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US-20260125322-A1 - EARLY STRENGTH ENHANCER FOR HYDRAULIC COMPOSITIONS

US20260125322A1US 20260125322 A1US20260125322 A1US 20260125322A1US-20260125322-A1

Abstract

An early strength enhancer for hydraulic compositions contains calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less and improves the strength of hardened products of hydraulic compositions after, for example, 5 to 20 hours from preparation. A hydraulic composition contains the calcite, a hydraulic powder, and water. A method for producing the hydraulic composition includes a step of mixing the calcite, the hydraulic powder, and water.

Inventors

  • Hiroyuki Kawakami
  • Kohei Shimada
  • Yuto NAGOSHI

Assignees

  • KAO CORPORATION

Dates

Publication Date
20260507
Application Date
20231010
Priority Date
20221024

Claims (20)

  1. 1 . An early strength enhancer for hydraulic compositions, the early strength enhancer comprising: calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less as component (a).
  2. 2 . The early strength enhancer according to claim 1 , wherein an average secondary particle size of the component (a) is 1 μm or more and 20 μm or less.
  3. 3 . The early strength enhancer according to claim 1 , wherein secondary particles of the component (a) are spherical.
  4. 4 . The early strength enhancer according to claim 1 , further comprising: a dispersant as component (b).
  5. 5 . The early strength enhancer according to claim 4 , wherein the component (b) is a polycarboxylic acid-based polymer.
  6. 6 . The early strength enhancer according to claim 4 , wherein (a)/(b), which is a mass ratio of a content of the component (a) to a content of the component (b), is 50/50 or more and 99/1 or less.
  7. 7 . The early strength enhancer according to claim 1 , further comprising water.
  8. 8 . (canceled)
  9. 9 . A hydraulic composition, comprising: calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less as component (a), a hydraulic powder, and water.
  10. 10 . The hydraulic composition according to claim 9 , comprising the component (a) in an amount of 0.1 parts by mass or more and 2 parts by mass or less relative to 100 parts by mass of the hydraulic powder.
  11. 11 . The hydraulic composition according to claim 9 , further comprising: a dispersant as component (b).
  12. 12 . The hydraulic composition according to claim 11 , wherein the component (b) is a polycarboxylic acid-based polymer.
  13. 13 . The hydraulic composition according to claim 11 , wherein (a)/(b), which is a mass ratio of a content of the component (a) to a content of the component (b), is 1/99 or more and 99/1 or less.
  14. 14 - 20 . (canceled)
  15. 21 . A method for producing a hydraulic composition, the method comprising: mixing calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less as component (a), a hydraulic powder, and water.
  16. 22 . The method according to claim 21 , wherein the component (a) is mixed in an amount of 0.1 parts by mass or more and 2 parts by mass or less relative to 100 parts by mass of the hydraulic powder.
  17. 23 . The method according to claim 21 , further comprising: mixing a dispersant as component (b).
  18. 24 . The method according to claim 23 , wherein the component (b) is a polycarboxylic acid-based polymer.
  19. 25 . The method according to claim 23 , wherein the component (a), part or all of the component (b), and part or all of the water are mixed in advance, and mixed with the hydraulic powder in a water dispersion state where the component (a) is dispersed.
  20. 26 - 30 . (canceled)

Description

FIELD OF THE INVENTION The present invention relates to an early strength enhancer for hydraulic compositions and a hydraulic composition. BACKGROUND OF THE INVENTION Concrete may be required to develop demolding strength at an early stage when placed in formwork after mixing of a hydraulic powder such as Portland cement or the like, aggregate, and water. For example, when concrete for secondary tunnel linings is placed using travelling tunnel formwork, it is required to be capable of being demolded the next morning after placing from the viewpoint of productivity. Especially in winter, since the hardening reaction of concrete occurs slowly, there are many cases where high early strength is required. Further, at precast concrete production sites, so-called twice-a-day production in which placing in the same formwork is performed twice a day may be carried out to produce a large number of products with a small number of formwork. In that case, since the processes from placing to demolding of concrete need to be performed in a short period of time, there are many cases where high early strength is required. Raising concrete temperature by steam curing or heat curing is effective at obtaining high early strength, but steam curing or heat curing is not preferable from economic and environmental viewpoints, and thus, there is a need to obtain sufficiently high early strength at low temperatures. On the other hand, from the viewpoint of realizing a low-carbon society, attention is focused on so-called carbon recycling in which carbon dioxide is considered as a carbon resource and this is recovered and reused for various types of carbon compounds. One example of the materials for which carbon dioxide can be reused is calcium carbonate, and there is a need for technology to add high value to calcium carbonate. JP-A 2017-206428 discloses a hardening accelerator for cement having both functions of increasing compression strength and reducing shrinkage, the hardening accelerator being added during the preparation of concrete, and consisting of an aqueous suspension composed mainly of a colloid of fine nanosize particles of calcium carbonate with an average particle size of 10 to 400 nm and containing a specific amount of a specific surfactant component. SUMMARY OF THE INVENTION The present invention provides an early strength enhancer for hydraulic compositions which improves the strength of hardened products of hydraulic compositions after, for example, 5 to 20 hours from preparation, and a method for producing the same, and a hydraulic composition which improves the strength of hardened products of the hydraulic composition after, for example, 5 to 20 hours from preparation, and a method for producing the same. The present invention relates to an early strength enhancer for hydraulic compositions containing (a) calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less (hereinafter referred to as component (a)). Further, the present invention relates to a hydraulic composition containing component (a), a hydraulic powder, and water. Further, the present invention relates to a method for producing an early strength enhancer for hydraulic compositions including mixing component (a). Further, the present invention relates to a method for producing a hydraulic composition including mixing component (a), a hydraulic powder, and water. Further, the present invention relates to use as an early strength enhancer for hydraulic compositions of an agent containing component (a). Further, the present invention relates to a method for producing (a) calcite with a crystallite size in the (104) plane calculated by the Scherrer equation of 30 nm or less including the following step 1, step 2, and step 3, step 1: a step of mixing calcium hydroxide, water, and the following component (c) at a mass ratio of a mixing amount of calcium hydroxide to a mixing amount of component (c) (calcium hydroxide/(c)) of 10 or more and 100 or less to prepare a water dispersion of calcium hydroxide,component (c): one or more compounds selected from hydroxides of alkaline earth metals, sulfates, magnesium salts, zinc salts, organic acids and salts thereof, and polyacrylic acid and salts thereof,step 2: a step of blowing carbon dioxide gas into the water dispersion prepared in step 1 while keeping the water dispersion at 7° C. or more and 30° C. or less to produce a calcite water dispersion, andstep 3: a step of aging, storing, or drying the calcite water dispersion obtained in step 2 at 40° C. or less. The present invention provides an early strength enhancer for hydraulic compositions which improves the strength of hardened products of hydraulic compositions after, for example, 5 to 20 hours from preparation, and a method for producing the same, and a hydraulic composition which improves the strength of hardened products of the hydraulic composition after, for example, 5 to 20 hours from preparation, and a