108-year-old core sample from Indianapolis Motor Speedway track - photo

[Ralphxyz]

Thanks Frank, it's interesting the major crack that they centered on when they took the sample looks like it might have started at the very first, top pictured, layer.

Ralph

[Frank S]

Thanks Frank, it's interesting the major crack that they centered on when they took the sample looks like it might have started at the very first, top pictured, layer.

Ralph

Ralph, core samples can only create a snapshot of things below. Cracks in road surfaces rarely ever start from the top without some underlying fault which lends to their being.
If you note in the picture that Jon first posted you can see a crack down below in the brick an d one at the top in the top layer, but there appears that there is no crack in ht every middle layer. However what we can not see is the length of the crack. Since paving materials other than concrete or mortared together brick retain some semblance of elasticity just not consistently some areas will stretch while others will separate. also cracks rarely ever run true linear in a straight line so we may not be able to see the crack due to it being either more towards the center of the core sample or even possibly to the outside of the sample