Retaining wall options

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Old 09-09-08, 02:31 PM
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Retaining wall options

I am in process of deciding on which block (retaining) to use on my project. Keystone (Compact II) or Alan Block (AB Classic) .
project region - So California.
distance between the front of the wall and property line - 24"
not sure if it is considered a surcharge but there is a wooden fence (with concrete footings) right on the property line and a 4' concrete slab by the neighbor's house so some of the wight of the house and the concrete will be transferring to the wall I assume.
It will be a 120+ ft. wall about 30"+ tall with 10" gravel footing and 4" drain pipe (maybe doubled) below the grade.
I have two main concerns (since the price of the block is almost the same).
1. Fluorescence - Too many time I pass a retain wall and it's just blaring with fluorescence. Which one of two i am looking at is more prone to it and how to avoid it.
2. Which of the walls will require less of the setback?
I realize that installing a reinforcement grid material would be the best, but there is just no space for it. Should I still add a foot behind my wall for a good measure or?

Thanks for all your help!
 
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Old 09-09-08, 04:11 PM
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Retaining wall options

The design and construction of a segmental retaining wall (SRW) is about the same, whether is a wall using Allan Block, Anchor Wall Systems, Keystone or Versalok is essentially the same. Each has some unique advantages, which may be desireable for some walls, but for such a small wall, it is just a matter of cost and appearance preferences.

Your wall is very low, so geogrid should not be necessary, unless you have some very unusual conditions. If the wall was 40' high, that would be a different question.

All SRW block are usually locally manufactured and use the same local raw materials (there are no real manufacturing techniques), so efflorescence is dependent on the quality of the backfill and drain tile function.

What is the relative height of the neighbors house above the wall and the distance away?

What do you mean by "set-back"? Is that the distance from the property line? Each wall system have a "batter" of the wall face, dependent upon which shape is selected.

Adding a foot behind the wall do little to change things.

Dick
 
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Old 09-09-08, 09:40 PM
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thanks a lot

thanks a lot for your reply!

I was thinking to add a water barrier behind my wall before backfilling, something like visquin or maybe drylock on the back of the blocks?
The neighbor's house will be about 6" (inches ) above the top of my wall, but only 4' (feet) away. Fortunately the runoff from his roof (unlike mine) is directed in the 90 degrees to my wall so hopefully less water.
by setback I meant the horizontal distance between the face of the bottom block to the face of the top block, since I have very little room to play with, it is a concern.
By adding a foot behind the wall i meant a foot of geogrid material to stabilize the backfill behind the wall. But you already answered that - i guess I don't need it. I always tend to overbuild
I found a little cheaper (hopefully) block from Keystone - Legacy Block - it is 3" shorter in depth then Compact II and about half the price. If i install the first row 4" below the grade my wall above the grade will come to 32" which is I guess in acceptable by Keystone standards. The question is - am I loosing any wall strength by using a smaller block or I am I gaining anything by those extra 3" of backfill?
thanks again!
 
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Old 09-16-08, 09:02 AM
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Exclamation got it now - now what?

I just got a delivery of 500 Legacy (Keystone) block. Some of them look perfect - just like the ones at the yard, but some have fairly deep (forming i assume) cracks going about the middle of the block across. I did not try hitting it with the sledge hammer or anything but I am concerned and wanted to ask someone's opinion before i start calling the yard that sold them to me or start installing the blocks.

Thanks for your help!
 
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Old 09-16-08, 11:06 AM
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finally got a hold of the yard, they say it's normal drying cracks =.... Peeping On U2 not sure if I should trust the people that sold it to me. But i already have another question I have a 110 ft wall to build, only about a quarter of it is going to be in front of my gate in the front yard the rest of it in the back. I did not want to start from the front because I'd have to live for a long time without the gate that way. Can I start from the middle of the wall or I need to make the first run of the blocks the whole way - front to back. I have no idea what I am doing if that isd not obvious yet.
 
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Old 09-16-08, 11:12 AM
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Slump cracking. Bad case of it, but shouldn't be a problem.
 
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Old 09-16-08, 11:25 AM
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You generally start at the "tight" end. That is, if the wall ends against something that can't be moved or adjusted, like a foundation, you start there. If the ends are "loose" it doesn't really matter.
 
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Old 09-16-08, 12:38 PM
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Thanks a lot!

at least sometime i get to hear what i want to hear
So I can start laying my gravel (btw. both ends are loose) in the middle of my wall. I still have some remnant of the old wooden retaining wall holding up the soil at that point on to the front yard so i wanted to preserve it for now, otherwise I'd have a complete exposure and I don't want that.
When I am almost done with my 1/2 of the wall I will start with the rest of it and connect drain piing with sleeves - rite?
 
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