Concrete crack experts

[Randy Dandy]

We are in the slow process of building a house. The attached pictures are of many cracks around the walls and at different levels. Most cracks are high to the top of the walls and some are lower. We have some cracks that follow the shape of the blocks but the ones that concern me are these in the pictures or should they ? I started this project by applying two coats of UGL Drylok to all the exterior walls from top to bottom and then the interior was applied to the lower half. Just last summer I had the walls poured full with concrete. I kept the unexposed area of concrete (the interior upper half with no drylok) wet for the next few days. Then after about two weeks I finished the rest of the interior walls with the drylok and also on top of the blocks where the anchors are placed. Is this what caused this cracking ? Can this be fixed or does it need to be ? In most place the cracks do not go all the way through to the inside but some places they do.

[ace admirer]

off hand i'd say that they are cracks caused by trapped moisture or free water freezing.

[Windy in Kansas]

Did you have anything special used in the cement/aggregate mix? I have read that some concrete products produce expansion as they cure.

[Randy Dandy]

Thanks for the help. It does make sense in a way now that even though it appeared dry on top of the blocks when I applied the UGL Drylok Im sure that it was not dry down lower and I probably sealed the remaining moisture inside and it probably froze the following winter when it tried to escape but I cant guarantee that. When the concrete was poured it was with a high water content so that it would flow properly and they told me there was a certain amount of plasticizers in it to keep it from drying out too fast.

[Beeman]

I'm guessing the top of the blocks were left uncovered and water went in and broke the blocks. Even with them filled i would be concerned about chunks just falling off. The pictures show the blocks cracked into pieces. The water might have gotten between the poured concrete and the interior surface of the block. so there is no adhesion. Cracks that follow the shape of the block are many times caused by shifting/cracking of the footers allowing the crack to form.

[Darren]

Normally you use plasticizer (extra cost) to keep the water content low. I'm wondering if the contractor just added extra water to make their job easier. That's one of the most common mistakes. You can also ask for silica fume to be added to improve flowability. Silica fume also has the property of making concrete less permeable.

Did you use place vertical rebar in some of the cells?

The only fix I know of that will fix any structural problems is epoxy injection. I saw a 500' cooling tower that was damaged by a tornado fixed that way. Unfortunately it's specialty work. I recently talked to a contractor about sealing a block wall that had been grouted to make it waterproof. It didn't.

[Windy in Kansas]

I do have one thought for a fix but it won't be cheap. Sand blast the coating off and then use a surface bonding product on the block before they do come apart. Quickrete makes one called Quikwall. http://www.quikrete.com/ProductLines...dingCement.asp

You might consider contacting the company to see if the Drylok would even have to be removed but I'm guessing it would.

Best wishes.

[rambler]

Did you place rebar horizontal & vertical in those walls?

In an old foundation, oh well it's old & cracks & settles.

In a new foundation, I feel for you - that does not look like a good thing to build upon. I donno. Without rebar, think a couple good linebackers could bring it down right now.......

Is that rust stain under the arch, or?

--->Paul

[agmantoo]

Use the drystack product here and put the problem behind you. I have used a lot of this product!
http://www.resarch.com/bonsalamerica...y/SUREWALL.PDF

[doohap]

Originally Posted by rambler

Did you place rebar horizontal & vertical in those walls?

In an old foundation, oh well it's old & cracks & settles.

In a new foundation, I feel for you - that does not look like a good thing to build upon. I donno. Without rebar, think a couple good linebackers could bring it down right now.......

Is that rust stain under the arch, or?

--->Paul

Gotta' agree with Paul here. If there's no rebar in those blocks, I'd be afraid ...

Foundation problems are no fun!

Peace,
doohap

[SteveO]

Morning All,
All little more info please
How often do you have rebar verticle.
How often do you have bond beams and what did you put in them as far as rebar
Did you use Durawall a 9 gauge wire ladder looking material in the horizontal.
Is the whole wall completely filled with concrete and what was the strength of the mix?
Is there rebar in the verticle under the lintel?

Sorry about the questions
and lastly were the tops of the cells open all the time to the weather could they have had water in them? And how long after you grouted did it get cold.

I will check with my supplier about your paint.

Steve

[Micheal]

Ohh boy, the best idea I would offer is - to replace any cracked block as it ain't gonna get any better. A cracked building block is just a problem in waiting no matter how it's patched or held together.
Sorry.........

[Beeman]

Another thought about the cracks that follow the joints of the block. I noticed you live in TN. In E TN we have a lot of limestone rock and a lot of movement. Were there any rocks in the footers, Possibly some you poured around? Cracked footers and cracked block walls are very common especially with rocks in the footers or basically anywhere near or under the footers. I've seen the footers crack from rocks shortly after the walls were built. How deep are your footers?

[Randy Dandy]

Thanks again for all the help. There is no rebar in the blocks. I ordered a higher grade of concrete when I ordered...I want to say 4000 psi but Im not sure. The walls are filled completely. I had another well experienced person look at the walls this weekend and agrees that the cracks are not good by any means. I will consider paying someone to fix the cracks but at this point and time I believe we will have to seriously consider tear down and remove and start over. The wife and I are seriously considering a manufactured or modular home at this time. This problem with the cracks is a direct result of someone (myself) trying to save money by doing the job myself and would have been better off leaving it to the professionals who do it for a living. There are certain jobs throughout my life that I can attempt but this will never be one again. Sorry for the whine and cry. Thanks again for your help and concern. Im suppose to meet with another individual tomorrow evening so he can look at it. It might be quite some time before I get a chance to get on here and reply.

[GoldenCityMuse]

Hey Randy,

Sorry to see & hear your problem. No rebar at all is a serious problem. You should have had 3/8 min in each core before you filled it with concrete. Concrete's strength is only ion compression, it is quite weak in tension, which is what the steel is used for.

Concrete cures by a chemical reaction, not by drying out and hardening, & it takes at least 30 days.

If too much water is added to the mix, it will greatly degrade the strength of the concrete. SO having extra strong mix was probably negated by too much water.

I'm afraid you will need to tear it down, it has no strength to support a building. I do not recommend trying to patch it, you will always be doing repairs and being aggravated.

Let us know what happens.

[T-Bone 369]

In the third picture the lentel is incorrectly placed. The angle iron should be back to back not face to face so that the only part of the iron exposed will be the bottoms of the angles in the door opening. As they are now they will catch water and you can see the results - water penatration in the block directly under the end of the lentel and freeze/thawing cycles causing cracking. On top of that the angle iron will eventually rust and expand causing more cracking in the course on top of the lentel, and in the longer term it will fail and collapse. Sorry for the bad news. Trust me it is much easier to fix before you build than later.

[Randy Dandy]

Thanks again for all the help. From what information we have gathered thus far it does look like we will need to tear down and start over. I dont believe we will be able to trust the structural value from this point forward.