Bricks didn't bond - too dry?

[VDubDan]

Hi all, did my first bit of work with facing bricks yesterday and have some bad results. I noticed when laying that they didn't feel right on the mortar, there seemed to be very little adhesion much after laying but I'd only used engineering bricks with holes before so put it down to that and thought I'd see how it went.

Anyway, it's 24 hours on, the mortar has set but I've got a bunch of bricks which aren't even remotely bonded to it. I literally just picked up the top brick off my one corner like it was just placed there - zero resistance all.

Only thing I can think is that they're very dry and sandy bricks and have caused the mortar to go off too quickly. The bricks are Ibstock Ivanhoe Cottage Blend and were fresh out of the wrapped pack. They have a water absorption rating of 19 whatever that means!

Am I on the right lines here? Or should I be looking elsewhere?

 

[^woody^]

A job for Mulder and Scully.

 

[VDubDan]

Anything to get Gillian Anderson round

 

[Ian H]

I’ve been relating some bricks that have been an Internal wall for the last 85years.

I have to submerge them in water for a few minutes to stop them sucking the moisture from the mortar.

 

[noseall]

REMEMBER:

Mortar/concrete/cement loves water.

Denying it water, whether that be by sun, heat, frost, or lack of, will kill it. Wet bricks will bond to muck much better than their dry mates.

 

[VDubDan]

I’ve been relating some bricks that have been an Internal wall for the last 85years.

I have to submerge them in water for a few minutes to stop them sucking the moisture from the mortar.

REMEMBER:

Mortar/concrete/cement loves water.

Denying it water, whether that be by sun, heat, frost, or lack of, will kill it. Wet bricks will bond to muck much better than their dry mates.

Cheers guys. So what's the answer here, give them a ten minute dunk before hand? I presume I just want to take the edge off and let them dry a bit before laying?

And will it cause any issues with efflorescence? Not too fussed about rebuilding this lot after wetting as its 90 percent underground but don't want to cause any issues once I get out!

 

[stuart45]

What mix did you use, and any plaz?

 

[VDubDan]

What mix did you use, and any plaz?

4:1 and a little bit of plasticiser yeah. I put literally a few mm in a bucket of water

 

[stuart45]

Sounds OK. Modern bricks only usually go as low as 20%. Engineering bricks are more like 4-7%. You need a certain amount of suction to help bond the mortar to the bricks.
Nowadays bricks are normally laid as they come on site, whereas in the old days when bricks were really soft and porous they could have been soaked. The idea was that the centre of the brick was damp and the surface dry. This allowed for a small amount of suction, without the brick soaking up too much of the water.

 

[23vc]

How wet was your mix? You can get away with a drier mix with engineering bricks but these will be much more absorbent so it won’t work. Wetter mix and/or soaking the bricks then letting them dry a bit will sort it I reckon

 

[stuart45]

He might be expecting the mortar to be like a glue. You often find on site that the top bricks could be pulled off the next day, but it's best to leave them alone and crack on before you get sent down the road.

 

[VDubDan]

He might be expecting the mortar to be like a glue. You often find on site that the top bricks could be pulled off the next day, but it's best to leave them alone and crack on before you get sent down the road.

Nah, I get you and now I've taken them down some of them would probably have been fine if I didn't need to get the mortar off. But some were outright loose before I'd got there.

I'll have another bash tomorrow!

 

[^woody^]

Very unusual for this to happen with any bricks at this time of year, even if they are sponge.

Soaking bricks risks efflorescence. You'll need to just quickly tap the brick on the surface of some water, if suction is the actual issue.

But I'd check your mortar mixture first, or the way you are laying the bed and the brick.

 

[VDubDan]

Very unusual for this to happen with any bricks at this time of year, even if they are sponge.

Soaking bricks risks efflorescence. You'll need to just quickly tap the brick on the surface of some water, if suction is the actual issue.

But I'd check your mortar mixture first, or the way you are laying the bed and the brick.

Cheers, yeah, I still don't quite get it. Not gonna try today as it's due to freeze overnight - but I'll get some fresh cement and go again at some point.

I did drop a brick into a bucket of water and it did fizz for a long long time, and was touch dry within a few moments of taking out so they're definitely very very high suction.

Would a too strong mix cause it? I was doing small batched and I guess it could have been closer to 3:1

 

[stuart45]

Stronger you make the more it sticks.