Kiln dried + cement, or dried building sand?

[robinbanks]

My Tobermore pavers are laid on 6mm bedding aggregate rather than sand. So far so good, easy to work with etc but I suspect that rain is successfully washing the kiln dried joint sand down into the aggregate sometimes as I keep finding random joints that were formerly filled have reverted to being a gap. I also suspect that this is only likely to happen when the sand is new, as over the years soil and other garden detritus will wash though the sand and bind it, but I don't want to keep pouring bag after bag into it to have it keep washing into the aggregate

I'm pondering on a strategy to counter this, either mixing cement into the KDS at a weak ratio, like 15 even 20 to 1.. or switching to using building sand and just leaving a large amount spread out indoors to dry it out, reasoning that it'll be less likely to get washed about in the rain than KDS does.

If cementing it I don't want it so strong that it makes damaged pavers hard to remove, nor locked in place so absolutely that it doesn't resettle and block up again if movement of a paver starts to occur..

Any thoughts or alternative proposals?

 

[^woody^]

Polymer sand, or lime, not cement.

 

[noseall]

My Tobermore pavers are laid on 6mm bedding aggregate rather than sand. So far so good, easy to work with etc but I suspect that rain is successfully washing the kiln dried joint sand down into the aggregate sometimes as I keep finding random joints that were formerly filled have reverted to being a gap. I also suspect that this is only likely to happen when the sand is new, as over the years soil and other garden detritus will wash though the sand and bind it, but I don't want to keep pouring bag after bag into it to have it keep washing into the aggregate

I'm pondering on a strategy to counter this, either mixing cement into the KDS at a weak ratio, like 15 even 20 to 1.. or switching to using building sand and just leaving a large amount spread out indoors to dry it out, reasonjj in by that it'll be less likely to get washed about in the rain than KDS does.

If cementing it I don't want it so strong that it makes damaged pavers hard to remove, nor locked in place so absolutely that it doesn't resettle and block up again if movement of a paver starts to occur..

Any thoughts or alternative proposals?

DON'T ADD CEMENT! It will cause bloom on the surface of the paviors. You use to be able to buy joint stabilizing solution, which locked the sand in place.

 

[Ivor Windybottom]

I once made a bit of mortar with KDS for a bit of patching up, as it was all I had at the time.

It just crumbled away. I guess it's composed of rounded sand particles, not the jagged bits that cement needs to grip into.

 

[noseall]

I once made a bit of mortar with KDS for a bit of patching up, as it was all I had at the time.

It just crumbled away. I guess it's composed of rounded sand particles, not the jagged bits that cement needs to grip into.

More likely dried out too quickly. Mortar loves water. Keep it wet and it'll dry like Bell iron. Dry it out quickly and it'll be as good as dust.

 

[Ivor Windybottom]

Not sure. Seemed to be mixed up ok and went on fine. But when I touched it the next day it just fell apart, it was basically tiny grey balls that weren't stuck together. I know new mortar is weak, but this was totally different.

It may be particle shape, or perhaps it doesn't have any of the fine silty powder that building or sharp sand have. I'm wondering if they seive this stuff out to make it cleaner/easier to sweep off block paving. Don't think it was too dry, it was definitely workable. But perhaps the surrounding brickwork sucked it dry.

Have others tried it?

 

[robinbanks]

It's very fine, perhaps less space for moisture between the particles of sand and cement with it, and if it was laid on dry blocks that sucked the heck out of it it could have ended up too dry for the cement to crystallise properly? Summer too?

I can mix some up here to see how it behaves, will let you know