Spalling Bricks caused by Portland Cement

[laptoplarryspc]

Yeah you cant beat lime mortar putty

[gillyboy1971]

I agree with Alex here, and same question. I dont understand why OPC would have caused this alone. Could you explain more on here?

[alex2000uk]

Very intresting, should one avoid using portland cement. or was sand blasting the main culpirt. Tell us more in the intro please. Were these old bricks or new bricks , they certainly look new.

[StevenEElkins]

It's a combination of the two. Sandblasting removes the protective fire skin from the brick which allows the brick to absorb more moisture. Then when you add the portland cement you create a barrier for the moisture to escape. What you end up with is the brick deteriorating much more rapidly because the moisture is now forced through the brick. The moisture that would normally travel through the softer, porous mortar can not because the portland cement creates a sort of dam effect.

[StevenEElkins]

Your mortar should be the sacrificial component in a masonry wall. Plus whoever re-pointed this wall did a horrible job because they allowed the new mortar to push up on to the face of the brick giving the impression that the mortar joint is much larger than it really is. Another example of another historic structure that has been destroyed by incompetent idiots. Another thing these fools do is cover these buildings with a sealer to seal the bricks. This just traps even more moisture.

[brickmason26]

@StevenEElkins

chimney sealer is a breathable sealer, only thing I use after many sealer failures, 10 year warrenty, not a sales rep just sharing trial and error.