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: Implementations described and claimed herein provide a process for creating a high-carbon cellular concrete that may include high-carbon ash, cement, water, and surfactants to produce a high-carbon cellular concrete. The high-carbon cellular concrete wet mix maintains its cellular properties while it is placed and cures. Also, because of the gelling characteristics and viscosity of the cellular concrete wet mix, it may be placed in a manner that requires fewer lifts or stages in a placement, which may reduce time and expense. Further, the cellular concrete wet mix may travel laterally during placement without losing its cellular matrix of micro-bubbles before curing.

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.

Abstract: A composition for treating an excavation activity includes a reagent suspended in foam to form a reagent-foam mixture. The reagent is selected to react with at least one of sulfides or bacteria in waste rock or tailings materials to reduce acid rock drainage. The reagent includes at least one of limestone, dolomite, sodium bicarbonate, steel slag, fly ash, or sodium hydroxide.

Abstract: A system for treating an excavation activity includes a distribution network in fluid communication with the excavation activity. A foaming agent and a reagent are supplied to the distribution network to form a reagent-foam mixture. The reagent is selected to react with at least one of sulfides, bacteria, or heavy metals or to coat particulate materials. A method for treating an excavation activity includes flowing a foam through a distribution network in fluid communication with the excavation activity and selecting a reagent to react with at least one of sulfides, bacteria, or heavy metals or to coat particulate materials. The method fluffier includes mixing the reagent with the foam flowing through the distribution network to form a reagent-foam mixture and dispersing the foam-reagent mixture over at least a portion of the excavation deposit.

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.