A cement composition is disclosed that includes a cement slurry and an epoxy resin system that includes at least one epoxy resin and a curing agent. The cement slurry has a density in a range of from 65 pcf to 180 pcf and includes a cement precursor material, silica sand, silica flour, a weighting agent, and manganese tetraoxide. The epoxy resin system includes at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, bisphenol-A-epichlorohydrin epoxy resin, or a compound having formula (I): (OC.sub.2H.sub.3)—CH.sub.2—O—R.sup.1—O—CH.sub.2—(C.sub.2H.sub.3O) where R.sup.1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms; and a curing agent.

A cement composition is disclosed that includes a cement slurry and an epoxy resin system that includes at least one epoxy resin and a curing agent. The cement slurry has a density in a range of from 65 pcf to 180 pcf and includes a cement precursor material, silica sand, silica flour, a weighting agent, and manganese tetraoxide. The epoxy resin system includes at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, bisphenol-A-epichlorohydrin epoxy resin, or a compound having formula (I): (OC.sub.2H.sub.3)—CH.sub.2—O—R.sup.1—O—CH.sub.2—(C.sub.2H.sub.3O) where R.sup.1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms; and a curing agent.

Gypsum panels and methods for their manufacture are provided herein. The gypsum panels include a gypsum core having a first surface and a second opposed surface and a first fiberglass mat associated with the first surface of the gypsum core, such that gypsum from the gypsum core penetrates at least a portion of the first fiberglass mat.

Gypsum panels and methods for their manufacture are provided herein. The gypsum panels include a gypsum core having a first surface and a second opposed surface and a first fiberglass mat associated with the first surface of the gypsum core, such that gypsum from the gypsum core penetrates at least a portion of the first fiberglass mat.

A method of designing a cement slurry may include: (a) selecting at least a cement and concentration thereof, water and concentration thereof, and, optionally, at least one supplementary cementitious material and a concentration thereof, such that a cement slurry comprising the cement, the water, and, if present, the at least one supplementary cementitious material, meet a density requirement; (b) calculating a thickening time of the cement slurry using a thickening time model; (c) comparing the thickening time of the cement slurry to a thickening time requirement, wherein steps (a)-(c) are repeated if the thickening time of the cement slurry does not meet or exceed the thickening time requirement, wherein the selecting comprises selecting different concentrations and/or different chemical identities for the cement and/or the supplementary cementitious material than previously selected, or step (d) is performed if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and preparing the cement slurry.

A method of designing a cement slurry may include: (a) selecting at least a cement and concentration thereof, water and concentration thereof, and, optionally, at least one supplementary cementitious material and a concentration thereof, such that a cement slurry comprising the cement, the water, and, if present, the at least one supplementary cementitious material, meet a density requirement; (b) calculating a thickening time of the cement slurry using a thickening time model; (c) comparing the thickening time of the cement slurry to a thickening time requirement, wherein steps (a)-(c) are repeated if the thickening time of the cement slurry does not meet or exceed the thickening time requirement, wherein the selecting comprises selecting different concentrations and/or different chemical identities for the cement and/or the supplementary cementitious material than previously selected, or step (d) is performed if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and preparing the cement slurry.

A method for preparing a graphene-nanosheets based concrete additive is disclosed. The method comprises mixing Polycarboxylate ether A (PCE-A) to a retarder - based salt solution to obtain a retarder-based Polycarboxylate ether A solution. In the next step, a retarder based PCE solution is obtained by adding Polycarboxylate ether B to the retarder based Polycarboxylate ether A solution to which graphene nanosheets are added. Further, an air entrainment agent is added to graphene nanosheets based PCE solution and further mixed to obtain the graphene nanosheets based concrete additive.

A delivery device for concrete admixtures, in the form of a film of watersoluble material, having a concrete admixture incorporated within the film. The film can be attached to a formwork for concrete and has a protective layer, which is removable to allow the water in the concrete to dissolve the film and release the admixture into the concrete. The film contains the required quantity of admixture and is weather-resistant and substantially time-insensitive. The delivery device is used in a process to retard the setting portion of a surface of concrete.

A delivery device for concrete admixtures, in the form of a film of watersoluble material, having a concrete admixture incorporated within the film. The film can be attached to a formwork for concrete and has a protective layer, which is removable to allow the water in the concrete to dissolve the film and release the admixture into the concrete. The film contains the required quantity of admixture and is weather-resistant and substantially time-insensitive. The delivery device is used in a process to retard the setting portion of a surface of concrete.

The invention provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.