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Mortar bonding after brick movement

Postby silvershadelynx » Mon Jul 17, 2023 8:17 am

Dear all,

I am a beginning bricklayer and I want to do some small masonry jobs on my house.

For example, I have successfully filled some holes in a wall with new bricks. Our house dates from 1926 and has stone walls.

Yesterday I built a window sill. The bricks were at an angle (pointing downwards) and before I placed mortar I test-laid all the bricks in dry condition to make sure everything fits and looks ok. That all went well.

Then I placed mortar and laid the first brick. This one slid off the wall. The stone also compressed the mortar too much. So I quickly placed a wooden lath on the wall and placed the bricks on this lath. After that it went well and, in my opinion, I built a neat window sill.

Unfortunately, I then made a mistake: after 3 hours, I began to worry about whether I could still remove the wooden batten and carefully pulled it forward. This took a lot of strength, because there were 13 bricks resting on it. When I pulled the lath forward a few millimeters, a number of stones began to slide with it, forward.

I had hoped that the lath would come off without sliding stones, but I was thus too quick to remove it. In retrospect, I should have done this after the mortar had hardened. I carefully pushed the bricks back and carefully pressed on the mortar with a tuck pointer.

The mortar was on the damp (wet) side and beforehand I wet the bricks as well as the wall. I also misted the mortar with water every hour. I'm wondering if this had any positive effect in this situation?

On the face of it, everything seems fine and neat. But I now doubt whether the adhesion is good enough because, as I learned after this mistake from a neighbour, you have to work within 30 minutes and not move stones after that. Do you guys have any idea if this can still be good and how I can test it? My plan is to let the mortar harden and then press on it to test if it seems to adhere well.
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Simply Build It

Postby stoneyboy » Tue Jul 18, 2023 9:02 pm

Hi silvershadelynx,
Sounds like you have done all the right things especially damping all parts. You could try lifting one of the bricks to see how good the adhesion is - if it lifts easily you’re back to square one.
Regards S
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Postby silvershadelynx » Wed Jul 19, 2023 7:31 am

Hi stoneboy, thanks a lot for your response!

I will check it after 2 weeks - (I'm on holiday first) - and then pull it up with some force. If it doesn't come loose I'll accept it - it just looks very neat - which makes it a bit frustrating for me as a first time brikclayer and perfectionist.

I'll try to put a picture online of the window sill after I'm back from holiday.
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