Concrete/CMU Crack Causes

[mmmbmf]

I have a situation where the interface of a concrete tie column and CMU has cracked. Our typical detail calls for the CMU face be be broken out so the concrete will pour into every other cell. Can someone give me their opinion as to what is causing this? See Photo

 

[mmmbmf]

Here is another picture

 

[JAE]

Looks to me like concrete and/or CMU shrinkage. Note that the cracking appears to diminish just below the bottom of your concrete lintel beam.
So if the lintel beam has any significant length, and the concrete shrinks some, it would pull away from the CMU wall beyond the opening.

I can't believe that a beam that deep would also flex downward much to cause cracking but if the shoring was removed too early it might have also rotated at the "fixed" ends - which would cause similar cracking.

 

[mmmbmf]

Thank you JAE for your opinion. I respect your judgement and appreciate your time responding to my question.

 

[Tomfh]

Agree. Shrinkage/flexure cracking. Is the concrete tied to the block work?

 

[mmmbmf]

Tomfh. Yes it is. I have been told to chamfer the tie column vertical edge next to the block work and possibly have the crack form there. I question if I should be tying the pour together by breaking out the face of the CMU. What method would be more common at junctions like this to address shrinkage/temp cracking? Or perhaps other methods?

 

[Tomfh]

If it’s tied together I wouldn’t be too fussed.

Yes you can open the blocks and make the reinforcement continuous to make it somewhat monolithic, however it can still crack. Even solid concrete will often crack.

 

[mmmbmf]

Thank all of you for your help. Hope you have a great weekend.