Heated bench advice

We have recently moved and have inherited a wonderful garden and greenhouse with heated bench. The material on the bench is very compacted, almost like a cement, should it be loose, more like a gravelly texture? I’ve hacked at it to a depth of about 2/3 inches and found a thin fleece type material under which I assume is the cable buried in sand. Should I water and hack at it until it crumbles?! (Easy enough to do once water soaked into it I discovered) Thanks