clay brick repair


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Old 06-20-23, 06:23 AM
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clay brick repair

I have a patio area that is a concrete slab with old reclaimed Chicago clay bricks. The bricks are set on thick set mortar with mortar joints.

There is an area with 8 bricks along the edge that I removed because two of the bricks popped loose. In trying to clean up the grout joints surrounding the two bricks, six other bricks came loose from the chiseling.

It appears the original thick set mortar at the bottom of the bricks are very solid and won't come out easy. If I start to chisel out the mortar to get more depth to set the bricks with a new layer of mortar I may end up popping off even more adjacent bricks. I have heard that there are adhesives that I can use to reattach the bricks and may be stronger than setting it on a new bed of mortar if the original mortar is solidly bonded to the concrete slab. Is this true? If so, any recommendation of what kind of adhesive?
 
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Old 06-20-23, 07:07 AM
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It sounds like too hard a mortar was used. I think you are going to have a continuing problem with bricks loose or lightly held in place. I would carefully chisel out the mortar and re-mortar the bricks back in place.

If your bricks are the soft clay type I'd say a patio isn't a good application. If it were a wall or something off the ground I'd suggest a lime mortar but it's not the best at ground level where it can remain wet. Because of the wet/damp ground contact type S mortar would be good, but it's too hard to use with soft bricks. Type N would be better for the bricks but isn't great when used on the ground where it can remain damp.
 
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Old 06-20-23, 09:52 PM
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The problem is chiseling out the mortar under the original bricks is the problem. Originally there were two bricks that came loose. It is my attempt to chisel out the mortar that has caused more to come loose as there really isn't a good way to carefully chisel. I think the more I try to chisel the more bricks will become loose, I am working on number 9 now. That's why I am thinking an adhesive may be a better option and I have read somewhere adhesive may bond better.

These brick patio/deck and driveway, have been installed since 1992, over 800SF of it and they have been fine. The two bricks that came loose are on a step where one side is not restrained.





The only reason they came loose is I was walking on them, normally these bricks are not walked on because these steps lead down to a garden pond and half the time those bricks are submerged and full of moss, but recently I cleared out the entire pond to repair the plumbing to the water feature and to rebuild the wood bridge so I started to walk down those steps.
 
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Old 06-21-23, 05:41 AM
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You just need to be careful with your chiseling, especially around the edges that adjoin bricks that are still stuck. You should try holding the chisel more vertical so you aren't sending the energy sideways into adjoining mortar or brick. Use lighter taps as you near the border with good bricks. Or, you can grind out the old mortar. I don't know of an adhesive I would trust for your application. A step nosing (high stress, critical for safety), on the ground (wet) and under water (super wet) is a difficult situation. I'd stick with mortar.
 
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Old 06-22-23, 05:19 AM
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There really is no long term adhesive to substitute for mortar!

A pneumatic chisel would be best tool, it's fast and the pneumatic action is not as destructive as a hammer blow so less collateral damage!
 
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Old 06-22-23, 10:05 PM
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I was using a regular cold chisel and hammer when all I needed to remove was the base mortar for two bricks. When doing so resulted in loosening 3 more, I switched to a Bosch bulldog xtreme rotary hammer with a 1" chisel blade, not only that, I pre-scored the edges with a 4.5" angle grinder with a diamond blade, so as to not having to chisel so close to the adjacent bricks, but there is a limit how close I can get due to the grinder's shield and center wheel so my grinding was not 100% vertical more like 80 degrees tilted. Still more bricks came off. Like I said now I have ten bricks to deal with, and what I am saying is it seems even being extremely careful the adjacent bricks are coming off and more mortar that needs to be removed.
 
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Old 06-25-23, 08:21 PM
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I did more very careful chiseling this weekend and I am now up to 15 loose bricks, and now I need to chisel out even more and I can't believe I started off with two loose bricks.

I am now contemplating just removing all 28 bricks in the entire row that allows me to go gang buster chiseling.
 
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Old 06-26-23, 05:31 AM
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If that many are coming loose it's telling you they weren't solid to begin with. Removing all on the step and working fast might be quicker than chiseling carefully.
 
 

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