Dear Tony,
I've recently completed a gravel drive in which I edged the front of the drive with a single soldier course of Tegula Drivesett blocks(which run adjacent to the pavement). I laid these blocks on a concrete bed (6 to1 mix) approximately 4 inches thick. I didn't haunch the back edge of the blocks(gravel side) with concrete as the house owner is considering having the whole drive blocked in the future. With this in mind do you think there's any likelihood of blocks coming loose as a result of vehicles driving across them? Hope all this makes sense.
Regards
Gary
They might come loose, but it's easy enough to fix them if they do. I'd have added a token haunch, just to be safe, and then accept that I'm going to have to spend 10 mins next year chiselling it out to accommodate the new paving.
It's hard to say. Normally, if there was any suspect bedding or potentially loose blocks, they'd show up in the first couple of weeks, but occasionally, you get one of two blocks that seem fine and then, 6 months later, they suddenly flick out for no apparent reason.