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Discussion Starter · #1 ·
Hi, good day. The 7' retaining wall around my house and garden is cracking. The house is on a small rise above the split in the road. The retaining wall is basically holding all the soil back, so I'm quite concerned. The houses here are built on saprolite, what we call rotten rock, so it's not that stable. The wall, originally built, in 1974 is made of breeze block and every 6 feet or so they've added a buttress(?) to support it. I live in the Caribbean and finding qualified people for something like this is VERY difficult (the good ones are all building million-dollar homes :)). We've been told by many to chip out a groove and refill with cement. Can it be that easy? Won't it crack again, with all this weight? The crack that concerns me most is about 1-2".

These two photos show the biggest crack, the one I'm concerned with.
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This one below isn't so bad. Thought the refill method could work.

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This one also doesn't seem so bad.

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I'd appreciate any suggestions to make this strong again.
 

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This will be a job for a retaining wall contractor. You have to find one sooner better than later, because it looks like 2 wall sections are separating.
The top picture shows a drain opening - does it ever leak water?
 

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Discussion Starter · #3 ·
This will be a job for a retaining wall contractor. You have to find one sooner better than later, because it looks like 2 wall sections are separating.
The top picture shows a drain opening - does it ever leak water?
dj3, thanks for replying.
Oh boy, I have never heard of a retaining wall contractor on island. Lot's of contractors but none that I know with this speciality. These walls were built by an of island island company hired to do this subdivision years ago. I have never see water coming out of the drain openings. There are approx 16 drain opening like this down the entire wall. Can't remember one of them releasing water.
 

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I'm by no means am expert but when I had a similar problem I had to rip it all out and relay the block, in your case pouring a new wall. But there may be solutions involving sinking vertical I beams to stop them from moving. Maybe even Kevlar straps. A basement contractor probably has solutions.
 

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dj3, thanks for replying.
Oh boy, I have never heard of a retaining wall contractor on island. Lot's of contractors but none that I know with this speciality. These walls were built by an of island island company hired to do this subdivision years ago. I have never see water coming out of the drain openings. There are approx 16 drain opening like this down the entire wall. Can't remember one of them releasing water.
Ask around. Start with concrete guys.
With plenty of building among hills and mountains, there must be some contractors specializing in retaining walls.
If not, contact one in the USA who will be willing to advise?
I've seen retaining walls that have been fixed by adding supports, adding rebars. and in some cases, they were able to align and plumb leaning sections.
Demolish and build new is last resort.
 

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I would suspect the 16 drains are blocked. Water behind the wall is surely the culprit. Patching the blocks is just temporary. Get the water out from behind and the cracks will stabilize as they are.
 

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Anyone that builds seawalls?
 

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Discussion Starter · #9 ·
I would suspect the 16 drains are blocked. Water behind the wall is surely the culprit. Patching the blocks is just temporary. Get the water out from behind and the cracks will stabilize as they are.
We've just been through a 4 month dry season, would water still be trapped behind there? There is about 4 feet of soil and rock above most of the of the drains. Maybe place new drains higher up?
 

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If the soldier beams, AKA buttresses, are concrete, what I would do in what I assume to be your situation (disclaimer: as a PE I can't say how well it will work):

Where the crack by the soldier beam is, drill a series of 1/2" diameter holes 4" deep into the side of the soldier beam, 2" from the front face of the wall, every foot along the height, starting 6" down from top. If you can get epoxy rebar anchor adhesive material or non-shrink grout and some 8" long pieces of #3 rebar, that would be the best. 1/2" wedge anchors that are 8" long, would be the next best thing. If neither of those are available, #4 rebar, pounded in to the holes would be ok. Once the rebar or anchors are in place, form up for concrete 6" out from the soldier beam along the wall, out to the face of the soldier beam, and up about half the height of the wall. Mix and pour concrete into what you have formed up, and insert a rebar or wedge anchor halfway down into the concrete in the middle. Form it the rest of the way to the top the same way, and finish pouring concrete to the top.

This is based on some assumptions of what is available to you, from my limited observation of construction in Haiti 13 years ago, so you may have better materials and techniques available than what I saw at that time and place.
 

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Discussion Starter · #12 ·
Where the crack by the soldier beam is, drill a series of 1/2" diameter holes 4" deep into the side of the soldier beam, 2" from the front face of the wall, every foot along the height, starting 6" down from top. If you can get epoxy rebar anchor adhesive material or non-shrink grout and some 8" long pieces of #3 rebar, that would be the best. 1/2" wedge anchors that are 8" long, would be the next best thing. If neither of those are available, #4 rebar, pounded in to the holes would be ok. Once the rebar or anchors are in place, form up for concrete 6" out from the soldier beam along the wall, out to the face of the soldier beam, and up about half the height of the wall.
Good day HotRodx10,

Thank you for the reply and your advice.

Luckily we have access to rebar in all sizes. Bare with me, I have a few questions. One of the cracks is about 5" from the soldier beam, so would it be o.k. to use 10" of rebar so they would stick out 6"? If the rebar sticks out 6" would a 4" hole in the soldier beam still be sufficient? Or should we make it 6" into the soldier beam, making the rebar 12" for a total of 6" in and 6" out? I understand that then the form would have to extend 8" out from the soldier beam.

Mix and pour concrete into what you have formed up, and insert a rebar or wedge anchor halfway down into the concrete in the middle. Form it the rest of the way to the top the same way, and finish pouring concrete to the top.
Again, I'm sorry to take up more of your time but I have a number of questions about the last part. This is done in two steps as opposed to a continuous pour? Please, so I understand, may I know the reason for this? Also, if the reason for the rebar inserted after the first pour is to tie the top and bottom pours together, would it not be stronger to take a piece of rebar, place it vertically and wire it to the horizontal rebar, so that there is a continuous tie-in to the top and bottom that would distribute the load more evenly?

I just want to double-check, will this epoxy work?
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Thank you for your time. I look forward to hearing from you.
 

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This is done in two steps as opposed to a continuous pour? Please, so I understand, may I know the reason for this?
It would be done for 2 reasons. 1) Concrete dropped 7' may segregate (cement separates from the rocks), and 2) the fluid pressure on the formwork at the bottom with 7' of concrete above it can be fairly significant, more than twice what it would be filled with water.
Also, if the reason for the rebar inserted after the first pour is to tie the top and bottom pours together, would it not be stronger to take a piece of rebar, place it vertically and wire it to the horizontal rebar, so that there is a continuous tie-in to the top and bottom that would distribute the load more evenly?
That would certainly be better.
so would it be o.k. to use 10" of rebar so they would stick out 6"? If the rebar sticks out 6" would a 4" hole in the soldier beam still be sufficient? Or should we make it 6" into the soldier beam, making the rebar 12" for a total of 6" in and 6" out? I understand that then the form would have to extend 8" out from the soldier beam.
With the epoxy done properly, 4" embedment should be enough, but 6" wouldn't hurt.
I just want to double-check, will this epoxy work?
Yeah, that would be the stuff. A couple of very important tips for the epoxy: 1) Be sure the holes really clean - no dust; no water. 2) Be sure the 2 parts of the epoxy get thoroughly mixed.

Bigger rebar wouldn't hurt, especially where the crack is further away from the soldier beam. For that one, I'd bump up to #6 rebar and embed it 6" if you can.
 

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Discussion Starter · #14 ·
It would be done for 2 reasons. 1) Concrete dropped 7' may segregate (cement separates from the rocks), and 2) the fluid pressure on the formwork at the bottom with 7' of concrete above it can be fairly significant, more than twice what it would be filled with water.
Thank you for answering all off these questions. This all makes perfect sense. We now have a clear picture of what should be done. The only question remaining is how long should the first pour be allowed to harden before the second pour is added?
 

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This may be an option to reduce the pressure on that wall.
you will have to dig the dirt out from behind the wall, fill it in, and every so often drop down some galvanized or otherwise dirt / water proofed mesh material (plastic might work?)
look up on youtube "mechanically reinforced earth" some people made videos about it to show the process.

Good luck!!
 

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This may be an option to reduce the pressure on that wall.
you will have to dig the dirt out from behind the wall, fill it in, and every so often drop down some galvanized or otherwise dirt / water proofed mesh material (plastic might work?)
look up on youtube "mechanically reinforced earth" some people made videos about it to show the process.

Good luck!!
For MSE, it takes more than just haphazardly throwing some plastic mesh in the dirt. You need real geogrid and some kind of facing element, even if it's just wrapping the geogrid back into the backfill.

If the OP wants to go take it to that level, best to replace the wall, or add lagging to span across behind the soldier beams.
 
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