Restoring cobblestoned streets?

After much procastination, in the last couple of years the city council Heritage office along with the MINVU office using state grants and a BID heritage loan have been replacing the old cobblestones and stone setts from the port area with new ones.
Earlier on, the original cobblestones rested on a sandy bed and, it was just shear gravity that bedded them together. Many of the older cobblestones were later replaced by setts and are still resting covered now by tar or asphalt pavement that just recently have been opened again to restore the old streets. This time, most of the older cobblestones and stone setts have been replaced by new setts glued by 1/3 mortar resting on a new concret bed. For this work new smaller sized grey and pink volcanic rock setts from Colina (Santiago) are being used.
These smaller stone setts should generate a larger infiltrating area to improve the quality of permeable paving of the original cobblestone paving. Nevertheless, the use of heavy mortar and a concrete underbed foretells future drainage and cracking trouble especially in the area of the flats (plan) next to the surrounding slopes of the hilly neighbourhoods of town.