Cracked cement block foundation

[austin]

I discovered a vertical crack above grade and chiseled it out to see what was going on. Digging down revealed a couple of stepped hairline cracks, but nearly as bad as what you see above grade. The first photo shows the top of the foundation from inside the house. You can see rigid polystyrene on the inside wall between the blocks and the 2x4 framing. The second photo shows 9 rows of concrete blocks. From top to bottom:
Row 1: no mortar (vertical)
Row 2: cracked block (vertical)
Row 3: no mortar (vertical)
Row 4: cracked block (vertical)
Row 5: no mortar (vertical)
Row 6: cracked block (vertical)
Row 7: no mortar (vertical)
Row 8: no mortar (vertical and horizontal), but not cracked.

I thought I would fill the cracks with mortar from the outside, apply a membrane and 2" rigid polystyrene on the outside, then fill up the cell with cement from the inside all the way down to the footing. But the space is pretty tight and I don't think I could tap it down well enough so there wouldn't be a lot of air pockets. Any advice?

[pushkins]

You really need first to address the issue "why is it cracking" from your first photo it looks like the foundation is settling on this corner.
If it is foundation movement then nothing you do cosmetically will solve the problem in either the short term or long term.
Are there downspouts in the area, what is the grading like ? again from the photo it looks like the grade flows to the house, this needs to be away from the home.

[austin]

I think the crack has been there for a long time, probably due to initial settling of the house. Another possibility is that it occurred when the next door neighbor dynamited out granite to build his basement for new construction. There are no downspouts in this area. This is a corner of the front entrance that juts out from the front of the house. There are 10 foot extensions on the downspouts located on the other four corners of the house. The ground slopes away from the house (you can't see that because I dug down a foot or so to see what was going on below grade). The basement is very dry and there are no musty odors. The back fill is sand. Basically, I think the foundation is stable, but time will tell. Nights here are already below freezing, but the forecast is for a few warm days this week so I want to at least get something into that crack now. The Home Depot guy sold me a couple of tubes of "Quikrete Concrete Repair," which he said would be better than using mortar. I was looking for Epoxy Crack Filler, but none of the stores here carry it.

[austin]

There are two other possible explanations for settling at that corner. There had previously been a retaining wall 10' out from the foundation built of old railway ties that were anchored via a chain attached to a bolt set in the foundation wall below grade, but in line with the vertical crack seen in the photo. The retaining wall was pulled apart with a mechanical shovel, so there could have been a lot of tension on that chain (that no one knew was there). There other possibility is that granite boulders (from the neighbor's blasted out basement) were used to replace the retaining wall. They're all in a line parallel to the face of the foundation that you see in the photo, about 10' out. Except around that corner, they're a lot closer to the foundation - to within 2 to 3 feet. Perhaps the weight of the boulder around that corner caused some settling. This work was done about 3 years ago.

[pushkins]

I don't think the "placing" of the boulders was/is an issue BUT the pulling apart of the old all with chains attached to it would be VERY high on my % chart of reasons.
The tube caulk (mortar repair) that you have from Home Depot probably would be the best repair for at least now, it will remain flexible and allow contraction over the coming months, it will also be a good gage if any further movement occurs.

[austin]

Yeah, I could hardly believe my eyes when I dug down the side of the foundation and found that chain bolted to a cinder block. I cut the chain with a bolt cutter. A stake in the ground would have been a better idea. What was he thinking? Anyway, should I try and remove the bolt from the cinder block and patch the hole, or just leave it there?

[austin]

I found a tube of Sikadur Sika "Crack Fix Structural Epoxy." There are no "A" and "B" products to mix, just one product in the tube. Which product would you go with, that or the Quikrete Concrete Repair (acrylic formula) I got at Home Depot? Both products are applied using a caulking gun. Or, I could use one product in one section of the crack, and the other product in another section of the crack and see next year which one worked best.

[pushkins]

The structural epoxy is an agent that will try to adhere the two surfaces together, if your sure there is no more movement of the wall then this would be the product to use. Beware thought,if there is further movement and you have used an epoxy it often will cause greater damage to the cinder blocks at least with the flexible crack repair it's a caulk based product and has a tremendous amount of give.