Any concrete/block experts?

[gregory r]

grind out mortar joint and repoint, normally i would put an expansion material (asphalt shingles,felt paper)between the cinder block and concrete slab but your past that point. stone veneer would work also.


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This right here. I have been doing masonry for 40 years. If you dont put something such as plastic, felt paper etc, on top of the 4" block, before pouring concrete on top, the concrete adheres to the block, and as it dries and cures, lifts the top row of block slightly.
You can grout, parge, cover with stone, and it will not crack again.

 

[jags]

This right here. I have been doing masonry for 40 years. If you dont put something such as plastic, felt paper etc, on top of the 4" block, before pouring concrete on top, the concrete adheres to the block, and as it dries and cures, lifts the top row of block slightly.
You can grout, parge, cover with stone, and it will not crack again.

+1 to this.

Depending on the detail between the slab, block, vertical reinforcing etc. Concrete shrinkage lifted the top course.

 

[kipper09]

This right here. I have been doing masonry for 40 years. If you dont put something such as plastic, felt paper etc, on top of the 4" block, before pouring concrete on top, the concrete adheres to the block, and as it dries and cures, lifts the top row of block slightly.
You can grout, parge, cover with stone, and it will not crack again.

So do you suggest a re strike of the joint? I’m ok with the work but I want that joint to look right. I just don’t want the slab on top to crack


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[gregory r]

So do you suggest a re strike of the joint? I’m ok with the work but I want that joint to look right. I just don’t want the slab on top to crack


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You can take a 4" grinder with a 4" x 1/4 inch diamond tuckpointing blade, available at Lowes, Home depot, etc, and grind the cracked mortar out to about 1" depth. Then with a grout bag, and type S mortar, fill it, then strike it.
IMO, you have no settling, and no worries about the slab cracking, provided it is tied where it meets the house correctly, but that is a whole nother can of worms!

 

[Agross]

Again. Did any of the slab, porch top settle? I hope they put rebar in it. If they didn’t, they should have,. There should be control joints in it, especially something that size( sawcuts or joints).

 

[kipper09]

Again. Did any of the slab, porch top settle? I hope they put rebar in it. If they didn’t, they should have,. There should be control joints in it, especially something that size( sawcuts or joints).

They put wire mesh in it and put 2 saw joints in it.


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[ddd-shooter]

Rebar through the block and bent over into the slab is a great way to lock the slab in…

 

[gregory r]

Rebar through the block and bent over into the slab is a great way to lock the slab in…

 

[Rokbar]

I'm no engineer, but I don't believe I would worry too much about it. I'd seal it with something to keep water from getting in and possibly freezing. But I would think if it cracked all the way through and all the way around, the weight from what is setting on it will stablize the block. A lot of block walls crack some where over time.

 

[ben h]

I am a structural engineer, and I wouldn't worry too much about it either except for the aesthetic reasons. If it does bother you, grind it out and replace it. You only need to grind out a couple inches of the grout, so the grout on the back side will temporarily hold the load and it will be fine.

As for slab cracking, the #1 thing to prevent that is slab thickness (late for this one, but for future reference). Slab reinforcement is a good idea and will minimize crack width and differential settlement, but doesn't really help with "random cracking". Control joints also help, but going off the top of my head they need to be something like 10x the slab thickness, so a 4" slab needs to have 40" joints and nobody does that (per ACI-318).

 

[AAABucko]

First post ever but long time lurker. Im in the concrete supply business.
Like jags stated above it appears to be slab shrinkage causing the top to slightly pull inward. Based off what the picture showed. I would go to Home Depot and buy grey shade tile grout that comes in tubes much like liquid nails. It sanded/coarse and you will be able to get in there easily. I’ve used it many times and it’s components are very similar to block grout. It’s in the tile section.

 

[AAABucko]

Here is the product.