摘要:
Cementitious compositions and processes for preparing and using the cementitious compositions are provided. The cementitious compositions are characterized by the property of a reduced or an attenuated water vapor emission from a cementitious mix and a concrete formed therefrom.
摘要:
A method for preparing an improved concrete wherein a chemical admix is slurried with water and a pozzolan material prior to its incorporation in the concrete. This method reduces the slump loss of the concrete during transportation, and increases its workability in the form at the point of use without any sacrifice in strength.
摘要:
A lightweight aggregate for use in forming lightweight cementitious mixes and/or concrete is formed by encapsulating a plurality of hydrophobic polymer particles (e.g., expanded polystyrene particles) in an encasement having a first layer of a cementitious material and a second layer of a pozzolan or mineral. The lightweight aggregate can be included as at least part of the aggregate component of a cementitious mix to form a lightweight cementitious mix. The lightweight aggregate and/or lightweight cementitious mix can be used to form lightweight concrete. The encasement of the lightweight aggregate allows the cement of the cementitious mix or concrete composition to bond to the lightweight aggregate, thereby promoting strength and durability of the concrete mixture.
摘要:
Provided are procedures for estimating the amount of water vapor emissions as well as other properties, such as slump and volume yield, of a concrete or cementitious mix used in producing a concrete.
摘要:
A cement composition comprising cement, a pozzolan material, fine aggregate, air, water, at least one alkali metal constituent selected from the group consisting of sodium, potassium, and lithium ions, and at least one anionic constituent which is capable of forming complexes with ferric ions, is soluble in water, and forms a calcium salt which is also water soluble, wherein the alkali metal constituent is present in an amount up to approximately 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material; the anionic constituent is present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material; and the cement composition is further characterized by: (a) having a solid volume ratio of cement to the pozzolan material within the range of approximately 0.05 to 2.0; (b) having a ratio of the volume of paste (fly ash, cement, air, and water) to the solid volume of sand within the range of approximately 0.75 to 2.5; and (c) having a ratio of the solid volume of cement to the volume of mortar less than about 0.19. The cement composition of the present invention is substantially less expensive than cement compositions presently employed in the industry having equivalent compressive strengths.
摘要:
A cementitious composition comprising Portland cement and a finely divided limestone accelerator. The Portland cement has a fineness of at least about 3,200 Blaine. The composition may contain one or more blast furnace slags or pozzolans, such as fly ash or silica fume. When pozzolans or slags are present, the weight ratio of limestone to a mortar mixture of Portland cement, limestone, sand, water, and pozzolans or blast furnace slags, is in the range of about 1.4% to about 5.6%. The finely divided limestone acts as an accelerator, decreasing the initial set time of the resulting composition, and increasing the rate of strength gain.
摘要:
A cement composition comprising cement, a self-setting pozzolan material, fine aggregate, air, water, at least one alkali metal constituent selected from the group consisting of sodium, potassium, and lithium ions, and at least one anionic constituent which is soluble in water and forms a calcium salt which is also water soluble, and a water soluble oxide of boron compound wherein the alkali metal constituent is present in an amount up to approximately 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material, the anionic constituent is present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material; the water soluble oxide of boron compound is present in the range of about 0.01 to 2.0 percent, in terms of the equivalent weight of borate ions (BO.sub.3.sup..ident.), by weight of the pozzolan material; the pozzolan material being self-setting; and the cement composition is further characterized by: (a) having a solid volume ratio of cement to the pozzolan material within the range of approximately 0.05 to 2.0; (b) having a ratio of the volume of paste (pozzolan, cement, air and water) to the solid volume of sand within the range of approximately 0.75 to 2.5; and (c) having a ratio of the solid volume of cement to the volume of mortar less than about 0.19.