Here you go,
After much debate (some heated I'll come to that in a minute), this is how we do it.
4 parts sharp sand
1 part
hydrolic Lime
Approx 3% white
cement (we put this in to ensure some solidity in the bedding)
Mix the sharp sand and the lime and the white
cement to a semi dry mix and bed down hard. Then sprinkle over with water from the watering can.
The important bit is this, make sure the back of the stone has been covered with wet lime slurry or you won't get the adhesion to the bedding.
Ensure that the bed is solid, and the stone is well bedded, if you dont your going to know about it a few months down the line.
Also an important factor is the temp, it is notoriously difficult to get it to set off in cold weather,
I have to throw this in, you said the architect is stated hydrated lime, well unless you have 6 months to sit around waiting for the bedding mix to go off then its all good, but you havent. You need to clear this with them and get this point across. Hydrated = no Hydrolic =yes?
Let us know how you get on.
Lynn