Hydraulic composition

Abstract

To provide a hydraulic composition excellent in strength development after, for example, 4 to 24 hours from preparation, and a method for producing a cured body of the hydraulic composition.SOLUTION: A hydraulic composition according to the present invention comprises: (A) a Portland cement (Hereinafter referred to as a component (A)) containing 21.0 to 32.0 mass% of belite and having a mass ratio of the content of alite to that of belite (belite / alite) between 0.37 and 0.73; (B) water (Hereinafter referred to as a component (B)); and (C) a naphthalene-based dispersant, wherein the mass ratio (B) / (A) of the content of the component (B) to the content of the component (A) is 0.15 or more and 0.30 or less in the hydraulic composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydraulic composition and a method for producing a hardened product of the hydraulic composition. [Background technology]

[0002] In recent years, the e-commerce market has boomed due to changes in business practices. Logistics warehouses are an essential piece of infrastructure for e-commerce, and concrete support piles are used to secure these structures to the ground and protect them from natural disasters. Concrete piles are manufactured using a method called centrifugal molding, in which unhardened concrete prepared by adding water, hydraulic powder such as cement, aggregate, and a water-reducing agent is molded into a cylindrical shape by applying centrifugal force. Naphthalene sulfonic acid-based dispersants are mainly used as dispersants, as they have excellent properties that allow the concrete to be molded neatly into a cylindrical shape.

[0003] On the other hand, in response to the demand for national resilience, there is an increasing demand for high-bearing-capacity piles with increased bearing capacity per concrete pile, i.e., high-strength concrete piles. The strength of concrete is determined by the weight ratio of water to hydraulic powder (W / P), and the lower the W / P, the higher the strength of the hardened concrete (hydraulic composition). In Non-Patent Document 1, a naphthalene sulfonic acid-based dispersant is used in the water-binder ratio range of about 20%. However, when the water / hydraulic powder (W / P) ratio is reduced to obtain a hardened body with particularly high strength, the amount of naphthalene sulfonic acid-based dispersant required to be added increases significantly, and the excess dispersant in the system is intermittently adsorbed onto cement particles, causing a delay in the hardening of the unhardened hydraulic composition.

[0004] As described in Non-Patent Document 2, such an increase in the amount of naphthalenesulfonic acid-based dispersant added is thought to be caused by adsorption and burial (deactivation) in the cement hydration reaction products at the very early stage (immediately after contact with water to one hour later) of the hydration reaction, which is the hardening reaction of hydraulic powders such as Portland cement. It is generally known that this problem can be solved by using low-heat Portland cement with a high belite content, which is a cement mineral species with a relatively slow hydration reaction rate.

[0005] Patent Document 1 discloses a concrete-steel girder composite structure and a manufacturing method thereof in which prestress is effectively introduced without applying unnecessary stress to the steel girder, and the hardened concrete and steel girder are strongly bonded. Patent Document 2 discloses a high-expansion, high-strength cement composition and concrete that can achieve a large amount of expansion in the early stages of material life, maintain a stable amount of expansion over a long period of time, and are free from strength reduction or cracking due to expansion, making it possible to stably maintain high chemical prestress and high strength, as well as a method for producing a hardened concrete body using the same. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-30163 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-238439 [Non-patent literature]

[0007] [Non-Patent Document 1] Journal of Structural Engineering, Architectural Institute of Japan, Vol. 606, pp. 29-34, Architectural Institute of Japan, August 2006 [Non-patent document 2] Cement and Concrete Journal, Vol. 68, No. 1, pp. 75-81, Published by the Japan Cement Association, March 2015 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the use of low-heat Portland cement has the problem that the hydration reaction is excessively delayed, which reduces the strength development at early ages and ultimately the productivity of concrete.

[0009] The present invention provides a hydraulic composition that exhibits excellent strength development, for example, 4 to 24 hours after preparation, and a method for producing a hardened product of the hydraulic composition. [Means for solving the problem]

[0010] The present invention relates to a hydraulic composition comprising (A) Portland cement (hereinafter referred to as component (A)), which contains 21.0 to 32.0 mass% of belite and has a mass ratio of the alite content to the belite content (belite / alite) of 0.37 to 0.73, (B) water (hereinafter referred to as component (B)), and (C) a naphthalenesulfonic acid-based dispersant (hereinafter referred to as component (C)), wherein the mass ratio (B) / (A) of the content of component (A) to the content of component (B) in the hydraulic composition is 0.15 to 0.30.

[0011] The present invention also relates to a method for producing a hardened product of a hydraulic composition, which comprises the following steps: Step 1: A step of preparing a hydraulic composition by mixing (A) Portland cement (hereinafter referred to as component (A)) containing 21.0 mass % or more and 32.0 mass % or less of belite, with the mass ratio of the alite content to the belite content (belite / alite) being 0.37 or more and 0.73 or less, (B) water (hereinafter referred to as component (B)), and (C) a naphthalene sulfonic acid-based dispersant, in such a way that the mass ratio (B) / (A) of the mixed amount of component (A) to the mixed amount of component (B) is 0.15 or more and 0.30 or less. Step 2: A step of filling the hydraulic composition obtained in step 1 into a formwork. Step 3: A step of clamping the hydraulic composition filled into the formwork in step 2 by applying centrifugal force. Step 4: A step of allowing the hydraulic composition clamped in the mold in step 3 to set in the mold. [Effects of the Invention]

[0012] According to the present invention, there are provided a hydraulic composition that exhibits excellent strength development, for example, 4 to 24 hours after preparation, and a method for producing a hardened product of the hydraulic composition.

[0013] In recent years, the SDGs have been advocated for the realization of a sustainable society. The present invention has excellent strength development, for example, 4 to 24 hours after preparation, so it requires less heat for steam curing, which reduces CO2 emissions. By improving concrete productivity, it is thought that this technology could contribute to SDGs Nos. 7, 9, 11, 12, and 13, for example. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present inventors have found that the hydraulic composition of the present invention has excellent strength development, for example, 4 to 24 hours after preparation. The reason why such an effect is exhibited is not entirely clear, but is presumed to be as follows. As mentioned above, naphthalene sulfonate dispersants are known to accelerate the very early stage of cement hydration (immediately after contact with water to one hour) compared to polycarboxylic acid dispersants. The products of this hydration reaction grow while absorbing calcium ions in the system, lowering the calcium ion concentration in the system. The products of this hydration reaction compete with alite, which also grows while absorbing calcium ions and is involved in the development of strength in the early ages of concrete. This ultimately delays hydration and impairs strength development. In the present invention, by adjusting the belite content and the mass ratio of the alite content to the belite content (belite / alite) in the Portland cement, which is component (A), within a specific range, the apparent water / alite ratio is reduced while the hydration reaction at the very early stage is moderately suppressed in the hydraulic composition containing a naphthalenesulfonic acid-based dispersant, and the elution of calcium ions is promoted. At the same time, competition between the alite for calcium ions and hydration reaction sites is suppressed, which promotes the hydration reaction of the alite, and is therefore considered to have improved strength development.

[0015] [Hydraulic composition] The hydraulic composition of the present invention contains, as component (A), Portland cement containing 21.0 mass % or more and 32.0 mass % or less of belite, and the mass ratio of the alite content to the belite content (belite / alite) is 0.37 or more and 0.73 or less. From the viewpoint of strength development, the Portland cement of component (A) contains 21.0 mass% or more, preferably 21.5 mass% or more, and 32.0 mass% or less, preferably 31.0 mass% or less, more preferably 30.0 mass% or less, and even more preferably 29.0 mass% or less of belite (2CaO SiO2) in component (A).

[0016] From the viewpoint of strength development, the Portland cement of component (A) contains alite (3CaO·SiO2) in component (A) in an amount of preferably 44.5 mass% or more, more preferably 45.0 mass% or more, even more preferably 45.5 mass% or more, still more preferably 46.5 mass% or more, still more preferably 47.5 mass% or more, and preferably 54.5 mass% or less, more preferably 54.0 mass% or less, and even more preferably 53.5 mass% or less.

[0017] In the Portland cement of component (A), the mass ratio of the alite content to the belite content (belite / alite) is 0.37 or more, preferably 0.38 or more, more preferably 0.39 or more, and 0.73 or less, preferably 0.68 or less, more preferably 0.63 or less, and even more preferably 0.60 or less, from the viewpoint of strength development.

[0018] Examples of Portland cement include one or more types selected from ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, sulfate-resistant Portland cement, moderate-heat Portland cement, low-heat Portland cement, white Portland cement, blended cement, and ecocement. By mixing these Portland cements and adjusting the contents of belite and alite, it is possible to produce Portland cement, which is the component (A) of the present invention, containing 21.0 mass% or more and 32.0 mass% or less of belite and having a mass ratio of the alite content to the belite content (belite / alite) of 0.37 or more and 0.73 or less.

[0019] In addition to component (A), the hydraulic composition of the present invention may contain powders having posolan activity and / or latent hydraulic properties, such as blast furnace slag, fly ash, and silica fume, as well as non-hydraulic fine limestone powder. The hydraulic composition of the present invention may use blast furnace cement, fly ash cement, or silica fume cement, which is a mixture of blast furnace slag, fly ash, silica fume, or the like, as component (A).

[0020] The hydraulic composition of the present invention contains water as component (B). In the hydraulic composition of the present invention, the mass ratio (B) / (A) of the content of the component (A) to the content of the component (B) is 0.15 or more, preferably 0.18 or more, more preferably 0.21 or more, and 0.30 or less, preferably 0.28 or less, more preferably 0.26 or less, from the viewpoint of strength development.

[0021] The hydraulic composition of the present invention contains a naphthalenesulfonic acid-based dispersant as component (C). The naphthalenesulfonic acid-based dispersant preferably includes a naphthalenesulfonic acid-formaldehyde condensate or its salt. The naphthalenesulfonic acid-formaldehyde condensate or its salt is a condensate of naphthalenesulfonic acid and formaldehyde or its salt. The naphthalenesulfonic acid-formaldehyde condensate may be co-condensed with an aromatic compound capable of co-condensing with naphthalenesulfonic acid, such as methylnaphthalene, ethylnaphthalene, butylnaphthalene, hydroxynaphthalene, naphthalenecarboxylic acid, anthracene, phenol, cresol, creosote oil, tar, melamine, urea, sulfanilic acid, and / or derivatives thereof, as long as the performance is not impaired.

[0022] As the naphthalenesulfonic acid formaldehyde condensate or a salt thereof, commercially available products such as Mighty 150, Demol N, Demol RN, Demol MS, Demol SN-B, and Demol SS-L (all manufactured by Kao Corporation), Celflow 120, Labelin FD-40, and Labelin FM-45 (all manufactured by Daiichi Kogyo Co., Ltd.) can be used.

[0023] From the viewpoint of strength development, the naphthalenesulfonic acid formaldehyde condensate or its salt has a weight-average molecular weight of preferably 1,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, still more preferably 5,000 or more, and preferably 200,000 or less, more preferably 100,000 or less, even more preferably 80,000 or less, still more preferably 50,000 or less, and still more preferably 30,000 or less. The naphthalenesulfonic acid formaldehyde condensate may be in an acid state or a neutralized product.

[0024] The molecular weight of the naphthalenesulfonic acid formaldehyde condensate or its salt can be measured by gel permeation chromatography under the following conditions. [GPC conditions] Column: G4000SWXL + G2000SWXL (Tosoh) Eluent: 30mM CH3COONa / CH3CN=6 / 4 Flow rate: 0.7ml / min Detection: UV280nm Sample size: 0.2mg / ml Standard material: Nishio Kogyo Co., Ltd., sodium polystyrene sulfonate (monodisperse sodium polystyrene sulfonate: molecular weight: 206, 1,800, 4,000, 8,000, 18,000, 35,000, 88,000, 780,000) Detector: Tosoh Corporation UV-8020

[0025] A method for producing a naphthalenesulfonic acid-formaldehyde condensate or a salt thereof includes, for example, a method of obtaining a condensate by condensing naphthalenesulfonic acid with formaldehyde. The condensate may be neutralized. Furthermore, water-insoluble by-products produced during neutralization may be removed. Specifically, to obtain naphthalenesulfonic acid, 1.2 to 1.4 moles of sulfuric acid are used per mole of naphthalene, and the mixture is reacted at 150 to 165°C for 2 to 5 hours to obtain a sulfonated product. Next, formalin is added dropwise at 85 to 105°C over 3 to 6 hours so that the resulting sulfonated product contains 0.93 to 0.99 moles of formaldehyde per mole of the sulfonated product, and the condensation reaction is then carried out at 95 to 105°C. Furthermore, since the aqueous solution of the resulting condensate is highly acidic, a neutralization step can be carried out at 80 to 95°C to prevent corrosion of metals such as storage tanks. The neutralizing agent is preferably added in an amount of 1.0 to 1.1 moles relative to the naphthalenesulfonic acid and unreacted sulfuric acid. Furthermore, water-insoluble matters resulting from neutralization can be removed, preferably by separation by filtration. These steps yield an aqueous solution of a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate. This aqueous solution can be used as is as an aqueous solution of a naphthalenesulfonic acid-based dispersant. Furthermore, if necessary, the aqueous solution can be dried and powdered to obtain a powdered salt of a naphthalenesulfonic acid formaldehyde condensate, which can be used as a powdered naphthalenesulfonic acid-based dispersant. Drying and powdering can be performed by spray drying, drum drying, freeze drying, or the like.

[0026] The hydraulic composition of the present invention contains, from the viewpoint of strength development, preferably 0.1% by mass or more of component (C) relative to component (A), more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, and preferably 5.0% by mass or less, more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less.

[0027] The hydraulic composition of the present invention contains an aggregate as component (D). Examples of the aggregate include aggregates selected from fine aggregates and coarse aggregates. Examples of fine aggregates include those specified under number 2311 in JIS A 0203-2014. Examples of fine aggregates include river sand, land sand, mountain sand, sea sand, lime sand, silica sand, and crushed sands thereof, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregates (artificial and natural), and recycled fine aggregate. Examples of coarse aggregates include those specified under number 2312 in JIS A 0203-2014. Examples of coarse aggregates include river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregates (artificial and natural), and recycled coarse aggregate. The fine aggregate and coarse aggregate may be used in a mixture of different types, or a single type may be used.

[0028] When the hydraulic composition is concrete, the amount of coarse aggregate used is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, in terms of the strength of the hydraulic composition, reducing the amount of hydraulic powder such as cement used, and improving the fillability into forms, etc., and is preferably 100% or less, more preferably 90% or less, even more preferably 80% or less. 3 It is the ratio of the volume of coarse aggregate (including voids) in the concrete. When the hydraulic composition is concrete, the amount of fine aggregate used is preferably 500 kg / m from the viewpoint of improving the filling property into a formwork or the like. 3 More preferably, 600 kg / m 3 More preferably, 700 kg / m 3 and preferably 1000 kg / m 3 Less than or equal to 900 kg / m 3 The following is the result.

[0029] The hydraulic composition of the present invention may further contain other components, such as an air-entraining agent, a retarder, a foaming agent, a thickener, a foaming agent, a waterproofing agent, a fluidizing agent, an antifoaming agent, a shrinkage reducing agent, etc. (excluding components (A) to (D)).

[0030] The hydraulic composition of the present invention may be concrete or mortar. The hydraulic composition of the present invention is useful in any field, such as for self-leveling, refractories, plasters, lightweight or heavy concrete, air entraining, repair, prepacked, trampoline, ground improvement, grouting, and cold weather use. The hydraulic composition of the present invention develops strength in about 4 to 24 hours after preparation and can be quickly removed from a formwork, so it can be suitably used for concrete products, preferably for centrifugal molding.

[0031] The hydraulic composition of the present invention can be produced by mixing the (A), (B), and (C) components in such a way that the mass ratio (B) / (A) of the amount of component (A) to the amount of component (B) mixed is 0.15 or more and 0.30 or less. That is, the present invention provides a method for producing a hydraulic composition in which the (A), (B), and (C) components are mixed in such a way that the mass ratio (B) / (A) of the amount of component (A) to the amount of component (B) mixed is 0.15 or more and 0.30 or less. In the method for producing the hydraulic composition of the present invention, component (D) can be further mixed. The matters described for the hydraulic composition of the present invention can be applied as appropriate to the method for producing the hydraulic composition of the present invention. For example, specific examples and preferred embodiments of each component are the same as those for the hydraulic composition of the present invention. Furthermore, the content and mass ratio of each component in the hydraulic composition of the present invention can be applied to the method for producing the hydraulic composition of the present invention by replacing the content of each component with the mixing amount.

[0032] [Method for producing a hardened product of a hydraulic composition] The method for producing the hardened product of the hydraulic composition of the present invention comprises the following steps: The matters described for the hydraulic composition of the present invention can be applied appropriately to the method for producing the hardened product of the hydraulic composition of the present invention. Step 1: A step of preparing a hydraulic composition by mixing the (A) component, the (B) component, and the (C) component in a mass ratio (B) / (A) of the amount of the (A) component mixed to the amount of the (B) component mixed, of 0.15 or more and 0.30 or less. Step 2: A step of filling the hydraulic composition obtained in step 1 into a formwork. Step 3: A step of clamping the hydraulic composition filled into the formwork in step 2 by applying centrifugal force. Step 4: A step of allowing the hydraulic composition clamped in the mold in step 3 to set in the mold.

[0033] The method for producing the hardened product of the hydraulic composition of the present invention can include the following step 5, step 6, and step 7. Step 5: A step of steam curing the hydraulic composition set in step 4 in a formwork. Step 6: After step 5, a step of cooling the hydraulic composition and removing it from the formwork. Step 7: A step of curing the hardened hydraulic composition obtained in step 6 at room temperature and normal pressure.

[0034] In step 1, the hydraulic composition of the present invention can be prepared. In step 1, component (D) may also be mixed. In step 1, the matters described in relation to the hydraulic composition of the present invention can be applied as appropriate. For example, specific examples and preferred embodiments of each component are the same as those of the hydraulic composition of the present invention. In addition, the content and mass ratio of each component in the hydraulic composition of the present invention can be applied to the method for preparing the hydraulic composition of the present invention by replacing the content of each component with the mixing amount.

[0035] In step 2, the hydraulic composition obtained in step 1 is filled into the formwork by, for example, discharging the kneaded hydraulic composition from the kneading means and manually pouring it into the formwork and leveling it.

[0036] In step 3, the hydraulic composition filled in the form is clamped by applying centrifugal force, and it is preferable to change the centrifugal force at least once during this process. In step 3, the hydraulic composition can be clamped by applying centrifugal force that changes stepwise.

[0037] In step 3, the hydraulic composition filled in the formwork is preferably clamped under a centrifugal force of 0.5 G or more. The centrifugal force in centrifugal molding is preferably 0.5 G or more and 30 G or less, more preferably 25 G or less. From the viewpoints of energy cost reduction and moldability, it is preferable to maintain the centrifugal force in the range of 15 G or more and 30 G or less, further 25 G or less (also called high centrifugal force) for at least 1 minute.

[0038] Compaction by centrifugal force is carried out, for example, at a centrifugal force of 0.5 G to 30 G, for preferably 5 minutes or more, more preferably 7 minutes or more, even more preferably 9 minutes or more, and preferably 40 minutes or less. From the viewpoint of compacting the molded body smoothly, compaction by maintaining a high centrifugal force, for example, a centrifugal force of 20 G or more, is preferably carried out for 1 minute or more, more preferably 3 minutes or more, even more preferably 5 minutes or more, and preferably 15 minutes or less.

[0039] Compaction using centrifugal force can be carried out in stages, and from the viewpoint of formability, a method in which the centrifugal force G is increased stepwise is preferred. Compaction can be carried out under the following step conditions until the desired centrifugal force is reached. For example, in the case of five stages, it is preferable to carry out the following: (1) the first stage, an initial speed of 0.5 G or more but less than 2 G, for more than 0 minutes but not more than 15 minutes; (2) the second stage, a second speed, a centrifugal force of 2 G or more but less than 5 G, for more than 0 minutes but not more than 15 minutes; (3) the third stage, a third speed, a centrifugal force of 5 G or more but less than 10 G, for more than 0 minutes but not more than 15 minutes; (4) the fourth stage, a fourth speed, a centrifugal force of 10 G or more but less than 20 G, for more than 0 minutes but not more than 15 minutes; and (5) the fifth stage, a fifth speed, a centrifugal force of 20 G or more but not more than 30 G, for more than 0 minutes but not more than 15 minutes.

[0040] In step 4, the hydraulic composition obtained in step 3 is solidified. Specifically, the composition is cured in air for 3 to 4 hours after mixing.

[0041] In step 5, the hardened concrete placed in the formwork obtained in step 4 is steam cured. The curing conditions are preferably a pre-curing step of leaving the concrete at room temperature (20°C) for 1 to 4 hours, followed by steam curing at a temperature between 60°C and 85°C. Steps 5 and 6 can be carried out consecutively under temperature control. Specific curing conditions are as follows: in step 5, the ambient temperature of the formwork is raised to 60°C or higher and 85°C or lower at a rate of 10°C or higher and 30°C or lower per hour, and the raised temperature is maintained for 2 hours or higher and 8 hours or lower; then, in step 6, the temperature is lowered to room temperature, for example, 20°C, at a rate of 5°C or higher and 20°C or lower per hour, and the molded body is demolded. An example of preferred conditions is a method in which the molded body is left at room temperature, for example, 20°C, for 3 hours, heated at a rate of 20°C / hour, and held at 80°C for 6 hours (step 5), then cooled to room temperature at 10°C / hour, and demolded after 20 to 30 hours (step 6). It is also possible to further cure the material in an autoclave at 180°C.

[0042] In step 7, the set hydraulic composition obtained in step 6 is cured at room temperature and atmospheric pressure. Specifically, it is stored at 20°C and atmospheric pressure.

[0043] The method for producing a hardened hydraulic composition of the present invention may be such that the time from the start of preparation of the hydraulic composition to demolding in step 6 is 8 hours or more and 30 hours or less. Here, the start of preparation of the hydraulic composition refers to the time when the hydraulic powder first comes into contact with water.

[0044] The hardened product of the hydraulic composition obtained by the production method of the present invention can be used as a centrifugally molded concrete product, specifically, a pile, a pole, a Hume pipe, etc. [Example]

[0045] The materials used in the examples and comparative examples are shown below. <Component (A) or Component (A')> Ordinary Portland cement (manufactured by Taiheiyo Cement Corporation, belite content 18.0% by mass, alite content 56.0% by mass, specific gravity 3.16) and low-heat Portland cement (manufactured by Taiheiyo Cement Corporation, belite content 55% by mass, alite content 27.0% by mass, specific gravity 3.22) were charged into a Hobart mixer specified in JIS R 5201 in amounts equivalent to parts by mass per part by mass of the total Portland cement listed in Table 1, and mixed at 140 rpm for 1 minute to prepare Portland cements of component (A) or (A') (comparison component to component (A)). Table 1 also shows the belite content (mass%) and alite content (mass%) in each Portland cement prepared, calculated from the blended parts by mass of each Portland cement according to the following formula. Table 1 also shows the mass ratio of alite to belite (belite / alite) in each Portland cement prepared. *Belite content (mass%) = Mixed mass parts of ordinary Portland cement x 0.18 (belite content of ordinary Portland cement) + Low-heat Portland cement blend mass x 0.55 (belite content of low-heat Portland cement) *Alite content (mass%) = Mixed mass parts of ordinary Portland cement x 0.56 (belite content of ordinary Portland cement) + Low-heat Portland cement blend mass x 0.27 (belite content of low-heat Portland cement)

[0046] [Table 1]

[0047] <(B) component> Water: Tap water (Wakayama City tap water, specific gravity 1.00) <(C) component> Naphthalene sulfonic acid dispersant: Mighty 150 (Kao Corporation, specific gravity 1.20) <Component (C') (comparison component of component (C)> Polycarboxylic acid dispersant: sodium salt of methacrylic acid / methoxypolyethylene glycol (25) monomethacrylate = 75 / 25 mol% copolymer, weight average molecular weight = 40,000 <(D) component> Fine aggregate: Mountain sand (produced in Joyo, Kyoto City, coarseness ratio 2.73, surface dry specific gravity 2.58)

[0048] Preparation of hydraulic composition slurry The prepared (A) or (A') component and (D) component were added in parts by mass relative to 1 part by mass of the total hydraulic composition slurry shown in Table 2, and mixed at 140 rpm for 15 seconds. Next, the (B) component was added in parts by mass relative to 1 part by mass of the total hydraulic composition slurry shown in Table 2, and the (C) or (C') component was added in an amount (% by mass) relative to the parts by mass of the (A) component shown in Table 2, and mixed for an additional 3 minutes at 140 rpm to obtain a hydraulic composition slurry. The content of the naphthalenesulfonic acid-based dispersant is shown as the solid content. Table 2 also shows the mass ratio (B) / (A) of the content of the (A) component to the content of the (B) component in the hydraulic composition slurry.

[0049] (2) Evaluation of strength development of hydraulic composition slurry 20 g of the hydraulic composition slurry prepared as described in (1) was weighed and filled into a 20 ml closed HDPE ampoule. Using an isothermal calorimeter TAM Air (manufactured by TA Instruments-Waters LLC), the time (minutes) from contact with water to the second hydration exothermic peak was recorded and used as an index of strength development. The shorter this time, the better the strength development at the early hydration age is evaluated. The results are shown in Table 2.

[0050] [Table 2]

[0051] In Table 2, Examples 1 to 4 showed a shorter time from contact with water to the second hydration exothermic peak than Comparative Examples 2 to 6, i.e., superior strength development. This is believed to be due to the fact that adjusting the belite content and the mass ratio (belite / alite) of the alite content to the belite content in the Portland cement within a specific range moderately suppresses the very early hydration reaction in systems containing naphthalenesulfonic acid-based dispersants, lowering the apparent water / alite ratio, promoting calcium ion elution, and suppressing competition between alite for calcium ions and hydration sites, thereby accelerating the alite hydration reaction. Furthermore, in Comparative Examples 1 and 7, which used polycarboxylic acid-based dispersants, no improvement in strength development was confirmed by adjusting the belite content and the mass ratio (belite / alite) of the alite content to the belite content in the Portland cement. This is believed to be due to the fact that the polycarboxylic acid-based dispersant exhibits a higher calcium ion chelating ability than the naphthalenesulfonic acid-based dispersant, delaying the alite hydration reaction itself.

Claims

1. A hydraulic composition containing (A) Portland cement (hereinafter referred to as component (A)) containing 21.0% by mass or more and 32.0% by mass or less of belite, and having a mass ratio of the content of alite to the content of belite (belite / alite) of 0.37 or more and 0.73 or less, (B) water (hereinafter referred to as component (B)), and (C) a naphthalene sulfonic acid-based dispersant (hereinafter referred to as component (C)), wherein in the said hydraulic composition, the mass ratio (B) / (A) of the content of component (A) to the content of component (B) is 0.15 or more and 0.30 or less.

2. The hydraulic composition according to claim 1, wherein component (C) is contained in an amount of 0.1% by mass or more and 5.0% by mass or less based on component (A).

3. The hydraulic composition according to claim 1 or 2, further containing (D) aggregate.

4. The hydraulic composition according to claim 1 or 2, which is for centrifugally formed concrete.

5. A method for producing a hardened body of a hydraulic composition, comprising the following steps. Step 1: Mixing (A) Portland cement (hereinafter referred to as component (A)) containing 21.0% by mass or more and 32.0% by mass or less of belite, and having a mass ratio of the content of alite to the content of belite (belite / alite) of 0.37 or more and 0.73 or less, (B) water (hereinafter referred to as component (B)), and (C) a naphthalene sulfonic acid-based dispersant so that the mass ratio (B) / (A) of the mixing amount of component (A) to the mixing amount of component (B) is 0.15 or more and 0.30 or less to prepare a hydraulic composition. Step 2: Filling the hydraulic composition obtained in Step 1 into a mold. Step 3: Applying centrifugal force to the hydraulic composition filled in the mold in Step 2 to clamp the mold. Step 4: Curing the hydraulic composition clamped in the mold in Step 3 in the mold.

6. The method for producing a hardened body of a hydraulic composition according to claim 5, further comprising the following Step 5. Step 5: A step of subjecting the hydraulic composition solidified in Step 4 to steam curing in a mold.