Well they are called cinder blocks because back in the day, they used coal ash as part of the aggregate mix to make them. As you might expect they put it in everything concrete “lots of coal ash and a pain in the ass to get rid of” and the high acidity of the coal ash causes the cement to degrade. I know this because the mortar used to build my old house used said coal ash which caused said house to slowly decompose like it was bit by a komoto dragon, I then spent much of my time tuck pointing said house to keep it upright.

Well they are called cinder blocks because back in the day, they used coal ash as part of the aggregate mix to make them. As you might expect they put it in everything concrete “lots of coal ash and a pain in the ass to get rid of” and the high acidity of the coal ash causes the cement to degrade. I know this because the mortar used to build my old house used said coal ash which caused said house to slowly decompose. I then spent much of my time tuck pointing said house to keep it upright.