Anyone knowledgeable about cement between slate pavers?

[fluff48]

Hi there

We have large pieces of slate (between 2-4” depth in places) which we have pieced together to make a small patio. But there are gaps between them as they are random shapes, ranging from a small 1” gap to about 3-4” in other areas.

Anyone know what would be best to fill the gaps with to prevent our chair/table falling in the gap?

We were thinking putting some chippy stones in as a base layer then cement on top.

If this would be best practice, does anyone know the ratio of cement to sand?

Thanks for any advice you can give.

Cheers
Fluff

[Mr Tom Morrow]

The general rule of thumb is 3 sand to 1 cement. The more the sand the stronger it is but it must be well mixed. If you for example did a 4 to 1 and it wasn't thoroughly mixed it will crumble as it is too sandy.

Some builder will say 2 to 1 but I prefer 3 to 1.

As you say for the huge gaps get a load of chippings in first as they will make it stronger.

[fluff48]

Thank you so much Mr T, I was hoping you would know. Is sharp or building sand better?

I also have left over kiln dried sand from last week between the monoblock. Would that be ok?

[Mr Tom Morrow]

I never use B & Q but always like Blue Circle Portland General Purpose cement and normal builders sand.

Edit. No the kiln dried sand is too fine sorry.

[fluff48]

Brill, thanks.

Is this the stuff?
diy/departments/blue...g/35715_BQ.prd

[Mr Tom Morrow]

Originally Posted by fluff48

Brill, thanks.

Is this the stuff?
diy/departments/blue...g/35715_BQ.prd

See more...

That’s it.. wow expensive but a convenient size I suppose. Better discounts if you buy more but that’s not necessary for your job I suspect.

[cornishfrogboy]

I agree with Mr M on the 3-1, but always add in some plasticiser also.

Some may talk of dry mix, pour in and then wet with a watering can.. or even wait for overnight dew. I have found this extremely hit and miss. I would not recommend it.

Also remember that having filled your gaps, there will in probability be some cement on your tiles that may result in a cementy, washy, unsightly appearance. Carefully sponge this off, using multiple applications and squeeze outs of the sponge into a bucket of water. Too much water will seep into your cement pointing and then weaken it.

Hope it helps.

[Mr Tom Morrow]

For 'normal' size pointing my neighbour used this.

Really good gear and the best I have seen.

screwfix/p/sika-fast...rey-14kg/539fy

[fluff48]

Back from B&Q with a bag of cement & 2 bags of building sand from wickes (no sand at B&Q)😩.

Do I need the plasticiser? Does it stop the cement cracking or something else?

Edit: just read it makes it easier to mix so I can add less water, is that right? How much to I add if using 3:1 sand to cement

Will this do? toolstation/everbuil...SABEgL4sPD_BwE
Or this? toolstation/febmix-a...ticiser/p45220

I would like to use it again when we fix some mortar verges, once we attempt this first.

Cheers

[fluff48]

Originally Posted by Mr Tom Morrow

For 'normal' size pointing my neighbour used this.

Really good gear and the best I have seen.

screwfix/p/sika-fast...rey-14kg/539fy

See more...

I think I will need more than that. Some gaps are quite wide/deep 😩