chunk of concrete fell off corner of slab foundation
dallasite2
| Posted in General Discussion on
Good afternoon all. This foundation was poured in 2020, less than 2 years later, a chunk of concrete fell off the slab foundation of my home (pic attached). It is located at the rear of the house, on the corner. Is this normal and just a “cosmetic” fix? I do not see any cracks or any other obvious signs inside the house. I don’t want to pay hundreds of dollars for an engineer to assess it if not necessary. I appreciate any feedback. thanks.
Replies
This is exactly why anchor bolts and hold downs generally need to be set in from corners. It's ugly but probably not a structural problem. Rebar has to be set in from concrete edges so there's not going to be any reinforcing out there so the concrete has to hold itself together. It doesn't always set perfectly. A cosmetic fix should be fine.
Thank you very much for taking the time look at this and give your feedback. attached are two pictures I took of that corner before the concrete was poured while the house was under construction. I looks like rebar is there but maybe not placed properly?
I personally would drill a couple of holes in the concrete with a masonry bit and epoxy in a couple of pieces of rebar, then fill the void, after making a temporary 2x frame around it, with polymer-modified concrete (you can get Quickcrete brand in the big box stores). For big holes you can add 3/8” stone to the mix. That will make it a structural and cosmetic repair.
Thank you for this suggestion. I was wondering what the proper way to fix this would be.
there's no issue with drilling into the concrete with the post tension cables?
I'd avoid drilling if there are post-tensioned cables in the slab. The "cosmetic" repairs with the suggested repair materials will also help avoid potential structural problems due to the p-t cables not having enough support. I'd check the area occasionally to be sure the problem hasn't progressed.
Thank you!
You only need to go in a few inches to anchor to rebar
Thank you!
Thanks for your help!
Keep it simple. It seems the slab has plenty of rough/ jagged surface to key in the repair material as to not require dowels and additional rebar. Drilling hole may also cause more damage.
Use Mapie's Planitop TG for the repair It's an excellent product and specially made for this situation.
https://www.mapei.com/us/en-us/products-and-solutions/products/detail/planitop-18-tg
Frankie
This is a great tip. Thanks Frankie!
Whenever I add a patch I slather on some concrete glue as a bonding agent. It works, it don’t hurt.
thanks calvin
Just came across your year-old post, hope your slab situation got sorted! If not, or for anyone else facing a similar issue, let's chat.
Chunks falling off ain't necessarily catastrophic, but shouldn't be the norm, esp. on such a young foundation. Could be a case of spalling - happens when water enters concrete and causes the surface to peel, pop out or flake off. Not a great look, but usually more of a cosmetic issue.
But, if in doubt, get it checked out. I know you're not down to spend big bucks on an engineer, but better safe than sorry, right? And you don't have to break the bank - check out https://www.lafayette-concrete.com/. They got affordable solutions and can give you a fair assessment of what you're dealing with.