Wet weather and mortar

[LSB]

It was dry this week, shouldn't have believed it, but HID laid first layer of blocks and now they have got wet.

He has covered the top, but is worried about the mortar being affected by the damp.

 

Is this an issue or will it just take longer to set hard as it still seems quite soft today, or is it because it's covered and it needs air.

We have been told not to let the blocks get soaked hence covering them loosely with a tarp.

 

The usual 1 step forward 2 steps back 😞

 

FYI blocks are 3.6n H&H and these are the ones that will be below the DPM.

[Radian]

46 minutes ago, LSB said:

Is this an issue or will it just take longer to set hard as it still seems quite soft today,

Unless there was so much rain that it purged the cement from the sand, it'll be fine. The mortar sets through a slow chemical reaction that takes place in the presence of water. Drying out before this process is complete is the main danger. Also freezing which makes the water expand, so wrecking the matrix - but you have neither of these concerns. Covering with a tarp won't have any adverse effect. One thing it can help with is to retain the heat given off by the exothermic reaction as it sets.

 

Mortar can remain quite soft for a few days but actually achieves good compressive strength nonetheless. In fact, its load bearing abilities can appear within hours. It will depend greatly on the ratio of the mortar mix. What was yours? e.g. 5:1 sand/cement? 

[Dave Jones]

no issue at all. trenches often have a couple inches of water in them when conc is poured for example.

 

The problem is when face brickwork is not dry and it rains, struggle to ever get the staining out of the courses below.

[LSB]

1 hour ago, Dave Jones said:

no issue at all. trenches often have a couple inches of water in them when conc is poured for example.

 

The problem is when face brickwork is not dry and it rains, struggle to ever get the staining out of the courses below.

as we are cladding / render then at least we don't have to worry about this.

After all there are plenty of things that we do need to worry about.

[EdSt]

Hi, just jumping on this thread with my issue.. block layer was suppose to come yesterday but was a no show, arrived this morning unannounced and caught me unawares as I was off to work. He set his lads going on the 7M 215mm block flat wall they are building for my block and beam and himself left site. When I spoke to him mid morning to see how things were he still wasn’t at my house. Came home this evening to find standing 30mm of water in parts of the trench and a load of, what looks like run off mortar, in the trench (looks like a lot - might they have thrown some sand in to try and soak up the standing water - is that a trick if the trade?) Any way there were token tarps thrown here and there but only half covered and not tidy. Had a poke around with a wall tie about 6pm and found the bottom beds soft and exposed vertical ones soft and washed out not much better now at 1130pm. The trench had a load of fluffy bubbles on the sand/mortar spoil like which I guess is the plasticiser. I’m not happy, and don’t see why I should have to compromise on a weaker wall, he can’t be saying this is top notch work - for one he wasn’t around. However ,I read in a few of the forums that actually mortar isn’t too affected by wetness. Please can the experienced  brick/block layers provide their thoughts? I’m not to worried about the cosmetics as the wall will get rendered. Is the structural strength compromised and does it all need taking down and starting again? It’s a outside wall to carry the end of 4m block and beam patio. Thanks in advance. 

[EdSt]

..just to add, I messaged him with some pictures to say a lot of mortar had washed out and he said he’d come repoint when he comes back to finish it. 

[Dave Jones]

yeah thats a take down. Why didnt they just lay some damp across the top to protect it ? cowboys.

[EdSt]

Thanks Dave. I’m not sure. There were plenty around covering block stacks which were lower priority.