The Brew Cabin

Posted: **Thu Jun 02, 2005 10:34 pm**

I have just finished laying 45 sq m of natural indian sandstone and I am ready to grout. The average gap between slabs is 5-6mm but in certain cases it can vary from 0-15mm due to the irregular edge of the slabs. Before I start I would like some advice on which method to use for grouting:

1. I am contemplating the use of polymeric sand because it is the right colour but I am concerned that manufacturers specify a minimum gap of 5mm. While most of the gaps adhere to the specification some are too narrow and I am concerned that the sand will not bond properly in narrow gaps. Do the quarry fettled edges negate the need for a 5mm gap on the surface given that the gap widens significantly beneath the slab? Any advice? Will it work?

2. Option 2 is dry grouting which I think will be better since it will bond to the slabs (unlike the polymeric sand) but the colour is inconsistent with the light yellow colour of the salbs. Is there a way to dye/colour the dry grout in a yellow colour suitable for indian sandstone?

Please advise.

Posted: **Fri Jun 03, 2005 9:13 pm**

Polymeric sands have highly variable results. If you browse through the older posts, you'll notice not many people have enjoyed their experiences with GeoFix, which bonds only to itself and not the paving, but recenntly, I've been dabbling with Rompox and found it to be excellent for setts and flagstones with slightly wider joints (7-20mm sort of thing) I've not tried it in narrow joints, but I suspect it could be problematic because the grain size is relatively large.

Sika and Cementone have polymeric agents newly released onto the market, but, as yet, I've not had a chance to assess them. Yesterday, I was chatting with another manufacturer (Nufins) who reckons their sealant product can be used in conjunction with plain kiln-dried jointing sand to give a firm and permanent joint. More on this in the coming weeks, hopefully.

Dry grouting is all but imnpossible to colour. The dye/pigment requires moisture to activate its colouring powers, and there's no moisture ion a dry grout, so you get no colour. Some people have reported success in using a pigmented dry grout that is wetted once in the joint. I haven't tried this, so I can't comment, but it might be worth a try.

I wouldn't get to concerned about the colour of the mortar/grout. In 12 months time, it will either be light or dark. You might just be able to tell it's buff, or pink, or marigold, or whatever, but it will need regular cleaning to keep the colour evident.

I still think the method outlined on the website, using a semi-dry mortar pushed into the joints, is by far the most successful method. If you can't face all that work, then the polymeric option might be simplest for you.

I'd be interested to hear which route you follow, and how it works out for you.

Posted: **Sat Jun 04, 2005 6:35 pm**

If choosing Geofix based on it being 'the right colour' then would not bother, within a few months or less, it tends to turn dark green / black with algae growth
Looks great to start with though!
Not yet familiar with other products Tony mentioned, so can't comment on these.

The Brew Cabin

Grouting gaps - Grouting natural indian sandstone