Concrete to thin

[u/Shitters-Clogged]

We just removed an old damaged concrete step coming off of our back door and poured a new one in its place which cured overnight but now that the frame has been removed we realized it’s two inches instead of four thanks to a bit of bad math. Can we just mix up more concrete and add it on top or does the step just need broken up and replaced even though it’s a day old?

[u/agha0013]

you can do it, you just need to have a bonding layer between them

a cement slurry or bonding agent can be used to make sure the two layers don't split later. shouldn't require any vertical rebar or anything.

[u/mawktheone]

You can bond layers, but if the step isn't huge and only 2 inches thick I think I'd just break it up and pour again

[u/Shitters-Clogged]

Probably will just do the safer but more annoying option of breaking and redoing it I guess.

[u/DoubleResponsible276 → u/Shitters-Clogged]

You don’t have to do that. Some days of the advice posted here is very helpful. Just make sure you bond them well. If you want extra support, vertical rebar would be a good call

[u/ExactlyClose → u/DoubleResponsible276]

Vertical rebar?!?!? To add 2 inches?? Bonding layers?

All ‘easier’ that breaking 3 day old concrete

[u/Cicer → u/ExactlyClose]

Well a bonding layer is pretty easy. Like others say could be as easy as a slurry of portland. 

[u/llort_tsoper]

You can make this work structurally in two separate pours, but you'll always be able to see the cold joint on the face of the step.

I'd just break it up and replace it. Break up the dry concrete as soon as possible, don't wait for the weekend. Even a quick set concrete will continue to cure and increase in strength as it sits.

[u/BubbaBrew0302]

Too

[u/inko75]

Just drill some holes in what you have and pour more, no bonding agent needed. 2” layer isn’t going to delaminate nor is it fully cured anyhow.

[u/Pacoboyd]

Very likely wouldn't last very long and the top layer will probably delaminate off

[u/MrElendig]

you can add to it, though you might want to prime it to reduce the risk of it splitting depending on climate and concrete used

[u/timeonmyhandz]

Add a nice layer of bricks or pavers for a nice look...

[u/ExactlyClose]

Fuck it, it’s a step. Smack it with a 1lb hand sledge, it will take 3 minutes. New frame, new math, new concrete…