Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B14/02—Granular materials, e.g. microballoons
  • C04B14/04—Silica-rich materials; Silicates
  • C04B14/10—Clay
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators or shrinkage compensating agents
  • C04B22/08—Acids or salts thereof
  • C04B22/10—Acids or salts thereof containing carbon in the anion, e.g. carbonates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators or shrinkage compensating agents
  • C04B22/08—Acids or salts thereof
  • C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B7/00—Hydraulic cements
  • C04B7/36—Manufacture of hydraulic cements in general
  • C04B7/48—Clinker treatment
  • C04B7/52—Grinding ; After-treatment of ground cement

Definitions

• This disclosure relates to a cement composition and a method for producing the same.
• cement compositions are being used in which part of the cement clinker, which emits a large amount of CO2 during production, is replaced with admixtures.
• Limestone is widely used as an admixture added to cement because it is easy to obtain and inexpensive.
• Non-Patent Document 1 the amount of admixtures added to ordinary Portland cement is set at 5% by mass or less according to JIS R 5210:2009.
• JIS R 5210:2009 the amount of admixtures added to ordinary Portland cement is set at 5% by mass or less according to JIS R 5210:2009.
• simply adding more limestone than the current 5% by mass results in a decrease in strength compared to ordinary Portland cement (for example, Non-Patent Document 1).
• Non-Patent Document 2 Japanese Patent Document 2
• Non-Patent Document 2 the kaolin that is the raw material for metakaolin mentioned in Non-Patent Document 2 is produced in limited regions and countries. Therefore, if there is a material other than kaolin that can be used as an admixture, it would be extremely useful in developing low-carbon cement.
• the present disclosure has been made in consideration of the above circumstances, and aims to provide a low-carbon cement composition with excellent strength development and a method for producing the same.
• One aspect of the present disclosure is a cement composition
• a cement composition comprising cement clinker, inorganic minerals, carbonates, and gypsum
• the inorganic mineral has a BET specific surface area that is reduced by pulverization,
• the content of the inorganic mineral is 0.5 to 14.0 mass %
• the cement composition has a total content of the inorganic mineral and the carbonate in a range from 5% by mass to 15% by mass or less, and a total content of the cement clinker and the gypsum in a range from 85% by mass to less than 95% by mass.
• the cement composition contains inorganic minerals whose BET specific surface area is reduced by grinding. Such inorganic minerals have fine pores before grinding, and have a large BET specific surface area because they adsorb nitrogen into the pores. When such inorganic minerals are ground, the microstructure forming the pores is destroyed, so the BET specific surface area is reduced. When such a microstructure is destroyed, the hydration reaction of the cement is facilitated, which contributes to the strength development of the cement composition.
• the cement composition contains a predetermined amount of such inorganic minerals and carbonates along with cement clinker and gypsum. Therefore, the cement composition has excellent strength development despite being low carbon type.
• the low carbon type cement composition means a cement composition that can reduce CO2 emissions when producing the cement composition by replacing cement clinker with an admixture.
• One aspect of the present disclosure includes a mixing step of mixing an inorganic mineral, a cement clinker, a carbonate, and gypsum, the BET specific surface area of which is reduced by pulverization, to obtain a cement composition having a content of the inorganic mineral of 0.5 to 14.0 mass%, a total content of the inorganic mineral and the carbonate of more than 5 mass% and 15 mass% or less, and a total content of the cement clinker and the gypsum of 85 mass% or more and less than 95 mass%,
• the present invention provides a method for producing a cement composition, wherein in the mixing step, the cement composition is mixed while being pulverized so that the Blaine specific surface area of the cement composition becomes 3000 cm 2 /g or more.
• the method for producing the cement composition includes a mixing step of mixing inorganic minerals, carbonates, cement clinker, and gypsum, the BET specific surface area of which is reduced by grinding, to obtain a cement composition containing these in a predetermined ratio.
• the inorganic minerals are ground, the microstructure that forms the pores is destroyed, so that the BET specific surface area is reduced.
• the hydration reaction of the cement is easily promoted, which contributes to the strength development of the cement composition.
• the inorganic minerals are mixed while being ground in the mixing step so that the Blaine specific surface area of the cement composition is 3000 cm 2 /g or more, so that the inorganic minerals are moderately ground to promote the hydration reaction of the cement. This makes it possible to obtain a cement composition that is low carbon but has excellent strength development.
• One aspect of the present disclosure is a first grinding step of grinding an inorganic mineral to obtain a pulverized material having a lower BET specific surface area than the inorganic mineral;
• the present invention provides a method for producing a cement composition, which has an inorganic mineral content of 0.5 to 14.0 mass%, a total content of the inorganic mineral and the carbonate of more than 5 mass% and less than 15 mass%, and a total content of the cement clinker and the gypsum of 85 mass% or more and less than 95 mass%, and has a Blaine specific surface area of 3,000 cm2 /g or more.
• the method for producing the cement composition described above involves pulverizing inorganic minerals in a first crushing step to obtain a pulverized product having a lower BET specific surface area than the inorganic minerals before crushing. Such pulverized products are obtained by destroying the microstructure that forms the pores of the inorganic minerals, so the hydration reaction of the cement is more likely to proceed, which contributes to the strength development of the cement composition.
• a cement composition is obtained in which the inorganic mineral content, the total content of the inorganic minerals and carbonates, and the total content of the cement clinker and gypsum are in a predetermined ratio. In this way, a cement composition that is low carbon yet has excellent strength development properties can be obtained.
• the present disclosure can provide a low-carbon cement composition with excellent strength development and a method for producing the same.
• the exemplified materials can be used alone or in combination of two or more types.
• the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.
• a cement composition according to one embodiment includes inorganic minerals, carbonates, cement clinker, and gypsum. By including inorganic minerals in the cement composition, the cement clinker content can be reduced. This allows the cement composition to be a low-carbon cement composition that can reduce CO2 emissions during production.
• the Blaine specific surface area of the cement composition is 3000 cm 2 /g or more, preferably 3150 cm 2 /g or more, more preferably 3300 cm 2 /g or more, even more preferably 3500 cm 2 /g or more, and particularly preferably 3700 cm 2 /g or more.
• the Blaine specific surface area of the cement composition is preferably 6000 cm 2 /g or less, more preferably 5000 cm 2 /g or less, and even more preferably 4600 cm 2 /g or less.
• the cement clinker may be Portland cement clinker used to prepare various Portland cements as specified in JIS R 5210:2009 "Portland cement”.
• Examples of Portland cement clinker include ordinary Portland cement clinker, high-early strength Portland cement clinker, moderate-heat Portland cement clinker, low-heat Portland cement clinker, oil well Portland cement clinker, etc.
• the Portland cement clinker may include at least one selected from the group consisting of ordinary Portland cement clinker and high-early strength Portland cement clinker, and preferably includes ordinary Portland cement clinker.
• Cement clinker contains C3S , C2S , C3A , and C4AF as mineral compositions.
• the contents of C3S , C2S , C3A , and C4AF can be calculated by the Bogue formula.
• the Bogue formula is a widely used formula for calculating the contents of major minerals in cement clinker from the content ratios of their chemical compositions.
• the amount of C 3 S in the cement clinker is preferably 30.0 to 70.0 mass%, more preferably 40.0 to 66.0 mass%, and even more preferably 50.0 to 65.0 mass%.
• the amount of C 2 S in the cement clinker is preferably 5.0 to 65.0 mass%, more preferably 8.0 to 50.0 mass%, even more preferably 10.0 to 40.0 mass%, even more preferably 12.0 to 30.0 mass%, and particularly preferably 12.0 to 25.0 mass%.
• the amount of C3A in the cement clinker is preferably 7.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 8.5% by mass or more, even more preferably 9.0% by mass or more, and particularly preferably 9.5% by mass or more.
• the amount of C3A in the cement clinker is preferably 13.0% by mass or less, more preferably 12.0% by mass or less, even more preferably 11.0% by mass or less, and even more preferably 10.5% by mass or less.
• the amount of C3A within the above range, the regeneration of ettringite (a compound represented by 3CaO.Al2O3.3CaSO4.32H2O ) can be suppressed, and the increase in adiabatic temperature rise during hardening of the cement composition can be suppressed.
• the amount of C4AF in the cement clinker is preferably 7.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 9.0% by mass or more, even more preferably 9.5% by mass or more, and particularly preferably 9.8% by mass or more.
• the amount of C4AF in the cement clinker is preferably 14.0% by mass or less, more preferably 13.0% by mass or less, even more preferably 12.0% by mass or less, even more preferably 11.0% by mass or less, and particularly preferably 10.4% by mass or less.
• the content of cement clinker based on the total amount of the cement composition may be, for example, 80 to 93 mass%, 83 to 92 mass%, or 85 to 91 mass%.
• the content of Portland cement clinker in the cement composition is 80 mass% or more, 83 mass% or more, or 85 mass% or more, better compressive strength can be obtained.
• the content of Portland cement clinker in the cement composition is 93 mass% or less, 92 mass% or less, or 91 mass% or less, CO2 emissions can be further reduced.
• the inorganic mineral may be a mineral produced by weathering a volcanic ejecta, i.e., a mineral derived from a volcanic ejecta.
• the volcanic ejecta include volcanic ash, volcanic lapilli, pumice, pyroclastic flow deposits, and the like.
• the inorganic mineral may be a mineral produced by weathering an igneous rock. Examples of the igneous rock include granite, and the like. Allophane is produced by weathering a volcanic ejecta or an igneous rock, and halloysite is produced by further weathering of allophane, and kaolin is produced by further weathering of halloysite. Kaolin, allophane, and halloysite are clay minerals.
• inorganic minerals examples include allophane, halloysite, imogolite, illite, montmorillonite, and pyrophyllite.
• the SiO 2 /Al 2 O 3 mass ratio of these inorganic minerals may be 0.5 to 3.0.
• the inorganic mineral preferably contains allophane or halloysite, and more preferably contains allophane.
• Allophane is an amorphous inorganic mineral.
• examples of inorganic minerals containing allophane include Kanuma soil and Sekado P1 (product name, manufactured by Shinagawa General Co., Ltd.).
• the term "inorganic mineral” includes various forms such as aggregates and granules, pulverized materials obtained by pulverizing aggregates or particles, aggregates of particles, and granulated materials.
• the BET specific surface area of such inorganic minerals is preferably 30 to 350 m 2 /g.
• the BET specific surface area of the inorganic mineral is preferably 350 m 2 /g or less, more preferably 300 m 2 /g or less, even more preferably 270 m 2 /g or less, even more preferably 200 m 2 /g or less, and particularly preferably 180 m 2 /g or less.
• the BET specific surface area of the inorganic mineral is preferably 50 m 2 /g or more, more preferably 70 m 2 /g or more, even more preferably 100 m 2 /g or more, and still more preferably 150 m 2 /g or more.
• the BET specific surface area is a value obtained from a BET plot in the relative pressure range of 0.05 to 0.35 by the BET multipoint method using nitrogen gas.
• the Blaine specific surface area of the inorganic mineral can be measured in accordance with the description of JIS R 5201:2015 "Physical measurement method of cement".
• the Blaine specific surface area of the inorganic mineral is, for example, 8000 cm 2 /g or more, preferably 10000 cm 2 /g or more, more preferably 12000 cm 2 /g or more, even more preferably 14000 cm 2 /g or more, and even more preferably 18000 cm 2 /g or more. This can further increase the strength expression of the cement composition.
• the Blaine specific surface area of the inorganic mineral is, for example, 30000 cm 2 /g or less, preferably 28000 cm 2 /g or less, and more preferably 26000 cm 2 /g or less. This can reduce the crushing cost.
• the inorganic mineral is one whose BET specific surface area is reduced by pulverization.
• the inorganic mineral may be one whose Blaine specific surface area is increased by pulverization.
• the microstructure such as the layer structure of SiO2 and Al2O3 constituting the pores , is destroyed by pulverization.
• the coordination number of Al atoms changes from six to four, and the bonding state of atoms also changes. It is believed that such changes in the microstructure and molecular structure facilitate the progress of the hydration reaction of cement, improving the strength development of the cement composition.
• the pulverized inorganic mineral may be a pulverized product obtained by pulverizing particles or granulated material with a pulverizer such as a mill, or may be a pulverized product obtained by pulverizing the inorganic mineral when preparing the cement composition.
• a cement composition with excellent strength development can be obtained.
• the BET specific surface area of the pulverized inorganic mineral is preferably 180 m 2 /g or less. From the viewpoint of improving the strength development of the cement composition, the BET specific surface area of the pulverized inorganic mineral is more preferably 160 m 2 /g or less, further preferably 100 m 2 /g or less, and even more preferably 80 m 2 /g or less. From the viewpoint of reducing the time required for pulverization, the BET specific surface area of the pulverized inorganic mineral is preferably 3 m 2 /g or more, more preferably 30 m 2 /g or more, further preferably 50 m 2 /g or more, and even more preferably 70 m 2 /g or more.
• the ratio ⁇ of the BET specific surface area of the pulverized inorganic mineral to the BET specific surface area of the inorganic mineral before pulverization is preferably 0.10 to 0.80.
• the ratio ⁇ is preferably 0.20 or more, and more preferably 0.30 or more. This makes it possible to reduce the pulverization cost and the time required for pulverization.
• the ratio ⁇ is preferably 0.70 or less, and more preferably 0.60 or less. This makes it possible to further increase the strength development of the cement composition.
• the ratio ⁇ of the Blaine specific surface area of the crushed material to the Blaine specific surface area of the inorganic mineral before crushing is preferably 1.10 to 1.50.
• the ratio ⁇ is preferably 1.15 or more, and more preferably 1.20 or more. This allows the strength expression of the cement composition to be further improved.
• the ratio ⁇ is preferably 1.40 or less, and more preferably 1.30 or less. This allows the crushing cost and time required for crushing to be reduced.
• the Blaine specific surface area of the pulverized inorganic mineral is preferably 10,000 cm2 /g or more, more preferably 12,000 cm2 /g or more, even more preferably 14,000 cm2 /g or more, and particularly preferably 18,000 cm2 /g or more. It is preferable that the Blaine specific surface area of the inorganic mineral is increased by 3,000 cm2 /g or more by pulverization. By including such a pulverized material, the compressive strength of the hardened body can be sufficiently increased.
• the insoluble residue of inorganic minerals measured by the method for quantifying insoluble residue using the hydrochloric acid-sodium carbonate method of JIS R 5202:2010 is preferably 1 to 50 mass% or less, more preferably 5 to 40 mass% or less, and particularly preferably 10 to 33 mass% or less.
• inorganic minerals may contain an insoluble residue of 1 mass% or more.
• the SiO2 content of the inorganic mineral is preferably 15 to 55 mass%, more preferably 20 to 45 mass%, and even more preferably 25 to 35 mass%, from the viewpoint of reactivity with Portland cement clinker.
• the Al2O3 content of the inorganic mineral is preferably 15 to 55 mass%, more preferably 20 to 45 mass%, and even more preferably 30 to 40 mass%, from the viewpoint of reactivity with Portland cement clinker.
• the content of the inorganic mineral based on the total amount of the cement composition may be, for example, 0.5 to 14 mass%.
• the content of the inorganic mineral is preferably 1.0 mass% or more, more preferably 1.5 mass% or more, and even more preferably 2.0 mass% or more. This reduces the content of cement clinker in the cement composition, and further reduces CO2 emissions.
• the content of the inorganic mineral is preferably 10.0 mass% or less, more preferably 8.0 mass% or less, even more preferably 5.0 mass% or less, and particularly preferably 4.0 mass% or less. This allows the compressive strength of the hardened body at an age of 28 days to be sufficiently high, and also allows good kneadability to be obtained.
• Carbonates can promote the hydration reaction between Portland cement clinker and inorganic minerals.
• Examples of carbonates include alkali metal carbonates, alkaline earth metal carbonates, and hydrates thereof, such as sodium carbonate, sodium carbonate decahydrate (Na 2 CO 3.10H 2 O), potassium carbonate (K 2 CO 3 ), calcium carbonate (limestone), and magnesium carbonate.
• Sodium sesquicarbonate dihydrate Na 3 H(CO 3 ) 2.NaHCO 3.2H 2 O
• the limestone for example, powders whose main component is calcium carbonate, such as limestone powder and kansui stone powder, which are generally available on the market, can be used.
• the limestone preferably includes limestone that conforms to the minor mixing components described in JIS R 5210:2009 "Portland cement”.
• the carbonate content based on the total amount of the cement composition is preferably 1.0 mass% or more, more preferably 2.0 mass% or more, even more preferably 4.0 mass% or more, and even more preferably 5.0 mass% or more, from the viewpoint of improving fluidity.
• the carbonate content in the cement composition is preferably 14.5 mass% or less, more preferably 14.0 mass% or less, even more preferably 13.0 mass% or less, particularly preferably 11.5 mass% or less, and even more preferably 9.5 mass% or less, from the viewpoint of sufficiently increasing the compressive strength of the hardened body.
• the total content of carbonate and inorganic mineral based on the total amount of the cement composition is more than 5 mass% and 15 mass% or less from the viewpoint of reducing CO2 emissions and increasing strength development. From the viewpoint of further reducing CO2 emissions, the total content of carbonate and inorganic mineral is preferably 6 mass% or more, more preferably 7 mass% or more, and even more preferably 8 mass% or more. From the viewpoint of further increasing the strength development of the cement composition, the total content of carbonate and inorganic mineral is preferably 13 mass% or less, more preferably 12 mass% or less, and even more preferably 10 mass% or less.
• gypsum examples include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum.
• the gypsum may contain one of gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum alone, or may contain a combination of two or more. By containing gypsum in the cement composition, the hydration reaction rate can be adjusted.
• the gypsum content based on the total amount of the cement composition is preferably 0.5 to 3.5 mass%, more preferably 0.7 to 3.0 mass%, and even more preferably 0.8 to 2.5 mass%, calculated as SO3 , with the total amount of the cement composition being 100 mass%.
• the total content of gypsum and cement clinker based on the total amount of the cement composition is 85% by mass or more and less than 95% by mass from the viewpoint of reducing CO2 emissions and increasing strength development.
• the total content of gypsum and cement clinker is preferably 94% by mass or less, more preferably 93% by mass or less, and even more preferably 92% by mass or less.
• the total content of gypsum and cement clinker is preferably 86% by mass or more, more preferably 87% by mass or more, and even more preferably 88% by mass or more.
• the cement composition may contain other components such as inorganic fine powder, calcium hydroxide, powder containing calcium other than calcium hydroxide, water reducing agent for concrete, accelerator, retarder, etc. (however, gypsum, carbonate, and inorganic minerals are excluded).
• inorganic fine powder When the cement composition contains inorganic fine powder, the compressive strength is further improved.
• the content of other components can be 10% by mass or less, 8% by mass or less, or 6% by mass or less based on the total amount of the cement composition.
• inorganic fine powder include powdery materials such as silica stone and crushed stone.
• the content of inorganic fine powder in the cement composition may be more than 0% by mass or 5% by mass or more based on the total amount of the cement composition from the viewpoint of fluidity, and may be 10% by mass or less, 8% by mass or less, or 6% by mass or less from the viewpoint of compressive strength.
• the hardened body may be a hardened paste containing the above-mentioned cement composition and water, or may be a mortar or concrete hardened by mixing water and aggregate.
• the hardening conditions are not particularly limited.
• the hardened body can be prepared in accordance with the method described in JIS R 5201:2015 "Physical test method for cement".
• the amount of water in the paste is preferably 15 parts by mass or more per 100 parts by mass of the total amount of the cement composition from the viewpoint of fluidity, and is preferably 80 parts by mass or less from the viewpoint of making it easier to make the pore structure of the hardened body dense. From these viewpoints, the amount of water is preferably 25 to 80 parts by mass, and more preferably 35 to 60 parts by mass.
• a method for producing a cement composition includes a first grinding step of grinding an inorganic mineral having a BET specific surface area of 30 to 350 m2 /g to obtain a ground product having a lower BET specific surface area than the inorganic mineral, a second grinding step of grinding at least one of cement clinker, gypsum, and carbonate, and a mixing step of mixing at least the ground products obtained in the first grinding step and the second grinding step, thereby obtaining a cement composition having an inorganic mineral content of 0.5 to 14.0 mass%, a total inorganic mineral and carbonate content of more than 5 mass% and 15 mass% or less, and a total cement clinker and gypsum content of 85 mass% or more and less than 95 mass%.
• the inorganic mineral is crushed.
• the BET specific surface area of the inorganic mineral before crushing is preferably 160 m 2 /g or more, more preferably 170 m 2 /g or more, and even more preferably 180 m 2 /g or more. By performing such crushing, the strength development of the cement composition can be sufficiently increased.
• the BET specific surface area of the inorganic mineral before crushing is 350 m 2 /g or less, more preferably 300 m 2 /g or less, and even more preferably 270 m 2 /g or less. This makes it possible to reduce the time and cost required for crushing.
• the ratio ⁇ of the BET specific surface area of the ground product to the BET specific surface area of the inorganic mineral before grinding is 0.10 to 0.80.
• the ratio ⁇ is preferably 0.20 or more, and more preferably 0.30 or more. This makes it possible to reduce the grinding cost and the time required for grinding.
• the ratio ⁇ is preferably 0.70 or less, and more preferably 0.60 or less. This makes it possible to further increase the strength expression of the cement composition.
• the ratio ⁇ of the Blaine specific surface area of the crushed material to the Blaine specific surface area of the inorganic mineral before crushing is preferably 1.10 to 1.50.
• the ratio ⁇ is preferably 1.15 or more, and more preferably 1.20 or more. This can further increase the strength expression of the cement composition.
• the ratio ⁇ is preferably 1.40 or less, and more preferably 1.30 or less. This can reduce the time required for crushing and the crushing costs.
• the grinding may be carried out using a grinding machine.
• grinding machines include a standard mill, a ball mill, a vertical roller mill, and a roller press.
• raw materials other than inorganic minerals i.e., at least one of carbonates, cement clinker, and gypsum
• each of carbonates, cement clinker, and gypsum may be crushed individually, or at least two of these may be crushed together. All of carbonates, cement clinker, and gypsum may be crushed together, or at least one of carbonates, cement clinker, and gypsum may not be crushed. In this way, in the second crushing step, a crushed product containing at least one of carbonates, cement clinker, and gypsum is obtained.
• the mixing step at least the pulverized products obtained in the first and second pulverization steps are mixed together to obtain a cement composition having a Blaine specific surface area of 3000 cm 2 /g or more.
• those not pulverized in the second pulverization step may be directly mixed with the pulverized products in the mixing step.
• the mixing step may be performed using a mixer such as a pan mixer, a tilting mixer, or a ribbon mixer, as well as a pulverizer such as a ball mill, a vertical roller mill, or a roller press.
• a mixer such as a pan mixer, a tilting mixer, or a ribbon mixer
• a pulverizer such as a ball mill, a vertical roller mill, or a roller press.
• One of these may be used alone to perform pulverization or mixing, or a combination of a plurality of them may be used to perform pulverization and mixing.
• the Blaine specific surface area of the cement composition is preferably 5000 cm2 /g or less, more preferably 4500 cm2 /g or less, and even more preferably 4000 cm2 /g or less.
• the Blaine specific surface area of the cement composition is within the above range, it is possible to sufficiently reduce the crushing cost and CO2 emissions while simultaneously achieving a sufficiently high level of strength development and heat suppression.
• the method for producing a cement composition may include any other process in addition to the first crushing process, the second crushing process, and the mixing process.
• a sorting process may be included before or after the crushing process.
• impurities such as sand and iron scraps, which have a large insoluble residue and low reactivity, are removed by sieving, gravity sorting, air classification, magnetic separation, or other methods to adjust the particle size and composition of the inorganic minerals.
• the inorganic minerals so that the insoluble residue of the inorganic minerals, as measured by the method for quantifying the insoluble residue using the hydrochloric acid-sodium carbonate method of JIS R 5202:2010, is 50 mass% or less.
• a method for producing a cement composition according to another embodiment includes a mixing step of mixing inorganic minerals having a BET specific surface area of 30 to 350 m 2 /g and whose BET specific surface area is reduced by grinding, cement clinker, carbonates, and gypsum to obtain a cement composition having an inorganic mineral content of 0.5 to 14.0 mass%, a total inorganic mineral and carbonate content of more than 5 mass% and not more than 15 mass%, and a total cement clinker and gypsum content of 85 mass% or more and less than 95 mass%, and in the mixing step, the materials are mixed while being ground so that the Blaine specific surface area of the cement composition is 3000 cm 2 /g or more, more preferably 4000 cm 2 /g or more.
• the Blaine specific surface area of the cement composition is increased to 3000 cm 2 /g or more, preferably 4000 cm 2 /g or more in the mixing step, a cement composition having excellent strength development can be obtained without using crushed inorganic minerals.
• the Blaine specific surface area of the cement composition is preferably 6000 cm 2 / g or less, more preferably 5000 cm 2 /g or less, and even more preferably 4600 cm 2 /g or less.
• the order of mixing and grinding is not particularly limited. That is, the raw materials may be mixed and then ground, or the raw materials may be ground individually and then mixed, or the raw materials may be mixed and ground simultaneously. Some of the raw materials may be mixed while being ground, and then the other raw materials may be separately ground and/or mixed.
• the mixing step may be performed using, for example, a mixer such as a pan mixer, a tilting mixer, or a ribbon mixer, or a grinder such as a ball mill, a vertical roller mill, or a roller press. One of these may be used alone, or a combination of two or more may be used and mixed while being ground.
• a grinding step for grinding the inorganic mineral may or may not be included.
• the time and cost required for the grinding step can be reduced.
• the BET specific surface area of the inorganic mineral used in the mixing step is preferably 160 m 2 /g or more, more preferably 180 m 2 /g or more, and even more preferably 190 m 2 /g or more.
• the BET specific surface area of the inorganic mineral used is preferably 350 m 2 /g or less, more preferably 300 m 2 /g or less, even more preferably 280 m 2 /g or less, and even more preferably 200 m 2 /g or less.
• the inorganic mineral (ground product) when performing the grinding step, it is preferable to grind the inorganic mineral (ground product) after grinding so that the ratio ⁇ of the BET specific surface area of the inorganic mineral before grinding is 0.10 to 0.80.
• the ratio ⁇ is preferably 0.20 or more, more preferably 0.30 or more. This can reduce the grinding cost and the time required for grinding.
• the ratio ⁇ is preferably 0.70 or less, more preferably 0.60 or less. This can further increase the strength development of the cement composition.
• the inorganic mineral is crushed simultaneously with the other raw materials.
• the preferred range of the ratio ⁇ is as described above.
• the BET specific surface area of the inorganic mineral contained in the cement composition after crushing is determined from the BET specific surface area of the cement composition after crushing. That is, while the BET specific surface area of a cement composition having a Blaine specific surface area of 3,000 to 5,000 cm 2 /g is usually about 1 m 2 /g, the BET specific surface area of the cement composition can be sufficiently increased by containing an inorganic mineral having a large BET specific surface area.
• the BET specific surface area of the cement composition increases by about 3 m 2 /g.
• the BET specific surface area of the entire cement composition decreases due to crushing, so that the cement composition is further crushed, the BET specific surface area is measured, and the ratio of the BET specific surface areas of the inorganic minerals before and after crushing can be obtained by extrapolation.
• the content of the inorganic mineral such as allophane can be determined by an appropriate combination of the XRD Rietveld method, chemical analysis using fluorescent X-rays, wet analysis, gravity separation, SEM-EDS, and TEM-EDS.
• a cement composition comprising cement clinker, inorganic minerals, carbonates, and gypsum
• the inorganic mineral has a BET specific surface area that is reduced by pulverization,
• the content of the inorganic mineral is 0.5 to 14.0 mass %
• the cement composition wherein the total content of the inorganic mineral and the carbonate is more than 5% by mass and less than 15% by mass, and the total content of the cement clinker and the gypsum is 85% by mass or more and less than 95% by mass.
• the inorganic mineral is a pulverized material having a BET specific surface area of 180 m 2 /g or less; a ratio of a BET specific surface area of the pulverized material to a BET specific surface area of the inorganic mineral before pulverization is 0.10 to 0.80;
• the inorganic mineral has a BET specific surface area of 30 to 350 m 2 /g;
• the cement composition according to [1] or [2], wherein the Blaine specific surface area of the cement composition is 4000 cm 2 /g or more.
• the method for producing a cement composition wherein in the mixing step, the cement composition is mixed while being pulverized so that the Blaine specific surface area of the cement composition is 3000 cm 2 /g or more.
• the inorganic mineral is crushed so that the ratio of the BET specific surface area of the inorganic mixture after crushing to the BET specific surface area before crushing is 0.10 to 0.80.
• the method for producing a cement composition according to [7]. further comprises a grinding step of grinding the inorganic mineral to obtain a ground product having a BET specific surface area of 180 m 2 /g or less, which is lower than that of the inorganic mineral;
• the method for producing a cement composition according to [7] wherein in the grinding step, grinding is performed so that the ratio of the BET specific surface area of the ground product to the BET specific surface area of the inorganic mineral before grinding is 0.10 to 0.80.
• the method for producing a cement composition provides a cement composition having a Blaine specific surface area of 3000 cm 2 /g or more, wherein the content of the inorganic mineral is 0.5 to 14.0 mass%, the total content of the inorganic mineral and the carbonate is more than 5 mass% and less than 15 mass%, and the total content of the cement clinker and the gypsum is 85 mass% or more and less than 95 mass%.
• the inorganic mineral is ground so that the ratio of the BET specific surface area of the ground inorganic mineral to the BET specific surface area of the inorganic mineral before grinding is 0.10 to 0.80.
• cement clinker As the cement clinker, two types of Portland cement clinker were used whose mineral composition calculated by the Bogue formula was the value shown in the following Table 1. The chemical composition of the cement used in the Bogue formula calculation was measured in accordance with the method described in JIS R 5204:2019 "Fluorescent X-ray analysis method for cement”.
• limestone and inorganic minerals were prepared.
• limestone fine powder (Blaine specific surface area value: 7470 cm 2 /g) was used, which was obtained by pulverizing limestone having a calcium carbonate content of 90% by mass or more and an aluminum oxide content of 1.0% by mass or less, and which satisfies the requirements for minor admixture components described in JIS R 5210 :2019 "Portland cement”.
• the inorganic mineral one containing allophane was used.
• Sekado P1 product name, manufactured by Shinagawa General Co., Ltd.
• Kanuma soil manufactured by Akagi Engei Co., Ltd.
• the measurement results of the insoluble residue, ignition loss (Ig. loss), and chemical components of each inorganic mineral are shown in Table 2.
• Ig. loss was measured according to the method of JIS R 5202:2010, and the insoluble residue was measured by the hydrochloric acid-sodium carbonate method.
• the chemical components were determined by chemical analysis using the fundamental parameter method of fluorescent X-rays according to JIS R 5202:2010 (equipment used: Rigaku ZSX-100e).
• R 2 O in Table 2 is the alkali content, calculated as Na 2 O content + 0.658 K 2 O content.
• Table 3 shows the measurement results of density, Blaine specific surface area, and BET specific surface area of the inorganic minerals before and after grinding (ground material).
• Blaine specific surface area was measured in accordance with the description in JIS R 5201:2015 "Physical measurement method for cement". The density value was measured using an automatic density meter (equipment: MAT-7000, Seishin Enterprise Co., Ltd.).
• the BET specific surface area was calculated from the measurement results of the amount of nitrogen gas adsorption in the relative pressure range of 0.05 to 0.35 using a BELSORP MINI (product name) manufactured by Microtrac Bell Co., Ltd., using the BET multipoint method with nitrogen gas.
• Table 3 shows the ratio of the BET specific surface area after crushing to the BET specific surface area before crushing, and the ratio of the Blaine specific surface area after crushing to the Blaine specific surface area before crushing. As shown in Table 3, the BET specific surface area of both Sekado P1 and Kanuma soil decreased and the Blaine specific surface area increased after crushing.
• the prepared cement composition was mixed with standard sand for cement strength testing provided by the Japan Cement Association as fine aggregate and water to prepare a hardened body in accordance with the method described in JIS R 5201:2015 "Physical test methods for cement”.
• the prepared hardened body was cured underwater in a thermostatic chamber at 20°C until it was 7 or 28 days old.
• the compressive strength of the above-mentioned hardened body at ages of 7 days and 28 days was measured in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement". The results are shown in Table 4.
• the compressive strength ratio is the ratio (percentage) of the compressive strength of the hardened body to the compressive strength of the reference hardened body.
• the reference hardened body was prepared by mixing ordinary Portland cement with standard sand for cement strength testing by the Japan Cement Association as fine aggregate and water in accordance with the method described in JIS R 5201:2015 “Physical Testing Methods for Cement".
• Base cement was obtained by adding gypsum in an amount of 2.0 mass% calculated as SO3 to the ground product of cement clinker B having the chemical composition shown in Table 1 and mixing. Then, limestone fine powder and inorganic minerals (before grinding) in Table 3 were added to the base cement as shown in Table 5, and mixed to prepare the cement compositions of Examples 6 and 7 and Comparative Examples 2 and 3. In Comparative Examples 2 and 3, the inorganic minerals in Table 3 were not mixed.

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