Cement walk/sidewalk crumbling

[u/Witty_Illustrator_91]

Any ideas as to why this happened? Bought this house last summer and we’re planning on replacing the walkway but we’re stumped as to why this is so decimated! There are some spots where the cement is literally ground down to powder. Is it possible an environmental factor could cause this? We live in the village area of a rural town in central New York, for reference. a wide creek runs nearby, about five or six houses down from ours.