Update on that old lime mortar mix I swore by

I was reading a trade journal from the UK and found out that adding too much Portland cement to a lime mortar for historic repair can actually trap moisture and cause spalling. I always thought a little extra cement made it stronger and was fine. Saw a photo of a 1920s chimney in Edinburgh that had failed after a repair with the wrong mix. Has anyone else had to adjust their approach for older brickwork?

3 comments

3 Comments

xenarobinson1mo ago

Doubt it causes that much damage if the mix was only a little off.

the_ruby1mo agoMost Upvoted

A little off can still mess things up. If the ratio is wrong by even a few percent, it can make the whole batch useless. Seen it happen with concrete where it just never set right.

jesse_cooper1mo ago

Yeah, that "little off" thing @xenarobinson mentioned is exactly what the article warned about, it can lock in water and wreck the brick over time.