drawn a blank round here - pallet quantities or drive to south
> yorkshire?!!!?
>
> anyone know who may have in stock in ?
>
> better perhaps is there an alternative?
>
> I'm rebuilding a rotted (from inside) chimney stack - seems SRPC is
> the stuff to use to try to not have the same thing happen again.... > > Cheers > Jim K
How old would this be? If it is a relic from the days before smokeless fuels, you shouldn't have a problem nowadays. And if the chimney has been emitting sulphurous fumes these days, the environmental health department of the local council will want to know about it.
I expect the bricks are "saturated" with sulphatey wastes from decades of burning....so when they get wet next time it will leach out and....attack the new OPC mortar....
I would have thought that if the acid is in the bricks from long ago it may well have already attacked the cement and neutralised itself or done so by absorbing CO2 from the air (But I'm no mason or restoration buff so others might know better how long this stuff can hang around.) You could try getting some pH - the 'universal' type - papers and testing some washings from the brickwork, to see how seriously acid they are, and even add a pinch of lime at a time to see how much it takes to neutralise.
Gosh, the old chemistry seems to be becoming a UK.d-i-y feature these days!
NT says to try lime - presumably as a lime wash - which would convert any sulphuric remains to gypsum one would expect, but how far into a brick this would get, one can only guess. You might try some washing soda or sodium bicarbonate to wash down the bricks, which ought to penetrate further as it would be less likely to solidify and block the pores.
I think you probably don't really have much to worry about if your chimney is not going to go on using sulphur containing fuels. It takes quite a lot of a liquid to dissolve a solid, and there is a fair amount of lime around each brick if you think about it. You say next time the bricks get wet acid may leach out, but you also said the existing mortar rotted from the inside, so there may not actually be any acid on the outside (is there lichen on the masonry: if so, it is unlikely to be acid). If the mortar was so badly attacked that the bricks are easily extracted and cleaned up: why not go the whole hog and dunk them in a bath of dilute lime water for a few days. That would sort out any residual acid for sure.
or used up all the cement and lead to the crumbling exterior issues I have to address?
TBH I am 3 storeys up and just want to do it as best I can within reason and cross fingers *I* won't be up there again
well there *was* yes .....see below
outside of what? the pointing is hanging out & crumbling, till i take it down I have no idea what state the (lime) mortar is in but suffice to say "it's all moving"....
MMM good ideas but the 3 storey/time thoughts apply here too ...
what easily available mortar mix will resist any possible attack the best? using part lime? searching out SRPC? NB I can;t have it too strong as the bricks are porous weak handmades that risk spalling if mortar too strong...
It does sound like you ought to be using lime mortar - which according to others here when it was discussed, does not have to be the silly expensive aged variety. Soft old bricks and modern hard mortar won't get on together. Shame you are not getting any replies from the experienced brick layers out there.
from what I've been reading that's not a good idea- cement bungs up the pores of the mortar and stops the lime getting the CO2 it needs to "cure", and there's not enough OPC to set by itself.... seems its "just lime" or "just OPC" mortars that work best... (exits behind parapet...)
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