A multi-zone cementitious product, which includes a base zone made of a first cementitious material composition and forming a portion of the product. At least one facing zone is adjacent to and bonded to the base zone, the facing zone made of a second cementitious material composition and forming at least one exterior face of said product which is visible when the product is installed. A disrupted boundary layer is between the facing zone and the base zone, and includes material from both the facing zone and the base zone. The disrupted boundary layer bonds the facing zone to the base zone. The facing zone has a thickness sufficient to prevent the base zone from being visible when the product is installed.

The invention provides novel methods and compositions that mitigate the occurrence of hazing of products made from carbonatable calcium silicate-based cements. The methods and compositions of the invention may be applied in a variety of cement and concrete components in the infrastructure, construction, pavement and landscaping industries.

A method for preparing Portland cement includes: respectively weighing iron slag, copper slag, vanadium slag, and nickel slag and grinding, to yield prefabricated iron slag, prefabricated copper slag, prefabricated vanadium slag, and prefabricated nickel slag; weighing mica and kaolinite, mixing, and grinding to obtain aluminous raw materials; evenly mixing the prefabricated iron slag and the aluminous raw materials, and calcining, to yield an iron-aluminum eutectic mineral; weighing the marble, fluorite, dolomite, and quartz, evenly mixing the marble, fluorite, dolomite, and quartz with the prefabricated copper slag, prefabricated vanadium slag, and prefabricated nickel slag to yield a first mixture; grinding the iron-aluminum eutectic mineral to yield powders, and calcining a second mixture of the first mixture and the powders, to yield the cement clinker; and cooling the cement clinker, and grinding a third mixture of the cooled cement clinker and the gypsum, to yield the Portland cement.

Disclosed is an electrically conductive cement-based composite composition capable of exhibiting stable electrical performance since carbon nanotubes and carbon fibers are mixed in cement at a proper weight ratio so as to lower sensitivity to a specific resistance change caused by the change in a water/cement ratio (w/c). The electrically conductive cement-based composite composition includes, in order to have stable electrical characteristics of which a specific resistance is 100 .Math.cm or less even with the change in the water/cement ratio (w/c), the cement, 0.1-0.5 wt % of the carbon nanotubes on the basis of the cement weight, 0.1-0.4 wt % of the carbon fibers on the basis of the cement weight, and silica fume and a superplasticizer as other additives.

A method of cementing a wellbore penetrating a subterranean formation comprises blending a base cement slurry with one or more liquid additives to provide a cementing composition, the base cement slurry comprising a liquid carrier, a class G cement or a blend of class G and class C cements as defined by the American Petroleum Institute (API) Specification 10A standards (R2015), and silica fume, or fumed silica, or a combination of silica fume and fumed silica, the base cement slurry having a density of about 14 to about 16 ppg; and injecting the cementing composition into the wellbore. The single base cement slurry can be used globally to make cementing compositions having wide ranges of density and temperature stability.

A method of cementing a wellbore penetrating a subterranean formation comprises blending a base cement slurry with one or more liquid additives to provide a cementing composition, the base cement slurry comprising a liquid carrier, a class G cement or a blend of class G and class C cements as defined by the American Petroleum Institute (API) Specification 10A standards (R2015), and silica fume, or fumed silica, or a combination of silica fume and fumed silica, the base cement slurry having a density of about 14 to about 16 ppg; and injecting the cementing composition into the wellbore. The single base cement slurry can be used globally to make cementing compositions having wide ranges of density and temperature stability.

A method of cementing a wellbore penetrating a subterranean formation comprises blending a base cement slurry with one or more liquid additives to provide a cementing composition, the base cement slurry comprising a liquid carrier, a class G cement or a blend of class G and class C cements as defined by the American Petroleum Institute (API) Specification 10A standards (R2015), and silica fume, or fumed silica, or a combination of silica fume and fumed silica, the base cement slurry having a density of about 14 to about 16 ppg; and injecting the cementing composition into the wellbore. The single base cement slurry can be used globally to make cementing compositions having wide ranges of density and temperature stability.

A method of cementing a wellbore penetrating a subterranean formation comprises blending a base cement slurry with one or more liquid additives to provide a cementing composition, the base cement slurry comprising a liquid carrier, a class G cement or a blend of class G and class C cements as defined by the American Petroleum Institute (API) Specification 10A standards (R2015), and silica fume, or fumed silica, or a combination of silica fume and fumed silica, the base cement slurry having a density of about 14 to about 16 ppg; and injecting the cementing composition into the wellbore. The single base cement slurry can be used globally to make cementing compositions having wide ranges of density and temperature stability.

Cementitious compositions and methods for preparing and using the cementitious compositions to yield hardened concrete. The cementitious compositions yield hardened concrete having reduced or attenuated water vapor emission and lower internal relative humidity (IRH). Cementitious compositions are characterized by the property of rapid surface drying while maintaining good workability, particularly when using porous lightweight aggregates that absorb substantial amounts of water. Methods of decreasing water availability and increasing surface drying of concrete, including lightweight concrete, are provided. A water soluble ionic salt may be used to sequester water within the pores and capillaries of the cement paste and/or porous lightweight aggreate by modifying the colligative propertie of pore water. The salt may be added directly to concrete or the concrete mix water, or, alternatively, aggregates may be infused with a water-salt solution to provide treated porous aggregates having improved water saturation and water retention.

A cementitious composition comprising a crystalline phase and an amorphous phase, and an activator selected from the group of materials comprising inorganic bases. In some cases the crystalline phase is gehlenite. In some cases the crystalline phase is anorthite. In some cases the amorphous phase is amorphous calcium aluminum silicate. In some cases the activator is elected from OPC (1-70 wt %), free lime (1-20 wt %), calcium hydroxide (1-20 wt %), and alkali hydroxides (NaOH, KOH 1 to 10 wt %), individually or in combination. A low lime cementitious material is cured by reaction with a curing reagent that includes a reagent chemical that is synthesized from CO.sub.2. Examples of such a reagent are oxalic acid and tartaric acid.