I've heard these called 'Benton Blocks', though, looking that up now, that seems to be a brand [0], not sure if there's a more specific generic term other than 'concrete block'.
> Somewhat related: The famed "Jersey Divider" is cast in a similar way, albeit without any consideration for vertical stacking.
I think Jersey Barriers are usually re-enforced with steel rebar and all the ones that I've seen have a steel cable running through them with a loop at either end to link up to the one next to it, by dropping a pole or similar through both sets of loops, to create a continuous wall. (Though, interestingly, the Wikipedia article [1] doesn't seem to mention that feature.)
[0] https://betonblockusa.com/us/products/concrete-blocks [1] https://en.wikipedia.org/wiki/Jersey_barrier