How to merge particles together? (get rid of fractures)

[Alexx31]

Hello,
a basic question:
How can I merge particles together? I tried "Element Attache" or "Weld" but nothing happens.

I need some fractures to delete parts of a mesh, but then I want it again to be "fresh" and without any prefracturing.
(Because these fractures also wouldn't look good in this case)

Thanks