Spalling, an Introduction

This is Janet's restaurant Bacchino, where we used to get the best pizza in Mexico. I was sad to hear it closed.

The old wall is interesting. I'm not sure how old it is. Let's zoom in to a section just to the right of the picture above.

This is a classic case of what is called spalling. The old grout is whitish. Newer repointing is greyer, done with grout too rich in portland cement. The harder cement expands and contracts more than the softer brick, so the brick gets fractures and drops away. This happens when cement is used to repair old masonry which originally had lime grout. The cement will even blow out adjacent stone. You can see it all over town.

So...what happens is that attempts to repair invariably accelerate damage in the long run. NOTHING, but nothing, can convince the local builders to cut use of portland cement in the repair of old buildings and revert to the 100% lime grouts and plasters used by their ancestors. Current cement use has been practiced for generations, so builders are unwilling to change. Only a prolonged program of awareness-raising could turn things around.