Hey anons, chiming in for a concrete assist
>some cuban guys did the neighbor’s driveway
>shit is cash, beautiful to be frank
>hire them to pour a slab for an exposed patio
>they do an excellent job
>looks a little discolored in one spot, pay it no mind after looking up that it would go away, otherwise fantastic
So I pay the man. Few days later
>spot is still discolored
>get closer now that I can walk on the slab
>”discoloration” is in fact low spots (pic related, no more than an 1/8” deep. ignore my lewd footprint)
>concrete guy comes to remove the forms
>he apologizes, says he’ll resurface it and it’ll look great
>sounds good
>he leaves, I never hear from him again and he ghosts me
>lesson_learned.mp4
Anyway I’m racking my head how to fix it. Many sources say to tear the offending part out and repour because anything else is stupid, others say that is retarded and to just resurface or epoxy the entire slab, and others say to grind the surface of the whole slab down to the low spot. This thing is 500 sqft for reference.
I’m planning to get some trowel grade pre-mixed resurfacer (quikrete re-cap) and trowel it in trying to match the surrounding level and broom finish, then paint if it looks too off-color. Is this just a waste of time? If so, any other suggestions?

>>2920762 (OP)
My driveway is just rocks.
My other neighbour paid a fortune and put in interlocking bricks. Some of them sank, but he pulled them up, put sand under them, and they were fine.
This guy from work came home and there was a huge crack, like 1/2" in the corner. He cut it out with a saw, filled it with concrete, broomed it, and it looks mint with “control joints” where new meets old… which should have been in there from the beginning.

>>2920762 (OP)
My book on Masonry by Time-Life Books from 1976 says it's either scaling or spalling. My guess is it's scaling due to too much water or it got hit with a freeze before it could cure. My camera is shit, so I'm going to have to paraphrase. The "fix" page says concrete surfaces can't be repaired by more concrete, only grout, mortar, sand-cement-epoxy compounds, pre-mixed cement or latex compounds that come in a can or cartridge can bond well to a concrete surface. For spalling, it says to break up large areas with an 8 pound sledge or small areas with a hammer and chisel. It doesn't go into detail on how much to break it up, but once you do, clean it up and wet the area down for at least several hours, preferably all night by leaving a hose trickling water onto it. Then prepare a sand-cement-epoxy mixture "according to manufacturer directions". Apply with a trowel, bringing the new layer level with the surrounding concrete and feathering it thinly at the edges. Another fix says to bust out the first 1" underneath the surface of damaged concrete with a chisel and hammer, then undercut the edges so it has something to grab onto (pic looks like a pyramid bottom on the side profile of the concrete). Then it recommends a cement paint to prime the surface followed by a mortar fill. Use the stupid questions thread next time.

>>2920786
thanks anon, this is the kind of distilled advice I hope for coming here
>says it's either scaling or spalling
it is neither, this is a week old undamaged slab. it’s simply a geometric defect in the surface due to a poor troweling job, purely cosmetic. I believe the potential fixes you detailed still apply
>bust out the first 1" underneath the surface of damaged concrete with a chisel and hammer, then undercut the edges so it has something to grab onto
So, in an ordered list, just for my clarification:
>grind the edges of the affected area at an undercut angle (temporary “control joints”) 1” deep
>break up the rest of the area 1” deep using a chisel and hammer
>clean, prime, and hydrate the surface
>fill the recess in with mortar, feather in edges
>broom finish to match the existing
My question is why use mortar over another type of fill? Would using a sand/cement/epoxy mix be any better or worse?

>>2920806
Flip the pyramid so the bottom is wider than the top. I used my wife's phone to take a couple pictures for you so you can see yourself. Order of operations is:
>chisel
>clean debris
>wet it down
>apply cement paint primer (with brush)
>apply mortar fill before primer dries
>give it some time to stand, then finish troweling it
>broom it
There is a concrete bonding adhesive that you can buy nowadays. Sika sells it for not much and you replace a portion of the water with it. I think you can apply it to the surface you're repairing to help with adhesion, too. That would be good to use. There was another anon talking about this type of thing in another thread. See >>2918482
So he recommends etching with an acid and scarifying the surface with a grinder. I dunno if you'll want to etch because it might ruin the rest of your concrete, but putting lots of tooth in the surface you chisel (or grind) out is a good idea.
>My question is why use mortar over another type of fill? Would using a sand/cement/epoxy mix be any better or worse?
I don't really know the answer to that. Probably gonna have to do some digging with a search engine to find an answer to that. A mortar might look pretty similar to the existing concrete if you use the same portland cement base, just nix the gravel. I think you can't really go wrong with a mortar fìll, but it's possible the epoxy mixture might have better adhesion. I don't know the full story, though. Good luck.

>>2920806
Nice drawing, tho.

>>2920819
Don’t get the pva bonding stuff. It’s just whiteglue. Literally.
I got this crazy blue vinyl based stuff for floor patches/leveller and it’s amazing shit and seems to be totally waterproof.

>>2920762 (OP)
You want some stuff called sand topping mix rough the surface a bit and trowel it over to the desired finish. It comes in a 60lb bag and will be near the regular concrete at your local big box.

>>2920762 (OP)
>ignore my lewd footprint
No I don't think I will

>>2920762 (OP)
Rushjob.jpg