The invention provides compositions and methods for sealing subterranean spaces such as natural or induced fractures, vugs or annular spaces. The composition is composed of a base fluid consisting of a soluble alkali silicate, a gas generating additive, solids and a setting agent. The gas generating additive may be coated or uncoated. The gas generating additive may also be in the form of a slurry. In the case of coated additives, the coating may act as a retarder or an accelerator to the expansion and setting agent of the soluble alkali silica. Similarly, the choice of carrier fluid in a slurry may retard or accelerate the expansion and setting of the alkali silicate-based plug.

A composition for use in a method or a system to stabilise a material such as geological strata or a rock mass in which initially retarded gypsum is accelerated at the time of introduction or injection into the rock mass. The retarding of the gypsum may be accomplished by a retarder such as a hydration inhibitor mixed with the gypsum and the acceleration may be accomplished by an accelerant added to mixture of the gypsum and retarder. Upon introduction of the accelerant, water is also added to initially reduce the viscosity of the composition so as to be less than the initially retarded gypsum so as to make it more easily pumpable before becoming set within the geological strata or a rock mass.

A composition in the form of a backfill is described. The composition comprises one or more mine tailings present in an amount greater than 50% by weight of the composition, one or more cementitious binder materials present in an amount ranging from 0% to 12% by weight of the composition, attapulgite present in an amount ranging from 0.01% to 4.00% by weight of the composition, and water. The fines content (Fc) of the one or more mine tailings is greater than or equal to 3%. Although subject to many uses, in some embodiments, the composition is suitable for managing tailings to be stored above ground or underground. For example, in some embodiments, the composition is suitable for filling mined out areas.

Mining provides our society with many of minerals, metals, and gemstones for a wide variety of applications from mundane items through to expensive jewelry. But the mining operations generate waste and large empty shafts and stopes within the ground. It would beneficial to provide a lightweight material for backfill which can provide safer working conditions for miners as well as advantages in respect of weight reduction, reducing water consumption, rheology improvement and cost minimization. Equally, it would be beneficial for the lightweight backfill material to include mining tailings to reduce the impact external to the mine. However, the inclusion of mine tailings into a foam is counter-intuitive as mine tailings are generally characterized by a high proportion of small particles with sharp edges. However, embodiments of the invention provide just such a foam based mine backfill material.

A process of preparing a cemented paste backfill material, the material including ground mine tailings, a hydraulic binder and water, wherein the solids content of the backfill material is 70-82 wt.-%, the process including a) providing a dry premix, the premix including the hydraulic binder, a superplasticizer and optionally a defoaming agent, b) mixing the dry premix with the ground mine tailings and water.

A concrete, mortar or grout formulation comprises two separate components: a concrete admixture comprising: (a) a concrete mixture; (b) alkali carbonate; (c) aretarder; and (d) water, an accelerator mixture comprising: (a) anaccelerator component; and (b) water.

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.

A composition configured to be mixed with cement, and associated systems and methods are disclosed herein. In some embodiments, the composition includes at least 10% by weight lime particles, and at least 35% by weight pozzolan particles. Properties of the composition can include a magnesium oxide concentration of at least 0.5%, and an iron oxide concentration of at least 0.5-2.0%, an aluminum oxide concentration of 2-8%, a silicon dioxide concentration of 20-40%, a potassium oxide concentration of 20,000-30,000 ppm, and a sodium oxide concentration of 10,000-20,000 ppm. In some embodiments, the lime-based cement extender composition, or product, is combined with cement to produce a cement blend for use in the mining industry as mine backfill.

Fast-setting flowable fill compositions for filling ground trenches are described. The compositions set quickly but retain a low strength psi at 28 days. The compositions also reduce bleed water on the surface of the fast-setting flowable fill and therefor enable quicker application of surface repair material, e.g., pavement patches, to the trench. The compositions consist of aggregate, Portland cement, accelerant, water and sometimes air. The compositions may have a compressive strength of between 5 psi and 60 psi after 2 hours, a compressive strength of between 10 psi and 100 psi after 4 hours, a compressive strength of between 75 psi and 500 psi after 28 days, a penetration resistance of between 1.5 tsf and 75 tsf after 2 hours, a penetration resistance of between 4.5 tsf and 200 tsf after 4 hours, and a shrinkage of less than 2% as measured by ASTM C490. Also disclosed are methods of filling a trench with fast-setting flowable fill.

A method for sealing of surfaces comprising the steps of: (a) supplying a first grouting composition; (b) introducing a second component to said first grouting composition to form a third grouting composition; and (c) forming a sealing barrier on a surface from said third grouting composition.