What type of sand for between paving slabs after power washing

Hi,
The Mrs took her frustration out on the dirty patio paving slabs with the power washer. Especially along the side of the patio where it meets with a concrete fence, there are wide open gaps of where presumably sand, soil, moss where before she took them out.

Any particular sand I should get to brush between the existing slabs and any gaps bordering the fence.
Slabs are light coloured so get dirty quickly

Thanks

 

When my drive was done they used kiln dried paving sand with weed inhibitor - I had no weeds between the slabs for 3 years

 

About 20 yrs ago I laid some block paving, I used a PU based filler that you swept into the cracks, it then set by moisture but still allowed movement.

Not sure what it was now but I think I got it from Wickes.

 

Something similar to this.
Sika FastFix All Weather Charcoal Paving Jointing Compound - 15kg | Wickes.co.uk
It comes in different colours.

 

Be warned, that stuff has to be tamped down pretty hard into the gaps before letting it set (or even applying watering can). So edge of builder's trowel is favourite. And if you don't use it all at once, I think it has to be kept under water once you've opened it. (Check though - I may be imagining!)

 

Well I tended to just brush it into the gaps, its funny stuff that seemed to be on the move itself but difficult to explain.
It may not be exactly the stuff I used as the stuff I had used the dampness to set it, keeping it under water would have presumably set it solid.
My stuff was a polyurethane type product, I just thought this was similar.

 

Yes, there are all sorts of newer products. We used one on a job last year. It works well but the gaps need to be wide enough to get enough in to bond. If someone has done a very narrow grout line, it's harder.

 

If you're going to keep power washing them, then a dry mix [sand and cement] brushed into the spaces is a better option. You can buy it ready mixed. After brushing it in [it takes a while to do it properly] lightly water it with a watering can with a fine rose attached, and make sure there's none left on the slabs themselves. Make sure there's no heavy rain in the forecast. It'll set quickly though.
We always did that with any paving that was laid, to ensure stability, and to save any future problems with weeds etc.

 

Thanks all for your replies.

In terms of power washing regularly, I would say maybe only once a year, two at most.

Most of the gaps between the slabs are very narrow (circa. less than half a cm so even less than 5mm). I feel for these narrow gaps, the kiln dried sand would be better on the assumption it will get between the gaps easier whereas any cement sand mix may struggle to get between the gaps, unless I’m wrong?

For the bigger gaps at the edge of the patio, where the slab is bordering the concrete fence panel, I do think a cement sand mix would do a better longer term job. Some of those cement mixes seem expensive especially if only using a small bit.

Pics attached for reference

 

I can't see that the smaller gaps actually need anything doing to them. If you just use sand it will wash out every time you power wash it anyway.

 

They possibly don’t but there was a lot of debris that came out of the patio during the power washing, albeit more towards where it bordered with the fence panel However, I guess for the smaller gaps it was more about topping it up, if a sensible approach.