Crumbly Mortar

[Ninja_1980]

Hi

I've just finished blocking up an old door opening. It's been a couple of days and the mortar doesn't seem to have set properly. Some areas are really dusty. If you rub your finger on it, dusty sand comes away.

I've used a 4:1 mix by hand. In retrospect, I'm not 100% confident I've mixed it well enough. A mistake I won't make again.

Anyway, the wall is going to be rendered. So the question is whether to grind out and repoint or just render on top.

Thanks

 

[^woody^]

Brush some diluted PVA on it and it will be OK to render.

Drying too fast or not tooling the face generally causes this.

If you did not mix it well enough, you would see the mix being different colours.

 

[Ninja_1980]

Many thanks.

I did wet the blocks but it's been quite hot recently. I'll pva the blocks and crack on.

Thanks