickness to compensate for the loading... so in some places, it may need to be twice as thick...
but for $5000, I can double the slab thickness everywhere and be ahead...
So moving on... will update as I get more feedback.
and self learning too:
http://www.blackwellpublishing.com/cooke/docs/samplechapter.pdf
https://www.wbdg.org/FFC/ARMYCOE/COETM/ARCHIVES/tm_5_809_12.pdf
http://www.engineeringtoolbox.com/simply-supported-slabs-load-capacity-d_1803.html
https://www.hunker.com/12001375/how-to-calculate-the-load-bearing-of-concrete
https://theconstructor.org/structural-engg/design-of-slab-basics/5017/
Last edited:
karimwassef
Active member
Might be good to double check some math too...
the tank is 96" x 144" x 27" = 1600 gal = 13,500 lbs over an area of 13,800 in2
so ~ 1 psi ~ 140 lb/ft2 ? Is that about right? Feels like something is missing
If I look at the tank bases, that's made up of 14 cinderblock bases = 1,600 in2, so the pressure is 8.6 psi ~ 1200 lb/ft2
This is the best reference I've found so far, by the way - https://www.wbdg.org/FFC/ARMYCOE/COETM/ARCHIVES/tm_5_809_12.pdf
the tank is 96" x 144" x 27" = 1600 gal = 13,500 lbs over an area of 13,800 in2
so ~ 1 psi ~ 140 lb/ft2 ? Is that about right? Feels like something is missing
If I look at the tank bases, that's made up of 14 cinderblock bases = 1,600 in2, so the pressure is 8.6 psi ~ 1200 lb/ft2
This is the best reference I've found so far, by the way - https://www.wbdg.org/FFC/ARMYCOE/COETM/ARCHIVES/tm_5_809_12.pdf
Last edited:
karimwassef
Active member
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/1_zpsyjgj59yo.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/1_zpsyjgj59yo.jpg" border="0" alt=" photo 1_zpsyjgj59yo.jpg"/></a>
Here's the loading distribution (no factor)
As expected, the surge tanks create the highest pressure on 6 cinderblock faces at ~ 17 psi right in the middle. The two tanks are each ~ 10psi (one is raised, the other is the DT)
The rest is relatively small in comparison.. the actual sump water is 1 psi, the garage frame is 1 psi, the concrete sump sides ~ 3psi and the concrete around the circular settling filter is ~ 1.5psi.
I may need to add more supports under the surge tanks - here's an older view but it shows the tanks:
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/2_zpsjcpwgwyh.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/2_zpsjcpwgwyh.jpg" border="0" alt=" photo 2_zpsjcpwgwyh.jpg"/></a>
here's the loading table from the reference I cited
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/0_zpsvv5zvoaz.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/0_zpsvv5zvoaz.jpg" border="0" alt=" photo 0_zpsvv5zvoaz.jpg"/></a>
Here's the loading distribution (no factor)
As expected, the surge tanks create the highest pressure on 6 cinderblock faces at ~ 17 psi right in the middle. The two tanks are each ~ 10psi (one is raised, the other is the DT)
The rest is relatively small in comparison.. the actual sump water is 1 psi, the garage frame is 1 psi, the concrete sump sides ~ 3psi and the concrete around the circular settling filter is ~ 1.5psi.
I may need to add more supports under the surge tanks - here's an older view but it shows the tanks:
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/2_zpsjcpwgwyh.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/2_zpsjcpwgwyh.jpg" border="0" alt=" photo 2_zpsjcpwgwyh.jpg"/></a>
here's the loading table from the reference I cited
<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/0_zpsvv5zvoaz.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/0_zpsvv5zvoaz.jpg" border="0" alt=" photo 0_zpsvv5zvoaz.jpg"/></a>
Last edited:
karimwassef
Active member
1000 lb/ft2 is around 7psi... so the slab overall can be 8" but the areas with the highest load will need to be reinforced... and the surge tanks would be over 20" since 17psi is ~2500 lb/ft2... definetly needs more distribution of that load!!
I'm going to draw the line at 1500 lb/ft2 ~ 10psi which is achievable with 12" thickness with 700lb in2 concrete... that means I need 10 supports for the surge tank base!! wow.
I know I'm not assuming a dead weight factor of 1.25 and I don't have the soil report to see if I need a different subgrade reaction factor... but I'm working at it. I can be a fast learner when I get silly quotes.
I'm going to draw the line at 1500 lb/ft2 ~ 10psi which is achievable with 12" thickness with 700lb in2 concrete... that means I need 10 supports for the surge tank base!! wow.
I know I'm not assuming a dead weight factor of 1.25 and I don't have the soil report to see if I need a different subgrade reaction factor... but I'm working at it. I can be a fast learner when I get silly quotes.
karimwassef
Active member
My biggest concern is the elevated cinderblock platforms, especially the one holding up the return tank. 4' x 8' x 2'
It's now over 8' in the air. Should I add a 3/4" plywood shelf every 2' up to create stability?
It's now over 8' in the air. Should I add a 3/4" plywood shelf every 2' up to create stability?
karimwassef
Active member
Another realization is that vertical storage tanks are a real issue on any slab.
In my case, these are 36" diameter and 80" tall with 325gals = 2,700lbs (1.35 tons) full.
If you use 4 cinderblocks as feet, that's an area of ~500 in2 ... that's 5 psi or 750 lb/ft2
But put two tanks on the same 4 blocks and it goes to 1500 lb/ft2 that I don't think a normal house slab could handle. It would need 6 blocks to get it to the 1000 lb/ft2 mark again.
That kind of stress is where I see the concern. The 18" of water distributed over a large area doesn't contribute much to the loading pressure. In fact, the concrete boundary made up of a stack of 3 cinderblocks creates 3x the pressure.
If nothing else, this thread has made me dig into the real critical stresses here and I can modify the design to fix it.
A painful side effect though is that adding more concrete to distribute the weight helps, but the concrete itself weighs a lot, aggravating the pressure point as it relieves it. I'll have to try a few iterations and see how to optimize.
In my case, these are 36" diameter and 80" tall with 325gals = 2,700lbs (1.35 tons) full.
If you use 4 cinderblocks as feet, that's an area of ~500 in2 ... that's 5 psi or 750 lb/ft2
But put two tanks on the same 4 blocks and it goes to 1500 lb/ft2 that I don't think a normal house slab could handle. It would need 6 blocks to get it to the 1000 lb/ft2 mark again.
That kind of stress is where I see the concern. The 18" of water distributed over a large area doesn't contribute much to the loading pressure. In fact, the concrete boundary made up of a stack of 3 cinderblocks creates 3x the pressure.
If nothing else, this thread has made me dig into the real critical stresses here and I can modify the design to fix it.
A painful side effect though is that adding more concrete to distribute the weight helps, but the concrete itself weighs a lot, aggravating the pressure point as it relieves it. I'll have to try a few iterations and see how to optimize.
Sharpimage
Member
I will cone back to say this. By the questions you ask, you should not be building this. The structure is going to fail and probably kill someone. Your cinder block structure that is glued together is going to crash. Plywood will not hold the forces you are going to inpose. You need an engineer. It will call 5 k all day long. Your structure will cost you about 30k to build from the slab to the columns. If you don't grasp that by now, I don't know what else to say.
DM and the Boys
Member
Man, it's tough listening to "helpful" advice from someone rude enough to write "Enjoy your flood"...
Just an observation...
Just an observation...
karimwassef
Active member
I'm always open to feedback but judging what I can or cannot build based on questions I ask isn't helpful. I know a lot because I ask questions and I'm willing to learn without being ashamed to ask.
I know you're trying to help and you have by asked me the right questions too. But projecting that I'm going to hurt someone without knowing what I've been able to build in the past is uncalled for, in my view.
My budget for the system is ~$50k. I'm working to bring it down to less but that's my initial goal.
My ask is that, if you can provide good technical advice on how to do things better, please do.
Opinions are easy to form and a strong function of their source and their bias. I'm looking for references, equations, industry standards, etc...
I'm always open to listening to good technical input.
karimwassef
Active member
The scope and scale of this project is large and very intimidating. I realize that this immediately drives caution and apprehension. That's a good response to unknown territory so I accept that the intent of these comments is to invite prudence. I get it and not easily offended.
No one here is out to hurt anyone else's feelings. They're really trying to help.
Sharpimage
Member
I do apologize as I was rude. I am truly trying to help, and what you are trying to accomplish is achievable, but also technically difficult. Most people can not fully grasp structural construction and what each seemingly insignificant details adds but when you add them all up it is much stronger.
To help you get on the right track, this is what I would do (after I called an engineer -got to beat the horse).
1. 12" thick mat concrete slab with 5/8" (#5) rebar at 12" on center running each way. top and bottom mat.
2. 12" square concrete (not block) columns with 4#6 reinforcing bars and #3 hoops at 8" o.c. vertically
3. 12"x12" concrete beam connecting the tops of the columns together for lateral stability.
4. for the deck, 2x6 on end, like a patio deck, with 3/4" plywood on top
5. Walls of the "sump" 8" thick reinforced concrete 24" tall. I would not use any block. #5 12" on center each way. 1 mat in the middle.
That should withstand the water and forces imposed on it. Of course everything would need waterproofing.
I would also add a waterproofing additive to the concrete. A product like Xypex or penetron. I highly doubt it is fish safe, but would help in case of any water intrusion leaks.
If you want to shoot me an pm I will give you my email and I will sketch some stuff out for you, since I was an a** earlier.
Dan
To help you get on the right track, this is what I would do (after I called an engineer -got to beat the horse).
1. 12" thick mat concrete slab with 5/8" (#5) rebar at 12" on center running each way. top and bottom mat.
2. 12" square concrete (not block) columns with 4#6 reinforcing bars and #3 hoops at 8" o.c. vertically
3. 12"x12" concrete beam connecting the tops of the columns together for lateral stability.
4. for the deck, 2x6 on end, like a patio deck, with 3/4" plywood on top
5. Walls of the "sump" 8" thick reinforced concrete 24" tall. I would not use any block. #5 12" on center each way. 1 mat in the middle.
That should withstand the water and forces imposed on it. Of course everything would need waterproofing.
I would also add a waterproofing additive to the concrete. A product like Xypex or penetron. I highly doubt it is fish safe, but would help in case of any water intrusion leaks.
If you want to shoot me an pm I will give you my email and I will sketch some stuff out for you, since I was an a** earlier.
Dan
Sharpimage
Member
Ohh, and on the post tension slab note, I think you are missing a 0. They cost payback is more like 10,000 sf not 1,000.
Clowning_Around
New member
Mixing block and concrete is not an issue, it is a common practice. Although with such a limited amount you could skip a trade and just do concrete, you could even pour the verticals art the same time as the flat work using 'hanging forms'Paying a lot of money can make things better. I agree
I'm using concrete in the hopes that it's easier and cheaper. If there are better options, I'm open to redesign.
I haven't heard any concerns on mixing block and formed concrete... why would this be?
Sent from my SM-G930P using Tapatalk
Clowning_Around
New member
One very important thing I haven't seen mentioned that you need to account for, soil bearing pressure. I know you mentioned the type of soil your accustom to in your area earlier when discussing aspects of a post tension slab but im talking compaction rating. Generally speaking if you have decent soil and only scrape off the bad topsoil before placing the concrete you are good to go but you have some considerable loading to factor. Before you place the concrete you should have a soil compaction test done by a geotechnical testing lab, they will also include in their findings any recommendations. You don't want to spend all your $$$ and not have a good base for your foundation, just think if it where to start settling on one corner more than the rest...
Sent from my SM-G930P using Tapatalk
Sent from my SM-G930P using Tapatalk
Clowning_Around
New member
Oh and 5k is alot for a small job but bigger groups don't like small jobs because its hard to justify. Try finding a one man show or similar, you can probably tell by the website. Also you can find a residential home builder and ask for a referal. If you where local to me I could shoot you a name and it bet it would be under 1k, about 800 for something like this to give you an idea of an order of magnitude number
Sent from my SM-G930P using Tapatalk
Sent from my SM-G930P using Tapatalk
karimwassef
Active member
karimwassef
Active member
That's what I meant by taking the subgrade reaction factor into account. That's one of the missing elects and I did ask the subdivision planning enginer for the soil report. If not, I was planning on a geotechnical testing lab... they need to bore into the ground to take samples and I'd need to coordinate it with the builder.
Similar threads
