Existing Expansion Joints in WW Tanks

[mzaitz]

All,

We have an issue with an expansion we did on an existing tank. The original tank is about 70 ft wide and 270 ft long (plan east west) and has 3 expansion joints that run parallel to the width. The expansion of the structure which consists of another 70 ft wide and 270 ft long tank that utilizes the existing wall on the plan north. The original details show an expansion joint waterstop in foundation and walls that we are continuing in our new structure. The original details also shows a section where the original rebar has mechanical couplers so that our expansion rebar can be anchored to the original rebar. The problem is the expansion joint waterstop. Now that the foundation is exposed, it does not look like the existing waterstop was extended out to the edge (or past the edge) of the existing concrete so that we can continue it thru the expansion.

Any thoughts on how to fix this?

Thanks,

Mike

 

[HTURKAK]

Please correct me if I understand wrong ; There is an existing tank with 70 ft wide and 270 ft long , and has 3 expansion joints that run parallel to the width and the EJ provided for walls and slab foundation.

The new tank which will be expansion of the existing having dimensions similar to existing one.The original details show an expansion joint waterstop in foundation and walls that we are continuing in our new structure.

The reinforcement at the expansion joint waterstop in foundation slab or wall shall not continue. If the new tank basement will be continuous, the joint shall be CJ not EJ..

I will suggest you to construct new tank as self standing and double the longitudinal wall ..

 

[JedClampett]

HTURKAK is correct. Any fix will be difficult and is very likely to not work. It will leak from day one until the end of time.
If they continued the waterstop it would almost be worse. The extension would be all aged and hard to weld new waterstop to. And then you wouldn't have the excuse to build an indendent structure you do now.

 

[mzaitz]

All

Regrettably all of this was done before me and the issue with the missing waterstop in the existing expansion joint was not discovered until construction started and they excavated the existing footings and started laying the rebar.

I agree that building a new wall is the best option but that is also about 270 ft of new wall that was not part of the bid plus having to shift the tank out 3+ ft now that the rebar for the first pour is in place.

I have come up with a couple of ideas:

- Using a SS waterstop that is attached to the wall over the expansion joint combined with hydrophillic waterstops.

- Taking a PVC waterstop and attaching it to the wall with SS batten bars

- Using Sika polyurthane to fill the joint.

The expansion joint is only 1" wide (since there is 3 of them.

Cannot say I like any of the ideas that I have come up with. I would think there would be something out there for retrofitting existing expansion joints in water tanks.

Any other thoughts?

MIke

 

[HTURKAK]

Dear mzaitz ; contractually, this is a claim subject and you have the right for change order..you could not find the waterstop (missing ?) ..
I will suggest again building a new wall but the separation could be around 25 mm ( fix 25 mm polystyrene board on existing wall face ) not 3+ ft..

If you do one of your options and during test, you would get real headache and would not have excuse..

If I were in your shoes, I would ask for the change order, in case of refusal, just write a letter and take no responsibility and tell to the client to look this thread.

Good Luck..

 

[JoelTXCive]

Here's another idea...

You could break back the concrete about 30" inches on either side of the expansion joint waterstop and leave the rebar+couplers intact. That allows replacement of the original waterstop.

When you pour back the concrete, you install a strips of hydrophilic waterstops at your new cold joints. See attached photo.

To do this fix though, you'll have to take the existing tank out of service; which might not be feasible. And, you now have 3 joints instead of 1.

The attached photo was taken in 2002. I wasn't involved in the original project, but to my knowledge it worked.

 

[bones206]

I don't see why a retrofit WS system couldn't work. The reliability of such systems is a valid concern, but I have used them in the past and have not received any complaints (yet).

https://usa.sika.com/content/dam/dms/us01/1/SIKA Waterstops Brochure for Web.pdf

 

[JoelTXCive]

Bones' idea seems a heck of a lot cheaper and easier than mine. I like his idea a lot better.

 

[bones206]

Here is a good "tech tip" paper by another retrofit WS vendor:

https://www.jpspecialties.com/techtips002.pdf

 

[JedClampett]

This is all great, but the part that would worry me is the splice of the existing, too short, centerbulb waterstop to the piece of new centerbulb waterstop for the continuous EJ. You can use retrofit waterstop to attach walls or slabs to each other. It will work as well as it's installed.
Or am I getting the OP wrong?

 

[ATSE]

The end result of construction will be marginal at best.
Note that the existing foundation has had time to find its place and settle.
Unless the new structure is founded on piles or weathered rock, the expected large out of plane downward deflection can fail just about any waterstop type and geometry.
Not sure if it is too late, but ground improvement at the new structure edge will reduce this problem somewhat.