Custom-formulated Concrete & Mortar - Or Overkill?

bob_cntrctr

Gentlemen,

This is a case of knowing enough to know to ask if what I think I know is really applicable or just over-thinking.

Century old 8" concrete hollow block wall. I've got one 3" hole that someone punched all the way through for a vent pipe, and a couple of 2"x6" holes punched through the inside walls into the cavity - looks like 2x6's were once lodged in there, though they're 3-feet above the floor.

They all need plugging.

But I recall a very interesting conversation once with a mason that specialized in heritage buildings, and him going on about the long-lost art of mortar formulation. About how old mortars were "softer", had some give, compared to newer commerical out-of-the-bag mortars. Sometimes, re-pointing a heritage building with modern commercial mortar will just accelerate degradation as the difference in rigidity and thermal expansion rips it apart.

So if I were re-pointing a whole wall of this place, I'd seek out such a guy and have him do it right. But here I'm just going to be plugging some holes. Not re-pointing a whole wall.

Waddya think? Is this applicable here and I really should find a mortar and concrete formulator? Or am I thinking too hard again and some sacrete will do?

Thanks.

Tscarborough

Just plug the holes with whatever you have. CMU were not practical until there was portland cement, so they are almost certainly laid in cementious mortar.

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6stringmason

I'd just shove some insulation in em lol.

Just kiddin btw

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stacker

i have done that alot.insulation,newspaper,cement sacks,whatever is handy.i leave it back 1/2 to 1 inch and fill with mortar.

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CJKarl

Yeah, If it's a CMU it's not THAT historical. IMO

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bob_cntrctr

We have a funny perspective here in North America where it's a big deal when a structure is more than a century old.

Actually, I when I opened the walls, I found the two 2x6 holes stuffed with newspaper from the last renovation - dated 1961. And bone dry!

So, thanks for the info. Inorganic stuffing and a patch it is.