Sharp sand in mortar mix

[diyreg]

A question for the experienced builders on here...

I'm having an extension done and my builder is using sharp sand for the mortar mix and says this is equally as good as using building sand and that as it's all being rendered over, the colour whont be seen anyway. Is this true and is it acceptable? I've never heard of it being done before

 

[stuart45]

He's making hard work for himself not using building sand. Washed and sharp sands were fine when lime mortar as being used, but with cement mortars they are not so easy to use.
Is he an experienced bricklayer?

 

[diyreg]

He's making hard work for himself not using building sand. Washed and sharp sands were fine when lime mortar as being used, but with cement mortars they are not so easy to use.
Is he an experienced bricklayer?

Thanks for your reply.

Yes, there's two guys and they're both very experienced bricklayers (from Poland) and are doing a very tidy job. Mortar is designed to be weaker than the blockwork and hence any movement doesn't crack the blocks, so my main concern is if concrete is too strong and the blocks cracked with any future movement.

 

[^woody^]

There is an inherent inflexibility with sharp sand mixes, which could lead to cracking in months/years to come as the building moves naturally. This will be even with weaker mixes

I can't think of why he would use sharp sand by choice