A composition of a cement additive material to improve durability of cementitious structures, was disclosed. The cement additive composition includes an admixture of one or more of divalent magnesium metal silicates with capacity to act as a latent hydraulic binder in said composition activated by a hydration process under aqueous conditions, and in particular the divalent metal silicate is magnesium-dominated silicate, preferably comprising mineral groups of olivines, orthopyroxenes, amphiboles, talc and serpentines or mixtures thereof. The composition also includes chloride ions or brine. Applications of the compositions are also disclosed, in particular to utilize a property of hydration as a major trigger for the latent hydraulic reaction of magnesium silicates, particularly for said olivines, when exposed to water and brines, in order to obtain a cementitious material becoming self healing.

A composition of a cement additive material to improve durability of cementitious structures, was disclosed. The cement additive composition includes an admixture of one or more of divalent magnesium metal silicates with capacity to act as a latent hydraulic binder in said composition activated by a hydration process under aqueous conditions, and in particular the divalent metal silicate is magnesium-dominated silicate, preferably comprising mineral groups of olivines, orthopyroxenes, amphiboles, talc and serpentines or mixtures thereof. The composition also includes chloride ions or brine. Applications of the compositions are also disclosed, in particular to utilize a property of hydration as a major trigger for the latent hydraulic reaction of magnesium silicates, particularly for said olivines, when exposed to water and brines, in order to obtain a cementitious material becoming self healing.

A composition of a cement additive material to improve durability of cementitious structures, was disclosed. The cement additive composition includes an admixture of one or more of divalent magnesium metal silicates with capacity to act as a latent hydraulic binder in said composition activated by a hydration process under aqueous conditions, and in particular the divalent metal silicate is magnesium-dominated silicate, preferably comprising mineral groups of olivines, orthopyroxenes, amphiboles, talc and serpentines or mixtures thereof. The composition also includes chloride ions or brine. Applications of the compositions are also disclosed, in particular to utilize a property of hydration as a major trigger for the latent hydraulic reaction of magnesium silicates, particularly for said olivines, when exposed to water and brines, in order to obtain a cementitious material becoming self healing.

A post-treatment process for increasing the hot strength of a formed part (100) made of particulate material and binder is disclosed, wherein the formed part (100) is formed a part manufactured by 3D printing (S72) and after its manufacture is heated (S30) using a heating device (40), and the heated formed part (100) is exposed (S50) to an atmosphere enriched with gaseous water generated by supplying water.

A post-treatment process for increasing the hot strength of a formed part (100) made of particulate material and binder is disclosed, wherein the formed part (100) is formed a part manufactured by 3D printing (S72) and after its manufacture is heated (S30) using a heating device (40), and the heated formed part (100) is exposed (S50) to an atmosphere enriched with gaseous water generated by supplying water.

A cementitious composition includes (i) white Portland cement having a fineness of about 350-550 m.sup.2/kg, D90 between about 11-50 m, and total combined iron oxide, manganese oxide, and chromium oxide <1.0% by weight (ii) light color pozzolan such as white silica fume, and (iii) at least one light color particulate material, such as ground granulated blast furnace slag (GGBFS) having a fineness greater than that of the white Portland cement, a D90 less than that of the white Portland cement, and total combined iron oxide, manganese oxide, and chromium oxide content <3.0% by weight and/or coarse limestone powder having a D90 greater than that of the white cement. The cementitious composition may include one or more of aggregates, fibers, or admixture. The cementitious composition can be a dry blend, fresh cementitious mixture, or hardened cementitious composition. The cementitious composition can be precast concrete, stucco, GFRC, UHPC or SCC.

A cementitious composition includes (i) white Portland cement having a fineness of about 350-550 m.sup.2/kg, D90 between about 11-50 m, and total combined iron oxide, manganese oxide, and chromium oxide <1.0% by weight (ii) light color pozzolan such as white silica fume, and (iii) at least one light color particulate material, such as ground granulated blast furnace slag (GGBFS) having a fineness greater than that of the white Portland cement, a D90 less than that of the white Portland cement, and total combined iron oxide, manganese oxide, and chromium oxide content <3.0% by weight and/or coarse limestone powder having a D90 greater than that of the white cement. The cementitious composition may include one or more of aggregates, fibers, or admixture. The cementitious composition can be a dry blend, fresh cementitious mixture, or hardened cementitious composition. The cementitious composition can be precast concrete, stucco, GFRC, UHPC or SCC.

Described herein are methods of cementing at least a portion of a well comprising feeding a magnetorheological cementitious slurry to a well and applying a magnetic field to the magnetorheological cementitious slurry concurrent with at least a portion of said feeding step to cause a mechanical response in said magnetorheological cementitious slurry in the well. Also disclosed herein are methods of temporarily blocking at least a portion of a well comprising providing a magnetorheological fluid in a well, applying a magnetic field to cause a mechanical response in said magnetorheological fluid thereby blocking at least a portion of the well, and removing the magnetic field to unblock the portion of the well. Also disclosed herein is a magnetorheological cement.

Described herein are methods of cementing at least a portion of a well comprising feeding a magnetorheological cementitious slurry to a well and applying a magnetic field to the magnetorheological cementitious slurry concurrent with at least a portion of said feeding step to cause a mechanical response in said magnetorheological cementitious slurry in the well. Also disclosed herein are methods of temporarily blocking at least a portion of a well comprising providing a magnetorheological fluid in a well, applying a magnetic field to cause a mechanical response in said magnetorheological fluid thereby blocking at least a portion of the well, and removing the magnetic field to unblock the portion of the well. Also disclosed herein is a magnetorheological cement.

A glass furnace including an additive-containing product including an additive selected from: phosphorus compounds other than glasses and vitroceramics, tungsten compounds other than glasses and vitroceramics, molybdenum compounds other than glasses and vitroceramics, iron in the form of metal, aluminum in the form of metal, silicon in the form of metal, and their mixtures, silicon carbide, boron carbide, silicon nitride, boron nitride, glasses including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, vitroceramics including elemental phosphorus and/or iron and/or tungsten and/or molybdenum, and their mixtures, and having the following chemical analysis, exclusively of the additive, as a percentage by weight on the basis of the oxides: Cr.sub.2O.sub.3?2%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+CaO+ZrO.sub.2+MgO+Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2?90%, and Cr.sub.2O.sub.3+Al.sub.2O.sub.3+MgO?60%, the content by weight of additive being in the range 0.01% to 6%.