Maybe not the most desirable option but could you make up some stainless flat bar straps and set 2 anchor bolts on each side of the center joint? You can get anchor bolts that use screws instead of nuts that are relatively flat. They would run the length of the driveway and be located in the center.
I wondered About doing something like that but am concerned it may cause stress cracking around the bolts and result in a bigger mess
