Mortar not hardening in damp weather

[s219]

I'm wondering if anyone has run into this -- I mortared down some concrete blocks to footings Friday (4 days ago as I write this). Due to rain and damp conditions for the last 2+ days, the mortar has never dried out and hardened. It did seem to set off and firm up in the first 24 hours, and the blocks feel securely stuck down to the footer (I tripped over one). But I can break off a chunk of mortar with my fingernails and it's clearly not hardened. It's still dark gray in color.

Assuming it can eventually dry out (we have 3 dry days coming), will the mortar eventually harden and be OK? I know there is an actual chemical reaction when the mortar first "sets off" but it seems that extended dampness is not allowing a proper hardening and curing.

I was thinking I would put some halogen work lights and a propane heater on the area tomorrow (not directly on the blocks) just to aid with some dehumidification. Right now everything is super damp and wet outside and this is on the shady side of my barn.

I had put stubs of rebar poking out of the footings and plan to fill the blocks with concrete mix to help them stay put, so the mortar may not be critical in the end, but I'd hate to move on with the project if the mortar can't be trusted. I had put about a 1/2" bed of mortar under the blocks and they will support quite a bit of weight eventually.



I used type S mortar for this. I had a little extra when done, and dumped it off to the side in a dry area. It did harden up and turn light gray, so I feel like that's a good indication it was a good batch and that the problem with the footings is due to dampness and moisture on the ground.

 

[Streetcar]

Replace mortar, it sets through chemical reaction not by drying. You have bad mortar

 

[RNeumann]

It sounds like it isn’t good. Concrete will harden underwater.

Take a chunk and bring it inside and see what happens. The color doesn’t matter much- that can change some with humidity.

If they are stuck together enough and you are going to grout it anyway it may be borderline ok. But clearly something is wrong.....and I don’t think it’s the weather.

 

[s219]

Replace mortar, it sets through chemical reaction not by drying. You have bad mortar

At the end of my work, I scraped the extra mortar out of my mixing tub and dumped it off to the side in a dry location. It hardened and changed color by the next morning. So that suggests to me that the mortar mix by itself was OK.

 

[s219]

Take a chunk and bring it inside and see what happens.

Good idea -- I chipped off a couple blobs from inside the blocks and brought them indoors. If those don't look good by tomorrow I think I will knock the blocks loose and start over.

 

[Billrog]

The motor is likely fine no need to double guess yourself.

 

[Streetcar]

At the end of my work, I scraped the extra mortar out of my mixing tub and dumped it off to the side in a dry location. It hardened and changed color by the next morning. So that suggests to me that the mortar mix by itself was OK.

You have something different with the block mortar verses the dumped mortar. Block mortar has failed and needs replaced. Mortar will set as long as it has enough moisture. Excess surface moisture will not harm mortar

 

[Tractor Seabee]

What was the temperature outside. Cold weather will delay or even stop the hydration process w/o additives and blanketing.

Ron

 

[Snobdds]

After 4 days, a finger nail should not be able to flake anything off. It should take a cold chisel.

However my gut says its ok, especially if grouted in.

 

[Streetcar]

What was the temperature outside. Cold weather will delay or even stop the hydration process w/o additives and blanketing.

Ron

WEather has been warme4 than normal recently