Selecting the right expansion board for an expansion joint

[GeotechRic]

Here is the situation, due to the project requirements I need an expansion board that is flexible and excellent as a water seal. The board would be used for an expansion joint between a concrete wall and a wall cap in order to prevent water from infiltrating behind the wall and freezing and thereby creating problems. Basically we need something better than typical wood/plastic expansion boards. Any suggestions?

Also what would be the procedure to install these? Would a sealant be also needed on top of the board to ensure a better seal?

 

[37ed]

Good one,

The only thing I can think of is PVC water stop,but that is not going to help much with expansion.
I have used selfleveling sealants in slab joints where I have expansion board,and it has worked well.The only trouble found is to make sure contractor does the job carefully.

 

[37ed]

A better idea here,maybe.
what about a drainage design to remove the water from behind the wall?

 

[GeotechRic]

There is already a drainage system designed for the area behind the wall but we want to ensure that no water will get in there in the first place. I was thinking of placing a rubber or flexible foam expansion board in the joint between the wall cap and wall with a backer rod and then a 1/2" cover of joint sealant in the expansion joint.

The waterstops (PVC) will be used along the other construction/expansion joint but not for the expansion joint along the wall cap- wall connection.

 

[jike]

What is the wall cap constructed of?

 

[37ed]

I think by what you have said, you have the right idea.
Is the cap PRECAST,CAST IN PLACE,or what?
Also I am looking at some data on foam expansion,will get back to you on pressure,and life span.

 

[GeotechRic]

Wall cap is cast-in place and will connect with wall on one side and the other end with an exposed rock face.

37ed that would be good info to have. Feel free to get back to me at anytime. You might want to check out a product called Ceramar by W.R. Meadows.

 

[SlideRuleEra]

Maybe a bentonite based product could be used. Here is a link for general information. Perhaps you can contact the manufacturer for a recommendation

http://www.cetco.com/bmg/home.htm

In my opinion, bentonite waterproofing panels and water stop are the best available - and this is for applications such as cast-in-place underground industrial structures (water table at ground level) and electric utility cooling tower basins.

http://www.SlideRuleEra.net

 

[GeotechRic]

Problem is the bentonite seals are for non-moving joints therefore do not allow for much flexibility. Also they are not as resistant to chemicals, oil, etc.

 

[37ed]

Have you looked at WEBAC 157 or any of there products

 

[GeotechRic]

Sounds like an option definitely but I would not use it by itself in the concrete joint.

I think it would be very effective if placed over the backer rod and expansion board as the first layer of defense against moisture.

 

[miecz]

Why can't you use a PVC with a center bulb?

 

[GeotechRic]

PVC waterstops are going to used along with an expansion board/joint sealant system in the other expansion joints along the wall.

PVC water stops are definitely an option but maybe a good quality, flexible expansion board/joint sealant system can cut it for the wall cap/wall connection.