Abstract: A low density annular grout composition for filling voids. The composition may consist of cementitious fly ash, water, set retarder and cellular foam. The composition may have a compressive strength of between 100 and 600 psi at seven days and less than 1500 psi at 28 days. The composition may have a density between 20 and 75 pcf. Also disclosed is a method of filling a void with a low density annular grout composition. The method can include determining the time necessary to fill the void, adding water and set retarder to a cementitious fly ash to make a wet mixture, adding air to the wet mixture, and adding the composition to the void.

Abstract: A composition and method for reducing freeze-thaw heave risk over flash-filled voids are disclosed. A composition can include cementitious fly ash, water and cellular foam. The composition can optionally include a filler, e.g., Type F fly ash, or additional desired components. A method can include mixing the desired composition and applying the composition to a void. The method can optionally include determining the desired composition based on various factors.

Abstract: Systems and methods for filling submerged voids with a foam-fluidized fill material in an efficient and economical manner are disclosed herein. The foam fluidized fill material is a granular solid material fluidized with a foam. The foam-fluidized fill material is pumped or gravity-fed through an insertion tube into the submerged void. The insertion tube terminates at a point lying below a surface of the liquid within the void. Since the foam-fluidized fill material is heavier than the liquid, the foam-fluidized fill material exiting the insertion tube sinks to the bottom of the void and expands laterally at the bottom of the void displacing the liquid. The liquid is forced upward and out of the void where it may be collected. Further, as the fill material fills the void, the foam dissipates and the fill material self compacts, making the filled void sufficiently load bearing.