Joined: July 2004
||Posted: 11 Dec. 2019,20:48
This is becoming a bigger and bigger problem. Nearly all of the resin mortar suppliers, whether it's 1-part or 2-part, are stating the need for permeable bedding, but the most common laying method in Britain and Ireland is on a practically impermeable mortar bed. How can this be reconciled?
In short, it can't, but the insistence on permeable bedding hails from Germany, where the better mortars originate and where there is far more genuine research into pavement structure than ever takes place in Britain (or Ireland), and where the use of permeable bedding (trass bedding) is practically standard practice. These resin mortars are designed to provide optimum performance with permeable bedding.
However, they can, and should, provide a reasonable level of performance when used with impermeable bedding, as explained on this page.
Admittedly, it's less than ideal, but a genuinely good 2-part mortar will give a more-than-acceptable level of service when installed correctly. Yes: they are engineered for German and other North European pavements rather than the fickle, finicky and haphazard British/Irish market, but the better products simply do not fail in permanently wet conditions.
Worryingly, some of the less impressive resin mortar suppliers are now latching-on to this lack of permeability in the bedding as an escape clause for the poorer performance of their products. It's far too tempting for bewildered reps to throw their hands in the air and claim, "It's that crap bedding" when there's a failure of the jointing they gladly sold without ever really mentioning this potential problem.
The sooner we take up trass bedding as the default bedding for ALL of our paving, the better, as far as I can see!
Site Agent - Pavingexpert