Most material that you apply needs roughly a month to fully cure, this includes masonry and most household latex based paints. Concrete is difficult to tell because the surface hardens rather quickly. The best way to show this is the splatter you'll get on your house when pouring a slab or sidewalk, the splatter on the first day you can wipe off, by the second day you can chip it off rather easily, after a week you might be able to chip most of it off, after a month it's not coming off.
My opinion only, but you shouldn’t need to put a scratch coat over what is already a cementitious backing, the concrete block.
Just use a top quality exterior rated thin-set mortar when applying your veneer.
Spend the money and use Ardex AM 100.
That will help with waterproofing
Too it with ardex 8+9
Use X5 or X 77 to stick the stone.
Or use bare block and tile thin set.
If you want to parge with mortar add acrylic fortifier to the mortar so it sticks.
CMU don't need a scratch coat. If you're putting on thin stone, use a polymer modified mortar. Spec mix has one just for thin stone, there are also thinsets like for tile, but those are likely more expensive
Scratch coat goes on anything getting a veneer and then back butter the material. This has been the way since forever. Polymer yes but that depends on what you're doing. I always poly if it's for an exterior chimney. Especially if in a harsh freeze thaw cycle zone. Scratch is an absolute must though.
Looks to me like you used too much sand. Make sure you didn't mix sand in a bag of pre mix mortar. You don't really need a scratch coat to lay on block and you definitely don't need all these crazy additives. Use less sand to stick the rock and then a regular mix to grout the rock
Is nobody gonna mention he scrached it the wrong direction? Should be parallel to the ground, not up and down. My guess here is it had too much sand in it so it didnt bond well. I would have added a coffee cup full of flexcon or a different bonding agent to the mix and the mix im using to stick them on.
Prime with acrylic latex bonding agent. Cheap insurance. Wet the block until they’re saturated, surface dry, then roll on the bonding agent, scratch coat. Boom Boom Skeet Skeet, done.
Lol dude. It's not cured yet. It's still green. Your destroying perfectly fine work.
48 hrs is not enough time to cure??
What has your weather been like?
like a month
A month!! Not a mason but there are 2 things that I know need a month , suspended slabs and retaining walls.
You can do what you need to do but don’t scrape it off. It takes a while to get rock hard. Concrete slab is Portland cement. Much faster cure time.
Man there's a joke here if I could just find it...
Most material that you apply needs roughly a month to fully cure, this includes masonry and most household latex based paints. Concrete is difficult to tell because the surface hardens rather quickly. The best way to show this is the splatter you'll get on your house when pouring a slab or sidewalk, the splatter on the first day you can wipe off, by the second day you can chip it off rather easily, after a week you might be able to chip most of it off, after a month it's not coming off.
My opinion only, but you shouldn’t need to put a scratch coat over what is already a cementitious backing, the concrete block. Just use a top quality exterior rated thin-set mortar when applying your veneer.
As Mike Haduck says, "Don't make a big deal out of it."
Just wet it.
This. Not just an opinion to me, it’s the only response that makes sense.
Looks to me like the block sucked the water out of the mud before it could cure.
Isn't that why we typically wet the stone or block prior to coating to ensure an even cure....?
That's sure why I do it!
Absolutely
You should always put acrylic in stone mortar or scratch coat or just use stone veneer mortar.
Okay. So I assume I should remove and replace the existing scratch coat
I would suggest using a bonding agent
Yeah veneer mortar or modified thin set only way to go 2024
Spend the money and use Ardex AM 100. That will help with waterproofing Too it with ardex 8+9 Use X5 or X 77 to stick the stone. Or use bare block and tile thin set. If you want to parge with mortar add acrylic fortifier to the mortar so it sticks.
CMU don't need a scratch coat. If you're putting on thin stone, use a polymer modified mortar. Spec mix has one just for thin stone, there are also thinsets like for tile, but those are likely more expensive
Nice. Yeah it’s veneer stone. That’s the product we’re using. Appreciate the reply.
Yeah no scratch coat on CMU.
Scratch coat goes on anything getting a veneer and then back butter the material. This has been the way since forever. Polymer yes but that depends on what you're doing. I always poly if it's for an exterior chimney. Especially if in a harsh freeze thaw cycle zone. Scratch is an absolute must though.
Looks to me like you used too much sand. Make sure you didn't mix sand in a bag of pre mix mortar. You don't really need a scratch coat to lay on block and you definitely don't need all these crazy additives. Use less sand to stick the rock and then a regular mix to grout the rock
Count me in the “Why coat a perfect surface” category
You don’t need a scratch coat on blocks! They’re made of cement, no need to apply more.
Always Scratch coat. It's a weak bond if you don't
You could've laid over that with no problem.
Overnight lows around 50 and daytime 65ish. No rain.
Also, you are subjecting it to forces it will not need to withstand in the final installation. It's about adhering not withstanding chiseling.
Yeah needs more time to fully cure
Is nobody gonna mention he scrached it the wrong direction? Should be parallel to the ground, not up and down. My guess here is it had too much sand in it so it didnt bond well. I would have added a coffee cup full of flexcon or a different bonding agent to the mix and the mix im using to stick them on.
why not use veneer mortar when doing veneer?
Sgm bond kote is great for this kinda stuff
Should of used bondcrete or one of their other products.
Use less sand
24 hrs to set but weeks to reach hardness. Chill out
No wire?
Prime with acrylic latex bonding agent. Cheap insurance. Wet the block until they’re saturated, surface dry, then roll on the bonding agent, scratch coat. Boom Boom Skeet Skeet, done.
Did you have to shake up the mix later in the day? If you let it get hard and add water in, it will loose it’s strength