Hydraulic lime sand

[dze]

I am looking for some advice on a sand to use with hydraulic lime, ok with the sizing and trying to use a local sand, the problem is with the aluminium oxide content of the sand which is 2.59, is this to high and what difference to the finished mortar does it make. Thanks in advance.

 

[biffvernon]

Why are you using hydraulic rather than hydrated lime? Is this some particular situation that requires it?

What do you mean by sizing being ok?

Not many people know anything about the aluminium oxide content of the sand they are using. Is that figure a percentage and how do you know? 2.59% is approximately buggerall - just a few grains of mica or feldspar mixed amongst the quartz would give you that and would make no difference to a lime mortar. You could add a lot of clay, which is largely aluminium oxide, to a lime mortar with no ill effects in most situations.

(Nice to see another Lincolnshire poster here. Welcome!)
(Ooo, and a joiner as well, doubly welcome )

 

[FCB]

Depends slightly on what you're doing with the lime: is it for rendering, plastering or something else?

Truth is, there's a lot of guff talked about sand grain sizes. Best thing overall is a sharp sand (graded) irrespective of whether your NHL is 2 or 3.5.

I've recently been using bagged stuff from a local builder's merchant (for convenience) which comes washed and free of of other possible impurities. That's what matters most in my humble opinion.

 

[biffvernon]

Now't wrong wi' a bit o' impurity. You have to eat a peck o' dirt in your life, as my granny said. (Well, it might have been someone else's apocryphal granny.)

 

[dze]

Thanks for the advice guys, I'm using NHL2 for pointing bottom 10 or more courses of my father's house wall, the wall borders the road so i thought NHL would set a little faster before the spray off the road washed it all out (this seems to be the reason the mortar is in a poor state as the rest is fine. The 2.59 is a percentage and it came from a data sheet. I'm just a humble joiner so go easy on me guys. Thanks once again.

 

[Flyfisher]

2.59% is approximately buggerall

two decimal places is more like precisely buggerall :wink:

 

[biffvernon]

Right. Just use 'sharp sand' with your NHL2 and you'll be fine. Sand:lime about 3:1.

Aluminium content is important when casting concrete beams for large bridges