Hydrophobic aggregates for use in refractory castables and gunning mixtures and methods of their preparation. The aggregates here are formed by crushing insulating fire brick and coating the resulting particles with a hydrophobic component. The hydrophobic component may be a polydimethylsiloxane having a terminal silanol group. As a result of the coating process, the coated aggregate has very low levels of alkalis. The aggregates may be used to form refractory castables that do not undergo substantial alkaline hydrolysis due to the reduced levels of alkalis. The castables made from these aggregates display superior physical properties, including lower water content, lower permanent linear change, high strength, and superior thermal conductivity/insulation properties, while at the same time possessing lower density and requiring less water to be used during castable formation. These improved properties also are observed in gunning mixtures formed from these aggregates.

Methods and compositions are provided that utilize high-alumina refractory aluminosilicate pozzolans in well cementing. An embodiment discloses a method of cementing comprising: introducing a cement composition into a subterranean formation, wherein the cement composition comprises: a component selected from the group consisting of cement kiln dust, Portland cement, and any combination thereof; a high-alumina refractory aluminosilicate pozzolan; and water; and allowing the cement composition to set.

Methods and compositions are provided that utilize high-alumina refractory aluminosilicate pozzolans in well cementing. An embodiment discloses a method of cementing comprising: introducing a cement composition into a subterranean formation, wherein the cement composition comprises: a component selected from the group consisting of cement kiln dust, Portland cement, and any combination thereof; a high-alumina refractory aluminosilicate pozzolan; and water; and allowing the cement composition to set.

Hydrophobic aggregates for use in refractory castables and gunning mixtures and methods of their preparation. The aggregates here are formed by crushing insulating fire brick and coating the resulting particles with a hydrophobic component. The hydrophobic component may be a polydimethylsiloxane having a terminal silanol group. As a result of the coating process, the coated aggregate has very low levels of alkalis. The aggregates may be used to form refractory castables that do not undergo substantial alkaline hydrolysis due to the reduced levels of alkalis. The castables made from these aggregates display superior physical properties, including lower water content, lower permanent linear change, high strength, and superior thermal conductivity/insulation properties, while at the same time possessing lower density and requiring less water to be used during castable formation. These improved properties also are observed in gunning mixtures formed from these aggregates.

Hydrophobic aggregates for use in refractory castables and gunning mixtures and methods of their preparation. The aggregates here are formed by crushing insulating fire brick and coating the resulting particles with a hydrophobic component. The hydrophobic component may be a polydimethylsiloxane having a terminal silanol group. As a result of the coating process, the coated aggregate has very low levels of alkalis. The aggregates may be used to form refractory castables that do not undergo substantial alkaline hydrolysis due to the reduced levels of alkalis. The castables made from these aggregates display superior physical properties, including lower water content, lower permanent linear change, high strength, and superior thermal conductivity/insulation properties, while at the same time possessing lower density and requiring less water to be used during castable formation. These improved properties also are observed in gunning mixtures formed from these aggregates.

An alkaline-activated binder system for fire concretes includes at least one mineral binder and a mineral activator which, in a mixture with water, form a curing geopolymer, where a combination of at least two magnesium components (Mg components) which give an alkaline reaction with water and react with the binder at different times to form a geopolymer is present as activator, where the magnesium components have a different reactivity in respect of atmospheric moisture and/or in respect of the binder. A dry fire concrete mix contains the binder system and the mix may be used in, for example, facilities in the steel industry.

An alkaline-activated binder system for fire concretes includes at least one mineral binder and a mineral activator which, in a mixture with water, form a curing geopolymer, where a combination of at least two magnesium components (Mg components) which give an alkaline reaction with water and react with the binder at different times to form a geopolymer is present as activator, where the magnesium components have a different reactivity in respect of atmospheric moisture and/or in respect of the binder. A dry fire concrete mix contains the binder system and the mix may be used in, for example, facilities in the steel industry.

The invention relates to the use of feldspar granules with a particular combination of oxide constituents in the manufacture of artificial agglomerate stone materials and to the agglomerate stone materials resulting thereof.

The invention relates to the use of feldspar granules with a particular combination of oxide constituents in the manufacture of artificial agglomerate stone materials and to the agglomerate stone materials resulting thereof.

An insulating monolithic refractory material having sufficient curing strength and usable time ensured and exhibiting excellent stability at high temperature. The insulating monolithic refractory material comprises a binder and a refractory raw material; a bulk specific gravity thereof is 0.8 to 1.8 when a kneaded mixture of the insulating monolithic refractory material with water is cured at normal temperature for 24 hours and then dried at 110 C. for 24 hours; the binder comprises a calcium aluminate cement including CaO and Al.sub.2O.sub.3 as chemical components and a strontium aluminate cement including SrO and Al.sub.2O.sub.3 as chemical components; and on the basis of 100% by mass as a total mass of the binder and the refractory raw material, a content of the strontium aluminate cement is 2 to 10% by mass, and a content of CaO derived from the calcium aluminate cement is 1 to 12% by mass.