Honeycomb appearance on blockwork wall

[Uprising]

Hi All,

We have undertaken a visual inspection of a carpark structure, and a blockwork retaining wall is showing signs of moisture ingress, efflorescence and what appears to be a honeycomb appearance on some of the blocks.

Any idea what could have caused this and whether it needs repairing or further testing?

Cheers,
Luke

 

[Ron]

Luke...it looks like the masonry is scaling in isolated locations. This can be caused by wetting and drying effects and by freeze-thaw issues.

 

[Uprising]

Thanks Ron, this blockwork appears to be undergoing wetting and drying, no freeze-thaw issues in this area.

 

[hokie66]

Yes, alternate wetting and drying can cause that. Rising damp is also likely. If it had any, the external membrane has failed.

 

[dhengr]

Uprising:
I certainly would do something about the water penetrating the conc. blk. wall from the outside, that seems to be causing a good share of the problem. Waterproof the exterior of the wall. An exterior drain tile system. Improve the surface grading to improve drainage away from the bldg. I would want to know much more about the quality and integrity of the blk., because the problem seems much more severe on some blocks than on others. It would be interesting to have a good testing lab comment on the various levels of blk. degradation, maybe take a few different interior face shells into the lab for testing. The movement of water from the outside to the inside is moving minerals and salts to the inside, and as the water evaporates and the minerals crystallize and expand in volume just under the interior surface of the blk., they expand and cause spalling at the surface of the blk.

 

[Uprising]

Thanks for the comments.

I was onsite yesterday, and you are correct that the surface of the block is spalling off, it was very flaky, and it was just leaving behind and exposing the block aggregate.

Based on the original drawings, no external membrance was specified, and hokie66 you right in saying that if there was one it had failed by now. There is a paved road behind the retaining wall that appears to be sloping away, however, the landscaped podium level drainage (which is regularly watered) appears to outlet right behind the retaining wall, which is the likely the source of moisture.

http://files.engineering.com/getfil...-9654-bf6a9633d019&file=Blockwork_Section.JPG

http://files.engineering.com/getfil...46-afd0-9abb9bb284df&file=20170525_142446.jpg

http://files.engineering.com/getfil...f5-a30d-1b675c64afa2&file=20170525_142628.jpg

 

[hokie66]

I have seen that many times. Unless you can now install a membrane on the outside, the wall will continue to deteriorate.