JP6200319B2 - Method for producing cured body of hydraulic composition - Google Patents

Description

  The present invention relates to a method for producing a cured body of a hydraulic composition that can be demolded in a short time.

Concrete products are kneaded with materials such as hydraulic powder (eg cement), aggregate, water and water reducing agent (dispersant, admixture), and placed in various forms according to the purpose, and cured (hardened). It becomes a product through the process. Expressing high strength in the initial age is important from the viewpoint of productivity (improving the rotation rate of the formwork), and measures such as the following methods are taken for that purpose.
(1) Use early-strength cement as cement.
(2) The amount of water in the cement composition is reduced using various polycarboxylic acid compounds as water reducing agents.
(3) Add inorganic / organic curing accelerators (early strengthening agents, setting accelerators, etc.) that promote cement hydration.
(4) Steam curing is performed as a curing method.

Today, there are cases where further shortening of the curing process is desired due to demands for higher productivity, for example, it may be necessary to develop demoldable strength within a curing time of 12 hours or less. Generally, the demoldable strength is required to be 8 to 15 [N / mm ² ], although it depends on the size of the cured body of the hydraulic composition. A concrete production method that develops demoldable strength at an early stage is highly desired in the market because it leads to an improvement in productivity. In addition, the curing time is usually shortened by steam curing, but this leads to a rise in energy costs associated with the use of steam, and from the viewpoint of energy cost reduction (shortening of steam curing time and curing temperature). There is an urgent need for a method of producing concrete that develops demoldable strength at an early stage.

  Patent Document 1 discloses a cement composition containing a polycarboxylic acid copolymer and an alkanolamine compound and having high water reduction performance and excellent early strength. A copolymer of polyethylene glycol methyl ether methacrylate and acrylic acid can be cited as an example, and by using this copolymer and HPEDA (N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine). It is described that the compressive strength after 24 hours at 10 ° C. is improved.

  Patent Document 2 discloses an early hardening agent for a hydraulic composition that can improve the initial cured property (setting time / σ1) of ultra-high-strength concrete.

  In Patent Document 3, the use of early-strength Portland cement, the mixing of an inorganic hardening accelerator (for example, calcined alum), the water-cement ratio of concrete is set to 30 to 45% by weight, and from casting to demolding. A concrete product manufacturing method characterized by performing steam curing in a range of 70 ° C. or less and an integrated temperature (maturity) of 210 to 290 ° C. · hr is disclosed.

  Accumulated temperature is known as an index for relating the strength of the hydraulic composition in consideration of material age and temperature. Non-Patent Document 1 describes that the intensity is a function of the integrated temperature. On the other hand, in the Standard Specification (Japan Society of Civil Engineers), the relationship between accumulated temperature and strength is not uniform depending on the materials used, the composition, the degree of wetness, etc., so it should be confirmed in advance by testing. Have been described.

JP2011-236127A JP 2011-116587 A JP 2000-301531 A

Masamichi Hayashi, Koichi Hamada “Concrete Engineering Durability / Details in Cold Concrete”, published by Sankaidou Co., Ltd., March 18, 2003, pages 145-147

  In the method using steam curing, the production using the same mold has a limit of 1 to 2 cycles per day. Therefore, many molds are required to reach the target number of production, and it is strongly required to improve the productivity by increasing the rotation efficiency of the molds in order to reduce the mold cost. Further, if the demolding time can be shortened without adding a component for increasing the initial strength as in Patent Documents 1 and 2, it is more desirable in terms of cost.

  The present invention provides a method for producing a cured body of a hydraulic composition that has good workability, can provide strength in a short time, and can be demolded in a short time.

The present invention relates to a method for producing a cured product of a hydraulic composition including the following steps (1) to (4).
Step (1) A component containing the copolymer (A), hydraulic powder, aggregate and water is kneaded so that the water / hydraulic powder ratio (mass ratio) is 0.35 or more and 0.45 or less. Preparing a hydraulic composition.
Process (2) The process of putting a hydraulic composition in a formwork.
Step (3) A step of curing the hydraulic powder in the mold with a curing time of 8 hours or less so that the accumulated temperature is 260 to 300 [° C./hour].
Step (4) A step of removing the cured body from the mold after curing.
<Copolymer (A)>
A monomer a1 represented by the following general formula (A1) and a monomer a2 represented by the following general formula (A2), a monomer a1 constituting the copolymer (A), A copolymer in which the molar ratio of reaction units of the monomer a2 is monomer a1 / monomer a2 = 60/40 or more and 90/10 or less.

(In the formula, M represents a hydrogen atom, alkali metal, alkaline earth metal (1/2 atom), ammonium, alkylammonium or substituted alkylammonium)

(Wherein R ¹ , R ² and R ³ are the same or different and represent a hydrogen atom or a methyl group, R ⁴ represents an alkyl group having 1 to 3 carbon atoms, and Y represents CH ₂ O, CH ₂ CH _{2 represents} O or COO, and n represents a number of 20 or more and 80 or less)

The production method of the present invention is excellent in workability because a moderate viscosity is imparted to a hydraulic composition having a specific water / hydraulic powder ratio, and is known as a fast-strength cement or fast-strength known in the art. Even without the use of an agent, the strength of concrete can be increased in a short time, and demolding can be performed at an early stage.
The copolymer (A) used in the present invention is excellent in performance as a water reducing agent, and the method of the present invention using the copolymer (A) under a predetermined condition can reduce the energy cost while maintaining the water reducing agent cost. One of the methods.

  Cement dispersants are required to reduce concrete viscosity from the viewpoint of improving workability and to improve initial strength from the viewpoint of productivity. Recently, polycarboxylic acid-based dispersants are often used as cement dispersants. The polycarboxylic acid-based dispersant has a portion derived from an unsaturated carboxylic acid as an adsorbing group and a portion derived from a steric repulsion group such as methoxypolyethylene glycol methacrylate. So far, polycarboxylic acid-based dispersants have been adjusted by changing the ratio of adsorbing groups or changing the length of steric repulsion groups as factors for adjusting viscosity and initial strength.

  However, when the number of adsorbing groups is increased, the viscosity decreases, but the initial strength decreases, and when the steric repulsion group is lengthened, the initial strength increases, but the viscosity increases. Accordingly, it has been considered in the art that it is difficult to develop the initial strength while maintaining the viscosity of the hydraulic composition appropriately.

  As a polycarboxylic acid-based dispersant, a polymer having a component of methacrylic acid and methoxypolyethylene glycol methacrylate (referred to as MAA polymer) has been often used.

  The copolymer (A) used in the present invention is a polymer comprising acrylic acid and an ester compound or ether compound having an alkoxypolyalkylene glycol chain as constituent monomers. Although the copolymer (A) has been considered to have almost the same properties as the MAA polymer, a copolymer with a very limited structure has a water / hydraulic powder ratio (mass ratio) of 0.35. As described above, when used in a hydraulic composition of 0.45 or less, initial strength increases without increasing the viscosity when cured under a specific cumulative temperature condition, compared to the case where a MAA polymer dispersant is used. I found out. Moreover, in the present invention, an unexpected effect is obtained in that the initial strength is higher than that of the MAA polymer when the maturity is the same within a curing time of 8 hours or less. In other words, the present invention can achieve both of the two effects of maintaining the viscosity of the hydraulic composition and improving the initial strength, which are conventionally considered to be difficult to achieve due to a trade-off relationship.

  The reason for this is not clear, but the copolymer (A) according to the present invention has a flexible main chain and a small volume compared to the MAA polymer, so that the coated area on the cement surface is reduced. Presumed to be adsorbed on the surface. Furthermore, from the DLVO theory and Langmuir's adsorption isotherm, it is common that when the affinity with the solvent is high, the time to reach saturated adsorption is short and the saturated adsorption amount decreases, and the copolymer (A) is MAA. It is presumed that the affinity with the solvent is higher than that of the system polymer, the time for reaching the saturated adsorption is short, and the saturated adsorption amount is small. It is said that the very early hydration reaction of cement is inhibited in places where dispersants are adsorbed (Reference: Rheology and reactivity of cementitious binders with plasticizers, p40, Fig.2.18, by Hedda Vikan, 2006). On February 16, Norwegian University of Science and Technology, Doctoral thesis), the copolymer (A) according to the present invention has a short time to reach saturated adsorption and a small amount of saturated adsorption. It is presumed that the sum reaction is hard to be inhibited and the strength is higher than that of the MAA copolymer in a limited period when the cement strength starts to develop. Regarding the viscosity, it is presumed from the DLVO theory that when the dispersant has a high affinity with the solvent, the energy that can contribute to the dispersion and the repulsive force are improved, and the viscosity of the dispersion system is reduced. And in the region where the water / hydraulic powder ratio selected in the present invention is 0.35 or more and 0.45 or less, the dispersant structure has a great influence on the viscosity of the dispersion system. Presumed to have appeared.

<Copolymer (A)>
[Monomer a1]
Monomer a1 is acrylic acid or a salt thereof. In the case of forming a salt, examples of the counter ion include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, an alkylammonium ion, or a substituted alkylammonium ion. From the viewpoint of reactivity with the monomer a2, acrylic acid A compound selected from sodium, potassium acrylate, and calcium acrylate is preferable, and sodium acrylate is more preferable.

[Monomer a2]
In general formula (A2), R ¹ is preferably a hydrogen atom. In general formula (A2), R ² is preferably a methyl group. In general formula (A2), R ³ is preferably a hydrogen atom. In general formula (A2), R ⁴ is preferably a methyl group. In general formula (A2), Y is preferably COO.

  In general formula (A2), n is the average number of added moles of an alkyleneoxy group, and is 20 or more and 80 or less, preferably 23 or more, more preferably 40 or more from the viewpoint of 24 hour strength, dispersibility, and workability. 60 or more is more preferable. And 75 or less is preferable and 70 or less is more preferable.

As monomer a2, methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, ethoxypolyethyleneglycol, ethoxypolyethylenepolypropyleneglycol, propoxypolyethyleneglycol, propoxypolyethylenepolypropyleneglycol, etc., one-end alkyl-capped polyalkyleneglycol and acrylic acid or methacrylic acid Esterified products, addition of ethylene oxide and / or propylene oxide to acrylic acid or methacrylic acid, 2-hydroxyethyl vinyl ether, allyl alcohol, hydroxybutyl vinyl ether, methallyl alcohol, 3-methyl-3-buten-1-ol Unsaturated polyalkylene glycols obtained by adding alkylene oxides to alkenyl alcohols such as It can be used ether.
From the viewpoint of the stability of the compound, a methacrylic acid ester compound of one end alkyl-capped polyethylene glycol or an unsaturated polyalkylene glycol ether is preferred, and a methacrylic acid ester compound of one-end alkyl capped polyethylene glycol is more preferred.

When the monomer a2 has both an ethyleneoxy group (R ³ in the general formula (A2) is a hydrogen atom) and a propyleneoxy group (R ³ in the general formula (A2) is a methyl group), random addition, Either block addition or alternate addition can be used.

[Copolymerization ratio of copolymer (A)]
In the copolymer (A), the molar ratio of the monomer a1 and monomer a2 constituting the copolymer (A) is such that the monomer a1 / monomer a2 = 60/40 or more, 90 / 10 or less. The molar ratio of monomer a1 / monomer a2 is preferably 85/15 or less, and more preferably 80/20 or less, from the viewpoint of initial dispersibility and fluidity retention. And 65/35 or more is preferable and 70/30 or more is more preferable.

[Other monomers]
The copolymer (A) may be produced using other copolymerizable monomers within the range not impairing the effects of the present invention. The total of monomer a1 and monomer a2 is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, and 100% by mass or less from the viewpoint of improving the initial fluidity. Is more preferable, and may be 100% by mass.

  Specific examples of other monomers include (i) monocarboxylic acids such as methacrylic acid and crotonic acid or salts thereof (for example, alkali metal salts, alkaline earth metal salts, ammonium salts, and hydroxyl groups may be substituted). Good mono-, di-, trialkyl (2 to 8 carbon atoms) ammonium salts) or esters thereof. Further, for example, (ii) dicarboxylic acid monomers such as maleic acid, itaconic acid and fumaric acid, or anhydrides or salts thereof (for example, alkali metal salts, alkaline earth metal salts, ammonium salts, hydroxyl groups are substituted) Mono, di, trialkyl (C 2 or more, 8 or less) ammonium salt) or ester may be mentioned. Among these, methacrylic acid, maleic acid and maleic anhydride are preferable, and methacrylic acid or alkali metal salts thereof are more preferable.

[Weight average molecular weight of copolymer (A)]
The weight average molecular weight of the copolymer (A) is preferably 5,000 or more, more preferably 20,000 or more, and more preferably 40,000 or more from the viewpoint of initial fluidity. The weight average molecular weight of the copolymer (A) is preferably 300,000 or less, more preferably 200,000 or less, and more preferably 150,000 or less. The weight average molecular weight of the copolymer (A) is measured under the GPC conditions described in the examples.

[Method for Producing Copolymer (A)]
The copolymer (A) can be produced by a method such as a solution polymerization method or a bulk polymerization method using a polymerization initiator.
Examples of the solvent used in the solution polymerization method include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, ethyl acetate, acetone, and methyl ethyl ketone. From the viewpoint of handling and simplification of reaction equipment, water and methyl alcohol, ethyl alcohol and isopropyl alcohol are preferable, and water is more preferable. As the polymerization initiator, an aqueous polymerization initiator is preferable, and an ammonium salt or alkali metal salt of persulfuric acid, hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis ( Water-soluble azo compounds such as 2-methylpropionamido) dihydrate are used. For solution polymerization using a non-aqueous solvent, peroxides such as benzoyl peroxide and lauroyl peroxide, aliphatic azo compounds such as azobisisobutyronitrile, and the like are used. Moreover, accelerators, such as sodium hydrogen sulfite and an amine compound, can also be used in combination with a polymerization initiator. For the purpose of adjusting the molecular weight, chain transfer agents such as 2-mercaptoethanol, mercaptoacetic acid, 1-mercaptoglycerin, mercaptosuccinic acid and alkyl mercaptan can be used in combination. As the polymerization initiator for bulk polymerization, a peroxide such as benzoyl peroxide and an aliphatic azo compound such as azobisisobutyronitrile are preferable. The polymerization temperature is preferably 40 ° C. or higher and 160 ° C. or lower.

  Examples of the polymerization method include solution polymerization methods described in JP-A Nos. 62-119147 and 62-78137. That is, it is produced by mixing and polymerizing the monomer a1 and the monomer a2 in the above ratio in an appropriate solvent. An example of the manufacturing method of a copolymer (A) is shown. A predetermined amount of water is charged into a reaction vessel, the atmosphere is replaced with an inert gas such as nitrogen, and the temperature is raised. Prepare a monomer a1, monomer a2 and chain transfer agent mixed and dissolved in water and a polymerization initiator dissolved in water in a reaction vessel over 0.5 to 5 hours Dripping into. At that time, each monomer, chain transfer agent and polymerization initiator may be dropped separately, or a mixed solution of monomers can be charged in a reaction vessel in advance and only the polymerization initiator can be dropped. is there. That is, the chain transfer agent, the polymerization initiator, and other additives may be added as an additive solution separately from the monomer solution, or may be added to the monomer solution after being added. From the viewpoint of stability, it is preferable to supply the reaction system as an additive solution separately from the monomer solution. Further, aging is preferably performed for a predetermined time. The polymerization initiator may be added dropwise at the same time as the monomer, or may be added in portions, but it is preferable to add in portions in terms of reducing unreacted monomers. For example, in the total amount of the polymerization initiator to be finally used, a polymerization initiator of 1/2 or more and 2/3 or less is added simultaneously with the monomer, and the remainder is added for 1 hour or more and 2 hours or more after the completion of the monomer dropping. Thereafter, it is preferably added after aging. If necessary, the copolymer (A) is obtained by further neutralizing with an alkali agent (such as sodium hydroxide) after completion of aging.

<Hydraulic powder>
Hydraulic powder is a powder that has the property of curing by reacting with water, and a single substance does not have curability, but when two or more types are combined, a hydrate is formed by interaction through water. It is a powder that hardens and hardens. Examples of the hydraulic powder include ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, mixed cement, and eco-cement (for example, JIS R5214). The concrete used in the present invention may include gypsum, blast furnace slag, fly ash, silica fume, and the like as hydraulic powder other than cement. From the viewpoint of material cost, ordinary cement and mixed cement are preferable, and ordinary cement is more preferable.

<Aggregate>
Examples of the aggregate include fine aggregate and coarse aggregate. The fine aggregate is preferably mountain sand, land sand, river sand and crushed sand, and the coarse aggregate is preferably mountain gravel, land gravel, river gravel and crushed stone. Depending on the application, lightweight aggregates may be used. The term “aggregate” is based on “Concrete Overview” (published on June 10, 1998, published by Technical Shoin).

<Water>
In the present invention, a hydraulic composition containing water is prepared. The ratio of the water / hydraulic powder of the hydraulic composition according to the present invention is 0.35 or more and 0.45 or less from the viewpoint of demolding strength and workability. Among these, the ratio of water / hydraulic powder is preferably 0.40 or less.

<Other ingredients>
In the hydraulic composition according to the present invention, a fast-strength cement or a fast-strengthening agent can be used. Examples of the early strengthening agent include triethanolamine, BASF Corporation X-seed (registered trademark, calcium silicate hydrate), calcium thiocyanate, and the like.

  The hydraulic composition according to the present invention may be concrete or mortar. The hydraulic composition of the present invention can be used for self-leveling, for refractory, for plaster, for light or heavy concrete, for AE, for repair, for prepacked, for tramy, for ground improvement, for grout, for cold, etc. It is also useful in the field. From the standpoint that the time required to reach the required strength of the hydraulic composition can be shortened and the mold can be removed from the mold at an early stage, it is preferably used for concrete products such as concrete vibration products and centrifugal molded products.

<Manufacturing method>
This invention is a manufacturing method of the hardening body of a hydraulic composition including the following process (1)-(4).
Step (1) A component containing hydraulic powder, water, aggregate and copolymer (A) is kneaded so that the water / hydraulic powder ratio (mass ratio) is 0.35 or more and 0.45 or less. Preparing a hydraulic composition.
Process (2) The process of putting a hydraulic composition in a formwork.
Step (3) A step of curing the hydraulic powder in the mold with a curing time of 8 hours or less so that the accumulated temperature (maturity) is 260 or more and 300 or less [° C./hour].
Step (4) A step of removing the cured body from the mold after curing.

  In the step (1), it is preferable to add a component containing water and the copolymer (A) to a mixture obtained by kneading a hydraulic powder and an aggregate in advance, and knead. The copolymer (A) is preferably used in a proportion of 0.35 parts by mass or more and 0.45 parts by mass or less with respect to hydraulic powder, preferably 100 parts by mass of cement. Further, the hydraulic powder obtained in the step (1) has a water / hydraulic powder ratio (mass ratio) of 0.35 or more and 0.45 or less, from the viewpoint of shortening the time to reach the demolding strength. The water / hydraulic powder ratio (mass ratio) is more preferably 0.40 or less.

  In the step (2), the hydraulic composition kneaded in the step (1) is poured into an arbitrary mold. Examples of the mold frame include a steel mold frame and a wooden mold frame. Examples of the wooden mold frame include a plywood mold frame, a log mold frame, and a decorative mold frame.

  In the step (3), the hydraulic powder in the mold is cured in a curing time of 8 hours or less so that the accumulated temperature (maturity) is 260 or more and 300 or less [° C./hour]. A shorter curing time is preferable in terms of production efficiency. In the present invention, the curing time can be selected from within 7 hours, further within 6 hours, and over 4 hours, further over 5 hours.

Here, the accumulated temperature (maturity) is defined in JASS5 (Architectural Institute of Japan Architectural Construction Standard Specification, Reinforced Concrete Construction Standard Specification), and is the product of the sum of the temperature history of concrete and time.
In the production method of the present invention, from the viewpoint of improving the initial strength development, the integrated temperature is 260 [° C./hour] or more and 300 [° C./hour] or less, and the integrated temperature is preferably 280 [° C./hour] or more, 290 [° C. · hour] or more is more preferable.

  Step 4 removes the cured body from the mold. Make sure there are no defects such as cracks, cold joints, or jumpers when removing the mold.

  In the present invention, the time from the start of kneading the hydraulic composition in step 1 to the demolding of the cured product in step (4), the so-called demolding time, can be shortened. For example, this time is within 7 hours, It can be within 6 hours.

<Example of copolymer production>
A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube and a reflux condenser was charged with 160 g of water, the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 78 ° C. under a nitrogen atmosphere. Next, methoxy polyethylene glycol monomethacrylate (ethylene oxide average addition mole number 23, in general formula (A2), R ¹ is a hydrogen atom, R ² is a methyl group, R ³ is a hydrogen atom, R ⁴ is a methyl group, Y is COO, a monomer aqueous solution in which 147.22 g of n) and acrylic acid (manufactured by Sigma Aldrich Japan Co., Ltd.) 25.45 g are mixed and dissolved in 96.9 g of water, and 3-mercaptopropionic acid (Sigma Aldrich Japan Co., Ltd.) A three-part solution of 1.42 g dissolved in 16 g of water and 1.7 g of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 15 g of water was added dropwise over 1.5 hours. did. After completion of the dropwise addition, an aqueous solution obtained by dissolving 0.57 g of ammonium persulfate in 7.5 g of water was further added dropwise over 0.5 hours. Thereafter, the temperature was maintained at 78 ° C. for 1 hour, and aging was performed to complete the polymerization reaction. The aqueous solution containing the obtained reaction mixture was neutralized with a 48% aqueous sodium hydroxide solution to obtain an aqueous solution of copolymer 1-2 having a pH of 6.1 and a weight average molecular weight of 57,700. Other copolymers shown in Table 2 were produced in the same manner. In Table 2, monomers that do not belong to monomer a1 are also shown in the column for monomer a1 for convenience (the same applies to other examples).

<Method for measuring weight average molecular weight of copolymer>
The measurement of the weight average molecular weight of the copolymer was performed by size exclusion chromatography (GPC) under the following conditions.
[GPC conditions]
Standard substance: Polyethylene glycol equivalent (weight average molecular weight 875000, 540000, 235000, 145000, 107000, 24000)
Column: G4000PWXL + G2500PWXL (Tosoh)
Eluent: 0.2M phosphate buffer / acetonitrile = 9/1
Flow rate: 1.0 mL / min Column temperature: 40 ° C
Detector: RI

Example 1 and Comparative Example 1
(1) Mortar combination

The components in the table are as follows.
C: Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd./Sumitomo Osaka Cement Co., Ltd. = 50% by mass / 50% by mass) (density 3.16 g / cm ³ )
S: Fine aggregate, Joyosan sand (density 2.57 g / cm ³ )
W: Wakayama City tap water

(2) Manufacture of mortar Cement (C) and sand (S) with the formulation of Table 1 were stirred and mixed at low speed (about 60 rpm) for 10 seconds with a mortar mixer (KK-S, manufactured by Kansai Kikai Seisakusho Co., Ltd.) A mortar was prepared by adding water (W) to which a copolymer and an ester-based antifoaming agent (Formrex 797 manufactured by Nikka Chemical Co., Ltd.) were added, and stirring and mixing at low speed (about 60 rpm) for 1 to 2 minutes. . The production was carried out at 20 ° C.
The ester antifoaming agent was used to remove the influence of entrained air, and was added to water (W) so that the amount was 0.04 g per kg of mortar.
The copolymer was adjusted between 0.01% by mass and 1.0% by mass with respect to the amount of cement so that the mortar flow was 250 ± 10 mm. The mortar flow was measured according to JIS R 5201 (however, no falling motion was added).

(3) Mortar test Based on JIS A1132, the mortar was filled in a cylindrical plastic mold (bottom diameter: 5 cm, height 10 cm) by a two-layer packing method, and steam curing was performed. After curing for 1 hour at 20 ° C., the curing was immediately increased to 60 ° C. and held for 3 hours and 40 minutes, then removed from the curing tank and again placed at 20 ° C. for 1 hour. The maturity under this condition is 260 [° C. · hour].
Compressive strength was measured based on JIS A 1108 for the initial strength of the cured mortar that was demolded after steam curing.
Moreover, about the mortar before filling, as a viscosity evaluation, the flow-down time was measured by the J-type funnel test. The mortar immediately after kneading is fully filled in the J-type funnel test apparatus, and the time for the mortar to drop is measured.
The results are shown in Table 2.

A water / cement ratio of about 0.35 ± 0.05 is an area used for large products, and large products need to be lifted with a crane or the like at the time of demolding or after demolding. Therefore, the demoldable strength by this evaluation method is 15 N / mm ² or more. Examples 1-1 to 1-9 all reached 15 N / mm ² or more, which is a demoldable strength. Although Comparative Example 1-21 has reached the demoldable strength, the workability is inferior because the flow time is long and the viscosity is high.

Example 2 and Comparative Example 2
(1) Mixing of mortar It carried out similarly to Example 1.

(2) Production of mortar It was carried out in the same manner as in Example 1.

(3) Mortar test It carried out similarly to Example 1. However, the maturity was changed as shown in Table 3.
When the maturity was 260 [° C. / hour], the sample was left at 20 ° C for 1 hour, then immediately raised to 60 ° C and held for 3 hours and 40 minutes, then removed from the curing tank and again placed at 20 ° C for 1 hour (implementation) Same as Example 1).
When the maturity was 280 [° C./hour], the sample was preliminarily placed at 20 ° C. for 1 hour, immediately raised to 60 ° C. and held for 4 hours, then removed from the curing tank and again placed at 20 ° C. for 1 hour.
When the maturity was 300 [° C./hour], the sample was preliminarily placed at 20 ° C. for 1 hour, then immediately raised to 60 ° C. and held for 4 hours and 20 minutes, then removed from the curing tank and again placed at 20 ° C. for 1 hour.
Examples 2-1 to 2-3 are No. 1-1, Comparative Examples 2-1 to 2-3 were No. Examples 2-4 to 2-6 of No. 1-11 were No. 1-11. Comparative Examples 2-4 to 2-6 of No. 1-8 were No. 1-8. A 1-14 copolymer was used.
The results are shown in Table 3.

When the maturity was 260 to 300 [° C./hour], in Examples 2-1 to 2-6 using the copolymer belonging to the copolymer (A), all reached 15 N / mm ² or more, which was a demoldable strength. ing.

Example 3 and Comparative Example 3
(1) Mortar combination

  The components in the table are the same as in Example 1.

(2) Production of mortar It was carried out in the same manner as in Example 1.

(3) Mortar test It carried out similarly to Example 1. The copolymer is No. A 1-5 copolymer was used.
The results are shown in Table 5.

In Comparative Example 3-1, the compressive strength exceeds 20 N / mm ² and demolding is possible, but the flow time is too long and the workability is poor. From the results of Table 5, it can be seen that the effect of the copolymer (A) is remarkable for the hydraulic composition having a specific range of water / cement ratio.
Example 3-1 was tested at a water / cement ratio of 0.35 used for large products, and the demoldable strength by this evaluation method is 15 N / mm ² or more.
Example 3-2 was tested at a water / cement ratio of 0.45 used for small products, and the demoldable strength by this evaluation method is 8 N / mm ² or more.

Claims (3)

The manufacturing method of the hardening body of a hydraulic composition including following process (1)-(4).
Step (1) A component containing the copolymer (A), hydraulic powder, aggregate and water is kneaded so that the water / hydraulic powder ratio (mass ratio) is 0.35 or more and 0.45 or less. Preparing a hydraulic composition.
Process (2) The process of putting a hydraulic composition in a formwork.
Step (3) A step of curing the hydraulic powder in the mold with a curing time of 8 hours or less so that the accumulated temperature is 260 to 300 [° C./hour].
Step (4) A step of removing the cured body from the mold after curing.
<Copolymer (A)>
A monomer a1 represented by the following general formula (A1) and a monomer a2 represented by the following general formula (A2), a monomer a1 constituting the copolymer (A), A copolymer in which the molar ratio of reaction units of the monomer a2 is monomer a1 / monomer a2 = 60/40 or more and 90/10 or less.

(In the formula, M represents a hydrogen atom, alkali metal, alkaline earth metal (1/2 atom), ammonium, alkylammonium or substituted alkylammonium)

(Wherein R ¹ , R ² and R ³ are the same or different and represent a hydrogen atom or a methyl group, R ⁴ represents an alkyl group having 1 to 3 carbon atoms, and Y represents CH ₂ O, CH ₂ CH _{2 represents} O or COO, and n represents a number of 20 or more and 80 or less)   The method for producing a cured body of a hydraulic composition according to claim 1, wherein the copolymer (A) has a weight average molecular weight of 5,000 or more and 300,000 or less. The method for producing a cured body of a hydraulic composition according to claim 1 or 2, wherein R ³ in formula (A2) is hydrogen.