Bricks, Masonry, Asphalt and Concrete - Blistered(?) blocks?

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skibum
03-09-02, 02:07 PM
I have a 1956 Bungalow. The walls in the basement are hollow blocks. I've noticed over the last couple of years small dime sized divots appearing on the surface of some of them, not all. I examined one of these before it pushed all the way thru the whitewash. It's about the size of an M&M and had a strong metalic smell. Is this just normal with a block that old, or is it a symptom of something else. I'm going to have to re-paint the walls. What can I patch these divots with? What can I paint the walls with?

Thanks!

BRICK4U
03-09-02, 03:01 PM
... made with real cinders! The "dime sized pops" smell like metal because they are "rust"! These "popouts" are something unique to block made with cinders or ash as an aggregate. Most concrete block produced today use other materials as aggregate or make sure that the ash has been processed to prevent the rust pops. (They didn't think like that back in the 50's.)

Most likely, your walls have gotten extra moisture in them at some point... causing the aggregate to rust... and expand just like water when it freezes.

Unfortunately, there is no paint that's going to stop the popouts. I'd look outside to check the drainage away from the foundation walls... and make sure that you don't have any leaking.