View Full Version : Local wall failure (More Pics )

07-19-2007, 10:18 PM
Okey everyone i stopped by this job this evening and took some more pics. Look at the grid placement, and the un compacted back fill. Also what kind of block is this?

07-19-2007, 10:24 PM
Friggin' scary!!!

Bill Davis
07-19-2007, 10:33 PM
Block is made by a company called rockwood. The blocks interlock without the use of pins. They work real well if installed correctly. A local contractor here had a large wall fail due to incorrect backfill material also. Seaballast is the best kind of gravel to use to backfill and fill the voids in the blocks. Using shale, SB2, or any material with clay in it due to the fact they do not offer any drainage. Hope this helps

07-19-2007, 10:49 PM
My sales rep from ab bidded on this job and said it was Keystone. I have never seen a Keystone block is it close to what you are talking about?

07-20-2007, 09:42 PM
Is it possible they ARE using Keystone and ARE NOT using the pins? That could play a huge role in this failure.

Could it be?

[Edit] Nevermind...the closeup of the block does not resemble Keystone and there are no pin holes.

07-20-2007, 10:17 PM
I've never seen a keystone block to even comment on it.

07-21-2007, 01:42 AM
I have used both Rockwood and Keystone.

The picture is of Rockwood.

07-21-2007, 01:38 PM
Here ya go!

07-21-2007, 05:20 PM
Here ya go!

Okey, so what kind is your pic because it is different than my pic.

07-21-2007, 05:40 PM
The block pictured in championls post is a keystone Standard Unit, they weigh right at 100 pounds. We use them here but we mostly use the keystone compact unit. Keystone makes a great block and we have a great supplier, we are also a distributor for Keystone.

07-21-2007, 06:32 PM
I believe in summary, even though most of us agree we don't like the choice of backfill material, it wasn't the soil backfill that caused the failure. It appears to have been the mechanical connection between the grid and the blocks themselves.

Looking closer at the design of the block, the cheesy back lip and the sort of dip in the middle... which presumably helps the blocks 'nest' together as they are stacked, do not combine to produce adequate holding power when the blocks are stacked that high.

Assuming the contractor followed the manufacturer's instructions while stacking and gridding....then...it could be said the blocks should not be rated for a structure that high. Or, anywhere near it.

This is all speculation of course.

07-21-2007, 11:46 PM
Even if they used Geo-Grid, the grid could easily pull out and/or cause the back lip not to interlock with the block below it. That block just looks bad for the height they are trying to accomplish.

07-22-2007, 05:15 PM
I agree with both of you about the block. But what about the grid being there up to the face of block then filled with stone. Dont you think that weight would of held. I think maybe the batter being so vertical that every course should of been gridded at that height.

07-22-2007, 08:52 PM
geez that guy has every color of block they probably sell in that wall.

07-23-2007, 10:11 PM
That's a base keystone block. The main blocks are shorter.

I feel the small lip on the back of the blocks in the photos are way too small. It's barely 5 inches wide. The drainage aggregate's weight just kept sliding down and heaving the wall forward. Judging by the pics, it seems like they just stacked the stone, added some grid and use native soil to backfill.

07-23-2007, 10:18 PM
Yes, my sales rep from ab bidded the block to the contractor but of course didnt get it. She said it was Keystone that got the contract, but she is 100 miles away and hasen't seen the job either. Ive seen a far amount of block in my time and even if i didnt care for them i could still figure how they went togeather. These things just puzzled me. Also my rep said they speced a vertical wall no batter to slight , ab bailed out and said 6 degree or nothing.

07-23-2007, 11:34 PM
Thats not Keystone. Both the standard and compac units both use pins.

Looks like a bunch of clay in that soil, without proper drainage or grid. Would like to meet the engineer that signed off on that one.

07-24-2007, 04:44 AM
The keystone block is in the photo on page 1 (not the wall).

07-29-2007, 03:42 PM

07-29-2007, 03:44 PM