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What is the recommended joint detail in long retaining walls?

What is the recommended joint detail in long retaining walls?

What is the recommended joint detail in long retaining walls?

My valuable friends

We have a habit of casting retaining walls in lengths of 36ft (12m). Between these length we usually provide large joints around 2" (5cm). We would put a water stop and a flexible fill thus forming an a joint resisting water and expansion.

Clients have often protested this detail arguing that the waterstop is OK but no need for expansion control.

What do you recommend?



RE: What is the recommended joint detail in long retaining walls?

I use something similar to your joint, except that the joint width is 1", not 2".  The water bar is located on the soil face and is secured to the wall face (I've had problems with water bar located in the centre of the wall; it's difficult to tie and keep straight).  I also pour the wall with a bit of a slope into the soil.  The wall thickness is uniform, just the forms are tilted.  This way, if there's any rotation at the base then the wall becomes more vertical rather than leans over.

I usually use a 2" reglet on the front face with foam rod to accommodate the 1" joint, a bond breaker and a 2" wide caulked joint.

I usually use 2" dia. weepers @ 4'- 6' at the base of the wall, and just above grade, with rodent screens - It's usually this item that I get flak from the client.

Actual expansion Joint distances are similar with a caulked control joint at 12' or at changes in wall height or footing depth.  Our problem is not with expansion, but contraction due to cold in winter.

RE: What is the recommended joint detail in long retaining walls?

Very cool notes DIK. Million Thanks.

Your putting the water bar at the soil face I find interesting. Never specified it that way before. I will search on how to do that.

You mentioned contraction. Does this the flexible stuff we put is a waste?.

RE: What is the recommended joint detail in long retaining walls?

Using the flat water bar with the lugs that cast into the wall allows the water bar to be placed flat and it usually stays that way. When the forms are stripped, you can see the material in place.

Our problems are often cold weather related and the main joints accommodate thermal contraction and the intermediate joints provide for shrinkage relief.  If they are working at all, it is minor (reinforcing continues through the control joint, not the expansion/contraction joint).

I usually use a two part polyurethane caulk on the outside face of the expansion/contraction joint; this is generally for appearance.  With new concrete Have to watch that curing compounds are compatible (generally are) and that temperatures are OK... had one that was done in cooler weather and it seemed to take 'forever' for the caulk to cure.

I'm not sure what you mean by flexible stuff... if this is the backer bar (ethafoam rod) then it's only purpose is to form a backing for the caulk to make sure it doesn't go further into the joint.

In lieu of the water bar, I've also used a membrane type of material, post-applied to the stripped concrete wall.  Unless you have significant water, the main purpose is to keep soil from 'washing' through the wall and staining the concrete.

RE: What is the recommended joint detail in long retaining walls?

If you are to seal for water, waterstops are OK , but not necessary if you connect old and new concrete properly. On the other hand, you need expansion joints in distances three times as much, i.e. 36m for environmental structures.See ACI 350R for information about expansion joints requirements. I beleive your clients should be so thankful of you spending lots of money for their structures to be totally unaffected by temperature!

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