[HayZee518]

It certainly looks like the northern most waters have taken their toll on your pavers! Flagstone used for a deck usually are embedded in sand and tamped into place. the voids are filled in using sand and the rest is swept away. With mortar mix being used, the concrete shrinks as it cures and water , like we get up north, freezes and expands causing voids between the pavers, eventually crumbling. what you might try is first of all remove all the concrete from between the pavers. next make up a mix consisting of three parts portland cement and five parts sand. use enough water to make a semi dry mix - not sloshy like regular cement. Apply this mix in between the pavers and tamp down using a mallet and pieces of wood or steel bar in the voids. this is the same mix used to create a sub-floor in a shower stall - it never really dries out but is hard to the touch. maybe this will work for your foyer.