Mortar mix for terracotta floor tiles?

[michael]

I have a small concrete ramped area outside my back door about a meter square which I wish to tile over with a few left over 6” terracotta floor tiles. These are plain unglazed terracotta tiles about 20mm thick that have been treated with multiple coats of double boiled linseed oil (Leftovers from an old bathroom floor project). I also have about half a bag of left over NHL3.5 which I would like to use up. Would this lime be suitable for laying and pointing the tiles? I need to achieve 10mm wide pointing in a similar fashion to brickwork.
Because this could really be described as a ground works project, I’m guessing that NHL 5 would probably be more suitable, but being a bit of a miser, I would like to use up what I’ve got. The ramp is in quite a protected position with walls on two sides and a roof overhang and it has a slight fall away from the back door so it should never become totally saturated, nevertheless, I want to use the lime to protect the tiles from any potential water ingress and frost. I do however need to consider the strength of the mortar with regard to withstanding foot traffic. Do you think I can get away with the 3.5?

 

[michael]

This one seems to be baffling everybody. I guess the questions when stripped down are: –

(a)Can NHL3.5 be used as an exterior floor tile or paver adhesive and grouting or must it be NHL 5 or other?
(b)Is NHL 3.5 strong enough for light foot traffic when used in this context?

 

[plasticpigeon]

My 2 pence worth is that perhaps unglazed quarries are not great for outside, I have seen them spall badly in the frost. Since the ramp is concrete, what could be gained by using lime? I know this answer is not very good as I haven't answered either of your questions!!!

 

[tobydog]

I went to Anglia Lime a couple of weeks back. Apart from picking up three tubs of putty (only needed one but couldn't resist at £14 for 20kg tubs) I also discussed with them that I needed to fill the large gaps between my old soft brick garden path that are currently all full of soil and weeds (very slippery when wet). I asked if NHL 3.5 would work and they thought it should be fine. During our building works the builder had to cut through the path twice to put the oil line in and they reset the bricks in cement. Much more grip in these places but looks a bit grey. Hopefully 3.5 will look softer and blend in better.