|
That does help, thank you. I read over the other related threads and that, too, was helpful.
Today we learned that the concrete base under the walkway is 6" thick and was poured over a crushed type of stone (black and very porous and light). Most of the flagstones we removed today were dry-laid on 1 to 4" of course sand, but some were on top of 1 to 2" of mortar on top of 1 to 2" of course sand (sand composed of particles up to 1/3rd inch). Still others (a minority) are properly mortared to the base. It is an amazing sight to behold.
In essence now we have a strong base that is about 50% flat and 50% with an "undulating" surface due to the strange construction techniques. The undulations are composed of what I assume was used as mortar - it is strong as stone but there is no large gravel in it. Basically our mortar layer under the flags will be 1 to 4" thick when we lay over the existing base. What do think of cutting grooves with a chop saw every inch or so to increase the holding power of the new mortar?
|