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Posted: Sun Jan 17, 2010 4:36 pm
by dr benway
Greetings!
long time lurker, first time poster.
I was reading up about romex/rompox and saw that it is water permeable.
how does this work with [say] sandstone flags on full mortar beds, in freezing conditions?
Thanks!
Posted: Sun Jan 17, 2010 10:24 pm
by lutonlagerlout
i wouldn't say its water permeable to the extent that water gets through it easily
I think that in general water runs off it rather than through it
the cold has had no noticeable effect on my romex
LLL
Posted: Mon Jan 18, 2010 9:15 am
by dr benway
lutonlagerlout wrote:i wouldn't say its water permeable to the extent that water gets through it easily
I think that in general water runs off it rather than through it
the cold has had no noticeable effect on my romex
LLL
thanks for the reply. this was what I'd thought but then I read this in the romex leaflet, so i was a bit confused...
http://www.pavingexpert.com/pdf/romex_easy_07.pdf
"Rompox - Easy is a highly water permeable pavement fixing mortar that allows almost all quantities of rainwater to seep into the ground. Due to the open porous structure of ROMPOX - EASY, all the requirements for a water permeable and thus environmentally friendly fixing mortar are fulfilled. Ideal for natural paving."
Posted: Tue Jan 19, 2010 3:36 pm
by Tony McC
The jointing *is* water permeable (incredibly so, actually) but it needs a permeable bed if it's to allow water to drain through the pavement, otherwise the joint just "fills up" with water that has nowhere to go, and so it can appear to be impermeable.
Posted: Tue Jan 19, 2010 4:52 pm
by Bob_A
So if the bed is impervious the Rompox would soak up water but there wouldn't be anywhere for it to go.
Could that cause with freeze/thaw?
Posted: Tue Jan 19, 2010 4:52 pm
by lutonlagerlout
well if the paving is laid on the standard full mortar bed ,then the bedding layer is nigh on impermeable?
I cant think of a bedding layer that would be permeable to any great extent, apart from grit or recycled glass ,but they wouldn't be right for flags/slabs would they?
food for thought
LLL
Posted: Tue Jan 19, 2010 5:00 pm
by dr benway
edit* oops-- that'll teach me to make a cup of tea mid post!
thanks for the reply. [and all the great info here-- very much appreciated!]
if it "holds" water, then is it susceptible to freeze/thaw action?
or I suppose what I'm asking is which product would you use to point indian sandstone-- just for residential patio type use?
thanks again
Posted: Tue Jan 19, 2010 6:36 pm
by Tony McC
The adhesive strength of Romex is so high that the sort of frosts we get in Britain and Ireland will have no impact. The stuff is manufactured and tested in Germany, where they have man-size frosts, for months at a time some years, and the jointing survives, apparently.
Any expansion of water within the joint that occurs during a freeze episode displaces water upwards and out of the joints without compromising the pavement.
And to answer LLL's point about the permeability of bedding, it *is* possible to create permeable laying courses. I've designed a selection for various clients looking to create permeable pavements for all sorts of reasons. It's simpler than you think!
Posted: Tue Jan 19, 2010 8:52 pm
by lutonlagerlout
anyway dr.benway, mine has been down 3 years and is still fine
you have the grey matter working overtime now boss, how can a bedding layer be permeable??? hmmmm
no fines mix perhaps?
some expensive gftksbrromexronamillion product??
one thing i have noticed dr.benway is the romex discolours with general dirt etc
but the old jetwasher soon gets it looking pristine again
courtesy of RA pressure washing 
LLL
Posted: Wed Jan 20, 2010 12:46 pm
by dr benway
Tony McC wrote:Any expansion of water within the joint that occurs during a freeze episode displaces water upwards and out of the joints without compromising the pavement.
thanks for the replies
I can see how the romex itself will resist frost/freeze, but what happens to the water that goes through the romex, surely it will find even the smallest voids underneath?
how permeable is "ordinary" mortar pointing?
I also read the spec sheets for vdw, and the heavy duty, 2 part is 5 times more permeable than the pre-mixed.
thanks