Sandstone Patio with lime - what mixes?

[MdB]

I don't think I would use hydrate / putty as if it stays damp, it won't set ever.

I have done a couple of jobs where I used some hydrate based mortar to point walls down to bare earth. Where the mortar touches the earth, it hasn't set a year later. NHL sounds a better idea to me (NHL 2??).

 

[Flyfisher]

That settles it then. No hydrate in this case. I've got some white cement though.

 

[Schoolmarm]

8)

 

[AMc]

I don't think I would use hydrate / putty as if it stays damp, it won't set ever.

I have done a couple of jobs where I used some hydrate based mortar to point walls down to bare earth. Where the mortar touches the earth, it hasn't set a year later. NHL sounds a better idea to me (NHL 2??).

Hhmmmm that's not good news. Now to find a better understanding of the various grades of NHL.

 

[AMc]

Well I contacted Mike Wye in the end and got the following useful information...

When laying the slabs there are 2 options, you could use a 2/1 (sharp washed pit sand / 1 Castle NHL 3.5) mix or you could use a 3/1 mix (sharp washed pit sand / 1 Castle NHL 5).

So I asked

Is there any reason not to go for the NHL5 mix given sand is cheaper than lime?

and got this reply

Normally the NHL5 option would be fine, potentially you should do a 2/1 mix in any high traffic areas just to make sure the patio will last. The delivery to Norfolk for 20 bags would be £42.00 (+VAT).

Even with the delivery it worked out cheaper to order direct than from Travis locally and I'm reasonably confident the lime is fresher.

So I now have a couple of tons of sharp sand, 22 bags of Castle NHL5 and one of the hottest days of the year to start...

My builder pal has lent me a mixer and recommended adding some admix to help improve the workability of the mortar - does anyone have any idea if this is sensible with a lime mortar?

 

[AMc]

Hello Andy

These additives are designed to be used with cements and would have no effect on lime.

If you leave the mortar to stand for 30 minutes after mixing (out of the sun!), then this should help to fatten the mix up.

email response in less than half an hour -- very helpful supplier!

 

[Penners]

If you leave the mortar to stand for 30 minutes after mixing (out of the sun!), then this should help to fatten the mix up.

Judging by the clientele I saw at Stansted Airport yesterday, R**nair sandwiches should have much the same effect.

 

[skier-hughes]

yes, our lime guys mixed for ages and ages, left to stand for a good while and mixed for a good hour again.

 

[AMc]

yes, our lime guys mixed for ages and ages, left to stand for a good while and mixed for a good hour again.

Really? That's not good news I have 40m2 of patio to lay and I can only realistically work between 9.30-4 give myself an hour for clean up (mixer and me) then grab the kid from the childminder. Progress may be slower than I thought...will have to get the first mix on straight away.

 

[MdB]

I really wouldn't worry much for the job your are using it for.

 

[AMc]

Go on then - if you were to put a bucket of lime and 3 of sharp in - how much water would you want and how long would you mix for?

 

[MdB]

The right amount(*) and 15 to 20 minutes.

Others please correct if this is wrong..


(*) find this through experimentation. It depends on how damp your sand is.

 

[skier-hughes]

A good hour before resting it and then another 1/2 hour.

 

[Rudsdale Family]

Hello there,
Having been a tradesman for decades, in New Zealand, much of the advice given seems sound enough. We basically don't use Lime mixes at all as there is no call for them so I cannot elaborate further, sorry!
However, you can recycle your bricks, sand and gravel providing you Tamp the area with a machine used for that purpose, it must be at least a 100mm base to give a solid surface. Spray water over periodically while compacting and be patient, making sure your levels and falls are checked as you go.
You can now spread over this," Course river sand" or the equivalent you have in your area, up to at least 150mm and well moistened. Screed/level off, still checking your falls and levels and once you are satisfied, place your first stone working from one end to the other. I usually work on the stones I have laid, placing in front of me so as not to disturb the sand - you'll be surprised the number of people and trade who do not do this!
Finally, once you are satisfied with your work I would recommend that you, lay a bed of mortar around the edges of the stones to haunch them in place and then spread/sweep the course sand mix over the stones for the pointing. There is no need to lay them on a cement mix or mortar bed providing it is used for foot traffic only and you will find they can be easily be lifted if need be in the future. I hope this helps.

 

[Rudsdale Family]

Hello there,
Having been a tradesman for decades, in New Zealand, much of the advice given seems sound enough. We basically don't use Lime mixes at all as there is no call for them so I cannot elaborate further, sorry!
However, you can recycle your bricks, sand and gravel providing you Tamp the area with a machine used for that purpose, it must be at least a 100mm base to give a solid surface. Spray water over periodically while compacting and be patient, making sure your levels and falls are checked as you go.
You can now spread over this," Course river sand" or the equivalent you have in your area, up to at least 150mm and well moistened. Screed/level off, still checking your falls and levels and once you are satisfied, place your first stone working from one end to the other. I usually work on the stones I have laid, placing in front of me so as not to disturb the sand - you'll be surprised the number of people and trade who do not do this!
Finally, once you are satisfied with your work I would recommend that you, lay a bed of mortar around the edges of the stones to haunch them in place and then spread/sweep the course sand mix over the stones for the pointing. There is no need to lay them on a cement mix or mortar bed providing it is used for foot traffic only and you will find they can be easily be lifted if need be in the future. I hope this helps.

 

[AMc]

GRRRR How can it be 30C yesterday, all day when I'm labouring - go to bed with the thermostat reading 28C in the bedroom then wake up in the night to the sound of heavy rain?
The bags are moisture resistant and were covered albeit not well. Now I have to rearrange to use the bottom bags one of which has been splashed.