Not a marital aid, and not explicitly home repair, I'm looking for a quarry
workers tool.
I need to break up a large irregular chunk of concrete (maybe 4x5x2 ft) and
I saw a technique on TOH some years ago for splitting granite - called (I
think) plug and feather.

It involves a line of holes drilled, and a series of devices hammered into
each, simultaneously. the devices, a pair of L shaped 'feathers' surrounding
a tapered steel 'plug'

Anyone ever heard of a source for these devices?

The concrete is probably very hard, having cured at the water's edge,
semi-submerged.

Any source - or better idea - would be MOST appreciated.

Many TIA.

MF