I am building a fire pit in my backyard. I have poured a 6 inch thick concrete foundation and want to install concrete pavers on top of the concrete base. I have been unable to find any recommendations for the best type mortar to use. What type mortar should be used for laying concrete pavers on a new concrete patio?
No Mortar for the pavers, you'd lay the pavers on a 1/2" to 1" bed of sand & sweep either that same sand or the below special Perma-Sand into the paver joints. This, allows for the constant movement & drainage. Mortared or not you'll need a perimeter retainer of, at least, 1/2" tall.
If you insist on Mortaring the pavers, & having cracks, then use a Type-S Mortar, this would also be used for the Fire Pit's red or decorative brick. The Fire Pit needs a Fire Brick interior Mortared with High Heat Cement.