Cincerblock and concrete

[karimwassef]

Due to the size of my new project, I'm using the concrete floor of the slab as my sump with cinderblock sides & guides. I'm also using cinderblock for the base of the DT.

My last cinderblock base tank was in college in the 80s and it was a tiny little 180. They weren't cemented or glued together.

This is a different animal.

I will epoxy the slab before using it and I plan on using construction glue to hold the blocks in place. Those blocks that are intended to hold water, I will use hydraulic cement on to seal the cracks and then epoxy as well.

Anyone have any advice or DIY tips from actual experience doing something like this?

 

[karimwassef]

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[Desert Sea]

If I understand you correctly, your building a large sump out of concrete block that will have a concrete slab for a base. Concrete block is very porous and not a very good choice for containing water. It would need to be coated with something non-permeable and livestock friendly. Being that its a sump, maybe some type of liner would be an option.

Also depending on how much water you plan on holding, the block may need to be doweled to the floor slab with horizontal reinforcing and grouted solid. You may also want to consider using a waterstop between the floor and the block. I would suggest Type S mortar over construction adhesive for bonding the blocks together.

 

[ericarenee]

A FEW Things for a concrete tank.

1. Every 2 feet all the way around the concrete blocks Drill a 3/8 inch hole into the slab dead center of the blocks about 4-6 inches deep and put in rebar up to the height of the tank.. Do so also on each side of the corner blocks.. Put wire between each course of the blocks.. Once you have the wall build. I would use mortar designed for blocks.. Pour all the cavities full where the rebar is at.. I do not think you need to fill the blocks solid but if you have the funds it would not be a bad idea.

also use bonding blocks for the top roll and fill them with concrete as well . NOT Mortar.. Fill the bonding blocks and rebar cavity with Cement not mortar..

 

[Kadee]

Have you considered a stock tank?

 

[karimwassef]

This is a specific shape and covers 10'x13'x30" = 2,400 gallons.

I don't trust liners since I expect to be physically in this sump myself a lot. It will experience wear from walking, dragging, leaning, standing on, etc... needs the durability of a pool or jacuzzi. The irregular shape makes this harder too. There will be 10' high structures inside this sump resting of 20-30 blocks for support- all pushing against that slab.

The floor is the foundation of the building = post tension slab 12"

I plan on using the hydraulic cement to seal followed by a ~1/4" thick layer of epoxy. Why would cinderblock mortar be a better seal? If I go that route- can I skip the epoxy? I was really hoping hydraulic cement would be sufficient.

The construction is actually a combination of block and concrete walls (2" thick). The blocks are really for corners and to support heavy structures above. I've never drilled into a foundation slab but was considering asking the company would will be pouring it to add vertical rebar ties where the blocks are planned.

Only problem is if I need to make changes later.

What would be the problem with not using rebar in the sides? I realize it's not as strong but does it need that level of support? I was originally going with plywood and decided concrete and cinderblock may be cheaper and easier. If the plywood was going to be glued together, wouldn't the same construction adhesive work even better with heavy block? Why is type S better ?

I'm not asking to reject or questioning the advice ... I'm just trying to learn the limits and needs of a new medium to me.

Thank you for helping. I'm grateful for your expertise.

 

[ericarenee]

Concrete blocks are super strong stacked.. But do not take as much pressure as you think from side forces.There are adhesives for staking blocks morterless. The rebar will with the bond beams will prevent the blocks from being pushed outward from the water pressure..If the blocks were sitting on a footer then the slab poured around them would be even stronger.
either way you will have to seal the blocks

 

[karimwassef]

what's a footer? As in cut down into the slab?

let me as it this way.. if you were to build this water tight structure from scratch (slab not yet poured) to optimize for cost and strength, how would you do it?

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notice the pathway is not regular either. The flow goes through an 18" channel from under the tank into the large 5' stock tank that's acting as a sediment filter.. then to the water change section on one side and the return flow area on the other side.

 

[karimwassef]

Rechecked the height... it's 24", not 30".. so that just under 2000 gals.

With only three blocks, could I get away without the horizontal rebar?

Any advice on the cinderblock to concrete (dark gray) interface.

 

[ericarenee]

here is a image of a typical Concrete structure.. Footer depth width and reinforcement will very state to state,local building codes and design of structure above them..

The footing is below ground level with Rebar to reinforce it. Preventing separation from cracks. If you build a tank sitting on slab with no footer below the tank walls. this will put under uneven stress on that area of the slab.when this happens and it will happen. the walls will move with the expansion cracks in the slab pulling them apart causing a stress point in the wall. without reinforcement it will Fail ..


For instance when a house is built on a slab the lab has deep pockets dug out where structural supports such as load bearing walls and the entire perimeter of the exterior of the slab is deeper then the rest of the slab. this helps prevent sinking and better distributes the weight .. With the water being a DEAD Equal weight i think you need a footer below grade, then block work with Rebar. every 2 feet apart from footer thru to top of the tank.. Then pour the floor around the block walls.. now using the Concrete Colums as you have in your design will work . but my opinion is there needs to be extra rebar in the concrete blocks and all corners poured solid . Also your concrete barrier walls need to have either a channel sitting down into the poured floor or again rebar to stiffen them....

but if the barriers or baffles if you will are going to have equal pressure on each side this is less of a issue but all parameters should be as Described for a proper structural concrete wall as described above .

you can google proper above ground concrete pond or pool images for a better understand of proper construction...

the above is my opinion and i am sure others may disagree..


i cant wait to see some actually ground breaking on this project

 

[karimwassef]

So if I built a plywood tank of the same size, it would be ok. But if I just the slab that the plywood would have been sitting on, I would need to reinforce it with rebar supports?

Is the fact that this is only 24" high (usual height ~ 12-18") reduce the requirement for support?

Most of the weight will likely be under the holding tanks in the middle of the sump where the 80" of water + stack of 7 cinderblock high is pushing down in those locations. The other side has a 10 blocks high build supporting a 4' x 8' x 2' surge return tank.

 

[karimwassef]

https://www.walmart.com/ip/Drylok-E...38817&wl11=online&wl12=39921545&wl13=&veh=sem

That seals against 33ft of water. I only have 2ft

 

[Sharpimage]

You can't drill holes into a post tensioned slab, without x raying then first. It is highly dangerous. If you hit a tendon, even with a tapcon hole, the tendon will snap. I have seen tendons fly out of building 200 feet. This is what I do for a living. Dont drill holes in the slab.. but without filled cells drilled into the slab, the walls will fail. Guaranteed. Maybe it on day 1, but guarantee failure. Also 2,400 gallons is a lot of weight on a slab. A post tensioned slab is not on the ground so you may want to consult an engineer before you go any further.
Dan

 

[ericarenee]

i missed the post tension slab. and really see no reason for it.. If you put in proper Footers for the project build up the block then pour the floor around them

 

[Sharpimage]

i missed the post tension slab. and really see no reason for it.. If you put in proper Footers for the project build up the block then pour the floor around them

He said it is an existing post tensioned slab. You can't cut into a post tensioned slab. I really think you need to get a local engineer to look at what you have. I have major concerns you will threaten the structural integrity of the building. You are adding 120 psf of dead load of water alone. Just that is pushing the envelope of what the building was most likely designed to hold.

 

[Sharpimage]

I should say, I am in South Florida. And do not know construction codes for Texas, but I still have major concerns

 

[Desert Sea]

As Sharpimage noted, drilling into a post tension slab should not be attempted without x raying the slab and consulting a Structural Engineer. Severing a chord can be lethal and lead to structural failure. There are critical dimensions for hole size, distance between holes and distance to chords that must be maintained.

Is this slab an elevated slab?

You usually see post tension concrete in elevated slabs and beams, not slab on grade. If it is an elevated slab, has it been designed to carry the weight of the proposed tanks?

 

[karimwassef]

the slab doesn't exist yet. This is still in planning.

The entire building is dedicated for the tank only and the post tension slab is intended to support the weight of the tank, sump, surge, etc...

It's 25' x 48'. The tank itself is 8' x 12' x 27" (1600 gallons). The sump is 10' x 13' x 24" (2000 gallons). The first set of surge tanks are 325 gallons each x 4 = 1200 gallons. The second surge tank is 4' x 8' x 24" = 500 gallons. The last surges are a pair 1' x 4' x 5' = 300 gallons. That's not including the RODI, fresh saltwater makeup, and recycled saltwater at 300 gallons each = 900 gallons.

The slab is the foundation for a greenhouse that's 12' on the sides (15' in the middle).

I'm sure everyone has concerns... but we're still in the planning stages an can do this right.

 

[karimwassef]

and and 200 cinderblocks

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So 6500 gallons total = 54,000lbs = 27 tons

The cinderblocks are ~ 5600lbs = 2.3 tons

The greenhouse structure weighs about 4000 pounds of steel = 2 tons

so.. give or take 35 tons on a 25' x 48' = 1200 sqft

typical houses weigh between 80,000 and 160,000 pounds = 40 - 80 tons...

 

[karimwassef]

so is it impossible - I doubt it.

Does it require some planning - sure.

I appreciate all the constructive help so we can make this possible.