Building sand or Sharp sand for Rsj packing.

[Bouba]

Thank you for all your help to all who contributed

 

[Skimmers]

slate or steel shims

 

[Bouba]

Thanks Skimmers.

What about mortar please. Sharp sand or building sand. Which gives a stronger mix.

 

[i_am_fubar]

Larger aggregate gives a higher compressive strength but at the expense of a thicker minimum thickness.

 

[^woody^]

Larger aggregate gives a higher compressive strength but at the expense of a thicker minimum thickness.

WTF?

Op, either sand will be just as strong at the same mix ratio. However, building sand is more workable, easier to use, won't slump, and so is the one to use.

3:1 and no plasticiser

 

[RonnyRaygun]

Larger aggregate gives a higher compressive strength but at the expense of a thicker minimum thickness.

WTF?

Op, either sand will be just as strong at the same mix ratio. However, building sand is more workable, easier to use, won't slump, and so is the one to use.

No it won't. A larger aggregate requires less cement to get the same compressive strength, as there is less surface area to the same volume of material.
So for the same mix, sharp sand will give a higher compressive strength.

Neither should slump as they should be mixed semi dry so that it is less likely to contract and crack.

Anyway, doesn't really matter as either will be fine at 3:1.

 

[^woody^]

No it won't. A larger aggregate requires less cement to get the same compressive strength, as there is less surface area to the same volume of material.
So for the same mix, sharp sand will give a higher compressive strength.

Neither should slump as they should be mixed semi dry so that it is less likely to contract and crack.

Anyway, doesn't really matter as either will be fine at 3:1.

Rubbish.
Larger grains of sand?

And this extra strength is measurable in a joint of 10mm?

Sharp sand will slump more as it is rammed in, and the water vibrated

Theory is great in textbooks from an office chair I am sure

 

[RonnyRaygun]

Larger grains of sand?

Yes, as we both know, sharp sand has larger grains than building sand. Even the fact that the sand is sharper will make for a stronger mix than rounder grains, all else being equal.

And this extra strength is measurable in a joint of 10mm?

It would be measured using a standard test, so the thickness of the joint is immaterial.

Sharp sand will slump more as it is rammed in, and the water vibrated

In a semi-dry mix?

Theory is great in textbooks from an office chair I am sure

I've done my fair share of building work in my life, DIY and on site. I've installed more than a few beams into walls too.