I was digging a trench next to a building today so rain water would not back up to the buildings wall. Most of the material was soil but there were some large chunks of concrete. The largest chunk of concrete that was too heavy to move was pryed up and supported on the left and right sides with smaller stones as well as being supported by the ground. The idea was to beat the concrete in the middle with a sledge hammer and break it into smaller pieces. About a half to an inch layer of damp dirt lay on the top of the concrete. I swung a 20 pound sledge hammer with good effort and did little to the concrete but I compressed the dirt to such an extent that the dirt seemed to turn into a liquid and splattered with great velocity in a narrow fan shaped jets whose velocity was mostly perpendicular to the sledge velocity just before impact. After the shock of being sprayed by high velocity dirt wore off, subsequent blows to the concrete broke it up. Was the damp dirt changed into a liquid like material by the hammer blow? If the dirt were dry I don't think the same effect would have occurred (unless under much higher pressures?) Thanks for any help!