Concrete step - did I mess this up?

[severalservals]

Hi, all. I had a broken concrete step and I've tried to repair it, but I'm wondering if I botched the job. Half the step had crumbled away and needed to be rebuilt almost from the level of the step below it. I used a bag of concrete mix and built some wooden forms to keep the wet concrete in shape.

My mistake may have been that I didn't wait for the concrete to dry between courses, but applied it all until I had the rebuilt section level with the existing section. It's been more than a week and while the new step holds its shape and might be solid enough to step on, it's still damp enough that I can score the top with a fingernail and the edges are crumbly.

Will it continue to harden up over time, or should I just tear it down and start again, letting each layer of concrete dry before I apply the next? Thanks very much for the help.

 

[bud16415]

I would wait.



The trouble with bag mixes is some of them are light on Portland and the dry mixture is not evenly mixed to start with. I always take some time to mix the dry really good before adding water and then mix that really good. I have also sometimes added a little more Portland. It should fully harden but if it was pretty thick and the outside temps are cooler it would take a while.

Welcome to the forum.

 

[severalservals]

Thanks for the reply. That's great news. I'd of course much rather not have to tear the step down and start over. Thanks also for the tip about mixing the dry concrete before use.

Would it have been better if I'd let the concrete dry between courses?

 

[bud16415]

Not really it depends on how wet the mix was and if it can support the layers below without pushing up the lower step. It does not dry it is a reaction and it cures it will even cure under water.

The bags are paper with a plastic liner and once opened I don't know how many times i have tried to save a half a bag only to look at it 6 months later to find it has cured into a solid block. Some people when setting posts just mix the contents and pour it in the hole. Some throw in a cup of water some just let the moisture in the soil cure it.

Worst that can happen is it might crumble sooner than you would like and you can patch it again. Best is it hardens up and you are done.

For small repairs I like a product called cement-all you can google it and read and watch vids.

Good luck let us know how it comes out.

 

[JoeD]

Exactly what did you use for the step?
Concrete is not done in layers.. It is poured all in one piece. After a week you should not be able to score the concrete with your fingernail.
Post some pictures.

 

[severalservals]

I'm sorry. I thought I'd replied to you but looks like my browser crashed before I clicked "post."

I used a bag Quikrete mix, like the one in this link (though this might not be the exact one): https://www.lowes.com/pd/QUIKRETE-60-lb-High-Strength-Concrete-Mix/3006078

I think bud16415 is probably right, that my problem is in poor mixing. I didn't mix up that bag at all, just poured some in a bucket, mixed it with water, applied til I was done and repeated. I did take a stab at sheet curing it, with a folded up shower curtain on top of it held down by bricks along the margin. Weeks later, I can still crumble the edge with my hand. I posted a picture below. The front is rough because I actually scraped some of the concrete away to level it with the existing step. I figured I'd do a finishing coat of mortar after.

Now I figure my best bet is to tear it down, get another bag of concrete and do a good mixing job before I try again.

Exactly what did you use for the step?
Concrete is not done in layers.. It is poured all in one piece. After a week you should not be able to score the concrete with your fingernail.
Post some pictures.

 

[bud16415]

Sorry it didn't cure for you. You might want to look at this line of products for your small job once you get the old fix cleaned out. Watch the videos.

https://www.homedepot.com/p/Rapid-S...struction-Material-02010055/202188447#overlay