Discussion in 'Builders' Talk' started by Aron82, Aug 29, 2021.
Hi is hydraulic lime suitable for relaying spalling bricks or just for repointing thanx.
I have used hydraulic lime for brick laying and for laying rubble stone when I built my house 12 years ago. To date their have been no issues with stability, just keep the lime mix strong, about 4:1, 5:1 maximum, mix it the day before you need it in an ordinary concrete mixer. leave it in the mixer and re mix just before use.
The trick is not to re lay spalling bricks
For.mixing hydraulic lime a roller pan mixer is best, but a drum can be used.
I use around a 3/1 mix for NHL 3.5 depending on the sand. Mix dry for 5 mins, then add water carefully and mix for 15/20 mins, let it stand and fatten up for 20, then remix for a couple.
I'm not i'm using handmade bricks from a demolished garage wall.
I managed to rebuild a window reveal not perfect but a few millimetres out my problem again old bricks have a lot of suction even after soaking them in bucket for 20mins once I laid the brick I couldn't level it proper using spirit level as it wouldn't move didn't want to break the bond any tips for this sorry to waffle on
I've been told by a master lime plasterer that a 2.5 to 1 part lime for spalling brickwork is ok what u think.
Also how long does hydraulic lime take to set fully
I can't comment on plastering with lime as I have not tried it, only laying. The bricks I used were old hand made, some going back to 1600, I did not wet them prior to laying as I had no suction issues, just lay the mortar bed and get the bricks on quickly. I would not re lay spalling bricks but I think you are intending tp plaster over them, the lime plaster will blow out just as the bricks have due to the moisture in the wall. The lime to sand ratio will be different for plastering as it is for laying, I would go with 2.5:1 for plastering.
are these ratios suitable for bricklaying.
That's what I use it for. Pointing, bricklaying and stonework.
I use 2.5:1 for pointing, and I believe it is good for bricklaying, some say 3:1. I found the NHL 3.5 went off quickly enough, within an hour or so it was firm to the touch. I just misted (not a spray like say, a shower) every so often it and protected it from sunlight and wind for a couple of days. NHL Lime, I understand takes some days, depending on the weather, to fully go off, hydrated lime much longer as they have different curing processes - NHL uses water as the catalyst and Hydrated uses the CO2 in the air.
You may find this site useful - I did.
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