Abstract: A roof support column used as a support between the roof and floor of a mine comprises a stacked series of hollow roof support cribs containing a mixture of light-weight aggregate such as volcanic lava, tuft or pumice, and a chemical foam contained in one chamber of a triple-walled high density paper tubing. The other chamber has honeycomb material therein. The combination of these materials results in a roof support crib which has the yielding characteristics of wood. Such cribs called variable yielding cribs are stacked and locked on top of one another to form a vertical cylindrical cribbing support column.

Abstract: A roof support column used as a support between the roof and floor of a mine comprises a stacked series of hollow roof support cribs containing a mixture of light-weight aggregate such as volcanic lava, tuft, or pumice, and a chemical foam contained in a double-walled high density paper tubing. The combination of these materials results in a roof support crib which has the yielding characteristics of wood. Such cribs called variable yielding cribs are stacked and locked on top of one another to form a vertical cylindrical cribbing support column.