A vinyl alcohol-based polymer useful as an additive for oil well cement is provided. The vinyl alcohol-based polymer is produced by saponification of a homopolymer of a vinyl ester monomer or a copolymer of a vinyl ester monomer and a polyfunctional monomer, wherein the vinyl alcohol-based polymer has a difference between transmittance (A) of 1 mass % aqueous solution at 660 nm and transmittance (B) of 1 mass % aqueous solution at 430 nm, i.e. (A-B), of 5 to 25. It is preferable that 1 mass % aqueous solution of the vinyl alcohol-based polymer have a transmittance of 95% or less in an entire wavelength region of 200 nm to 800 nm, and the vinyl alcohol-based polymer have a yellow index of 10 or less.

A high-strength Portland cement slurry for ultra-high-temperature cementing, a preparation method therefor and an application thereof. In parts by weight, the composition of the cement slurry comprises: 100 parts of Portland cement, 4-6 parts of a high temperature anti-cracking material, 80-105 parts of a high-temperature reinforcing material, 70-78 parts of water, 0.5-1.5 parts of a dispersant, 1-3 parts of a fluid loss reducer, 0.5-2.5 parts of a retarder and 0.2-0.5 parts of a defoamer; the high-temperature reinforcing material is a combination of acid-washed quartz sand, metakaolin and aluminum sulfate, a combination of acid-washed quartz sand, metakaolin, feldspar and sodium sulfate, or a combination of acid-washed quartz sand, metakaolin, feldspar and calcium nitrite. The cement slurry has good settling stability, rapid strength development in low temperatures, high compressive strength of cement stone at a high temperature of 600° C., and stable development of long-term high-temperature compressive strength.

A method for ecological filling with mixed coal gangue and fly ash includes the following steps: S1: construction of a double-impermeable base layer: leveling a pit or gully, laying a fly ash-based cementitious material, compacting and curing; spraying a layer of polymer waterproof coating on a surface of the fly ash-based cementitious material, and fully curing to obtain a double-impermeable protective structure; S2: three-dimensional layered filling: dumping coal gangue and fly ash in sequence on the double-impermeable protective structure formed in S1, where the coal gangue and the fly ash are three-dimensionally layered and well graded; the coal gangue is coal gangue after coal washing, which is used as an aggregate; the fly ash is used as a filler and cementitious material to achieve a compact filling structure; and S3: rolling: rolling by a roller after the three-dimensional layered filling.

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.

Disclosed are a fireproof material, a fireproof plate, a fireproof wall structure for tunnels and a construction method. The fireproof material includes the following components in weight ratio: 20-35 parts of aluminosilicate; 10-25 parts of calcium carbonate; 5-15 parts of magnesium oxide; 5-15 parts of silica; 20-40 parts of a binder; and 5-10 parts of a curing agent, the binder includes at least one of lithium silicate, potassium silicate and sodium silicate in combination with at least one of quartz sand and industrial sugar; and the curing agent is at least one of lithium oxide and magnesium oxide. In the preparation, firstly forming the mixture of aluminosilicate, magnesium oxide and silica into particles at 900° C.-1250° C., and then mixing the particles with calcium carbonate, the binder and the curing agent, and then pouring same into a forming mold and heating and pressing to form the fireproof material.

A controlled low strength material has constituents that include a cement, an aggregate, a heavy oil fly ash, and a water. The controlled low strength material has a compressive strength in a range of 300 kPa to 2.1 MPa. In certain embodiments, the heavy oil fly ash can be part of a heavy oil fly ash slurry.

A hydrogel forming composition comprising at least one water-soluble (meth)acrylic compound, at least one free radical initiator, at least one catalyst for free radical formation, and water, wherein the at least one catalyst for free radical formation is an amine compound of formula (I). The invention is also directed to a multiple-component composition, to a hydrogel, to use of the hydrogel forming composition for sealing of constructions, tunnels, or mines or for soil stabilization, to a method for sealing and/or filling of cracks, voids, flaws and cavities in a building structure, and to a use of at least one tertiary amine compound for reducing the gelling time of a hydrogel forming mixture.

A full-length screen pipe hole protection device and method with pressurized hole packing in a soft coal seam relates to the field of gas drainage technologies. The device includes a grouting system, a drainage system and a hole fixing system. The grouting system injects a pressurized sealing material into a borehole through a pressure pump to increase a sealing effect of the borehole. The drainage system drains gas in the middle of air holes on metal baffle plates and hole fixing screen pipes through a drainage pipe to increase flowability of gas. The hole fixing system is inside the borehole and fixed with the metal baffle plates, and the hole fixing screen pipes are fixedly connected with each other through fitting mouths and fitting buckles. The device is fixedly mounted in the gas drainage borehole. After hole packing, the drainage pipe is connected with a drainage pump to drain gas.

High-strength flowable fill compositions are disclosed. The compositions include cement, aggregate (e.g. sand), water, coloring agent, polymer, and fibers. In an embodiment, the compositions include an accelerant, e.g., calcium chloride or sodium bicarbonate and/or an air entraining agent. In an embodiment, the compositions include a water-proofing agent to eliminate efflorescence. The compositions have a compressive strength of between 300 psi and 3000 psi after 1 day, a compressive strength of between 900 psi and 4000 psi after 7 days, and a compressive strength of between 1200 psi and 5000 psi after 28 days.

A method and composition are provided for backfilling the annular gap created as a tunnel boring machine advances through the ground. The fill material is comprised of two components that are combined and mixed together just prior to entering the annular gap. The first component is non-cement slurry consisting of a fluidized bed combustion ash such as coal ash. The second component consists of an alkali silicate such as sodium silicate. Additionally, ordinary Portland cement and/or metakaolin can be added to the grout composition.