Method for manufacturing a void-added hardened body

Abstract

To provide a hydraulic cured body that can simultaneously achieve improved thermal insulation performance and weight reduction.SOLUTION: A method of producing a void-added hardened body includes the steps of: preparing a hydraulic slurry containing a hydraulic binder, additive water, and a water-absorbing polymer; and curing the hydraulic slurry, and drying and removing the additive water absorbed by the water-absorbing polymer, to form voids.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a void-added hardened body and a method for producing the same. [Background technology]

[0002] For example, hydraulic binders such as gypsum or mixtures of gypsum and cement react with water to form a porous hardened body.

[0003] Patent Document 1 describes a method for improving the fire resistance of a hardened hydraulic binder using a water-absorbing polymer. Specifically, the description mentions a method in which aggregate, in which water is sealed inside water-absorbing polymer granules and the outer shell is fixed with a specific binder, is placed inside a hardened body. According to this method, when the hardened body comes into contact with heat and flames, the water inside the outer shell exerts an endothermic effect, improving its fire resistance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2-51860 [Overview of the project] [Problems that the invention aims to solve]

[0005] While hardened bodies obtained by reacting a hydraulic binder with water are required to have improved thermal insulation performance and reduced weight depending on the application, the method described in Patent Document 1 cannot achieve both improved thermal insulation performance and reduced weight simultaneously. This invention provides a method for manufacturing a hydraulically hardened body that can simultaneously achieve improved thermal insulation performance and weight reduction. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] Prepare a hydraulic slurry containing a hydraulic binder, added water, and a water-absorbing polymer. A method for producing a void-added hardened body, comprising curing the hydraulic slurry and drying and removing the added water absorbed by the water-absorbing polymer to form voids. [2] The amount of added water shall be the sum of the amount of water used to harden the hydraulic binder and the amount of water equivalent to the voids. A method for producing a void-added cured body according to [1], wherein the amount of the water-absorbing polymer is an amount that absorbs the amount of water equivalent to the void. [3] The void-adding hardened body includes a void-adding hardened portion consisting of a base hardened portion in which the hydraulic binder has hardened and the void, When the design value for the volume ratio of the base hardened portion to the void-added hardened body is Vrb (unit: volume%), the design value for the volume ratio of the voids is Vra (unit: volume%), and the amount of hydraulic binder used is C (unit: kg), In advance, determine the water / binder ratio m (unit: times), which represents the mass ratio of the amount of curing water to the hydraulic binder, and the water absorption ratio n (unit: times), which is based on the mass of the water-absorbing polymer. A method for producing a void-added cured body of [2], wherein the amount of added water Wt (unit: kg) and the amount of water-absorbing polymer P (unit: kg) used in preparing the hydraulic slurry are designed by the following formulas (6a) to (6g). Wc = C·m …(6a) Vwc = Wc / ρw …(6b) Vc = C / ρc …(6c) Vwp = (Vwc + Vc) × Vra / Vrb …(6d) Wp = Vwp · ρw …(6e) P = Wp / n …(6f) Wt = Wc + Wp …(6g) [ρw represents the density of the added water (unit: kg / L), and ρc represents the density of the hydraulic binder (unit: kg / L).] [4] The density of the base hardened portion alone is determined in advance. ρb (unit: g / cm³) 3 ) seek, The density ρT (unit: g / cm³) of the void-added hardened portion to be obtained. 3According to [3], the volume ratio Vrb (unit: volume %) of the base cured part to the void-added cured body and the volume ratio Vra (unit: volume %) of the voids are designed by the following formulas (1) and (3). ρT = {(ρb × Vrb) + (ρa × Vra)} / VrT …(1) VrT = Vrb + Vra … (3) [In formula (1), ρa represents the density of air (unit: g / cm 3 ).] [5] First, obtain the thermal conductivity λb (unit: W / (m·K)) of only the base cured part in advance, According to the thermal conductivity λT (unit: W / (m·K)) of the void-added cured part to be obtained, the volume ratio Vrb (unit: volume %) of the base cured part to the void-added cured body and the volume ratio Vra (unit: volume %) of the voids are designed by the following formulas (2) and (3) according to [3]. λT = {(λb × Vrb) + (λa × Vra)} / VrT …(2) VrT = Vrb + Vra …(3) [In formula (2), λa represents the thermal conductivity of air (unit: W / (m·K)).] [6] A method for manufacturing a void-added cured body according to any one of [1] to [5], wherein the hydraulic binder and the water-absorbing polymer are mixed to prepare a preliminary mixture, and the added water is added to the preliminary mixture and kneaded to prepare the hydraulic slurry. [7] A method for manufacturing a void-added cured body according to any one of [1] to [6], wherein the hydraulic binder is gypsum or a mixture of gypsum and cement. [8] A void-added cured body including a base cured part in which the hydraulic binder has cured and voids formed by drying the water-absorbed water-absorbing polymer. [9] A void-added cured body according to [8], wherein the average value of the thermal conductivity measured by the hot wire method at each temperature of 25°C, 100°C, 200°C, 300°C, 400°C, 600°C, 800°C and 1000°C is 0.280 W / (m·K) or less.

Advantages of the Invention

[0007] According to the present invention, a void-added hardened body capable of simultaneously achieving improvement in the heat insulation performance and weight reduction of a hydraulic hardened body can be obtained.

Embodiments for Carrying out the Invention

[0008] [Hydraulic binder] The hydraulic binder used in this embodiment is a powder that reacts (hydration reaction) with water and hardens. For example, gypsum, cement, hydraulic lime, etc. may be mentioned. The hydraulic binder may be one type or a mixture of two or more types. In terms of excellent fire resistance, it is preferable to use gypsum or a mixture of gypsum and cement as the hydraulic binder. The cement is not particularly limited. For example, ordinary Portland cement, early strength Portland cement, ultra-early strength Portland cement, medium heat Portland cement, low heat Portland cement, sulfate-resistant Portland cement, low-alkali Portland cement, blended cement, blast furnace cement, fly ash cement, silica cement, eco-cement, etc. may be mentioned. The content of cement in the mixture of gypsum and cement is preferably more than 0 and 50% by mass or less, more preferably 2 - 50% by mass, and even more preferably 5 - 20% by mass. In this embodiment, the hydraulic binder reacts with the added water to form a base hardened part.

[0009] [Added water] The added water used in this embodiment may be any water that can undergo a hydration reaction with the hydraulic binder and harden the hydraulic binder. It may contain electrolytes. For example, tap water, well water, industrial water, desalted water, deionized water, seawater, etc. may be mentioned.

[0010] [Amount of water for hardening · water / binder ratio] In this specification, the amount of water for hardening means the amount of added water required for the hydraulic binder to harden and form a base hardened part. The "water / binder ratio" represents the mass ratio of the amount of water for hardening to the hydraulic binder. It is preferable to set an appropriate amount of curing water according to the desired hardness of the base cured portion, the flow value of the hydraulic slurry, etc. For example, the amount of curing water can be determined by conducting preliminary tests. Furthermore, if a standard value for the amount of mixing water is specified for commercially available hydraulic binders, the amount of curing water can be set using this standard value as a guideline. For example, the amount of curing water is preferably within ±10 volume%, and more preferably within ±5 volume%, of the standard value.

[0011] [Superabsorbent polymer] The water-absorbing polymer used in this embodiment can be any polymer that can be dispersed in a hydraulic slurry to absorb added water and can have the added water removed from the inside by drying. The shape of the superabsorbent polymer is not particularly limited. Granular shape is preferred. The average particle size is preferably 1 to 850 μm, more preferably 2 to 400 μm, even more preferably 5 to 150 μm, and particularly preferably greater than 5 μm and less than 50 μm. The water-absorbing polymer material can be any known material. Examples include polyacrylic acid (salt) resins, polysulfonic acid (salt) resins, maleic anhydride (salt) resins, polyacrylamide resins, polyvinyl alcohol resins, and polyethylene oxide resins. Examples of commercially available polyacrylic acid-based superabsorbent polymers include Nippon Shokubai Co., Ltd.'s products named "Aqualic CS" and "Aqualic CA." The water absorption ratio of a superabsorbent polymer can vary depending on the composition of the liquid being absorbed (type and concentration of electrolyte, pH, etc.). A superabsorbent polymer having a mass-based water absorption ratio n of 10 to 350 times in a hydraulic slurry is preferred. The water absorption ratio n is more preferably 15 to 100 times, and even more preferably 20 to 50 times. The mass-based water absorption ratio n in a hydraulic slurry is a value obtained by the following measurement method.

[0012] <Method for measuring the water absorption ratio n of superabsorbent polymers> The water absorption ratio n of the water-absorbing polymer in a hydraulic slurry containing a hydraulic binder, added water, and the water-absorbing polymer is determined by the following method. (1) In advance, determine the standard water absorption ratio h, which serves as a guideline for the water absorption ratio of the superabsorbent polymer, using the method described below. Specifically, a standard hydraulic binder solution is prepared by mixing the hydraulic binder to be measured with water. The water-absorbing polymer to be measured is then added to the resulting standard hydraulic binder solution and stirred for one minute to allow the polymer to absorb the water. The amount of water mixed with the hydraulic binder is set to be in the range of 35 to 55 parts by mass per 100 parts by mass of the hydraulic binder, and the amount of water-absorbing polymer added to the standard hydraulic binder water is set to be in the range of 1 to 3 parts by mass per 100 parts by mass of the standard hydraulic binder water, so that the water-absorbing polymer can absorb water sufficiently in the standard hydraulic binder water. After stirring is complete, suction filtration is performed to separate the water-absorbing polymer from the standard hydraulic binder water. The mass of the water-absorbing polymer (mass after water absorption) is measured, and the standard water absorption ratio h is determined using the following formula. Standard water absorption ratio h = (mass after water absorption - mass before water absorption) / mass before water absorption (2) Prepare a hydraulic slurry for measurement containing the hydraulic binder to be measured, added water, and a water-absorbing polymer, cure it, and dry it until it is completely dry to produce a void-added cured body for measurement. In this context, "perfectly dry" refers to the state where the material has reached "constant weight" as defined in JIS A 1476 "Method for Measuring the Moisture Content of Building Materials." Specifically, during the drying process, mass measurements are taken every 24 hours, and constant weight is determined to have been reached when the rate of mass change is 0.1% or less for three consecutive measurements. The mass of the hydraulic binder in the hydraulic slurry used for measurement can be set arbitrarily. The mass H of the water-absorbing polymer in the hydraulic slurry for measurement is set to an amount that allows the hydraulic slurry for measurement to cure without problems, within the range of 0.1 / 100 to 5 / 100 of the mass of the hydraulic binder. If the hydraulic slurry for measurement can cure without problems, a range of 0.5 / 100 to 3 / 100 is preferable, and a range of 1 / 100 to 2 / 100 is more preferable. The amount of water added to the hydraulic slurry for measurement shall be the sum of the amount of hardening water and the amount of water absorbed as described below. Curing water amount: The standard value of the mixing water amount for the hydraulic binder shall be used as the curing water amount. Amount of water absorbed: When the mass of the superabsorbent polymer is H and the standard water absorption ratio of the superabsorbent polymer determined in (1) above is h times (based on mass), the amount of water absorbed = (H × h). (3) Prepare a measurement base slurry by removing only the water-absorbing polymer from the measurement hydraulic slurry of (2) above, cure it, and dry it until it is completely dry to produce a measurement base cured body. (4) Let Q1 be the volume of the hardened body with added voids for measurement obtained in (2), Q2 be the volume of the hardened base body for measurement obtained in (3), and q be the density of the added water. The water absorption ratio n (based on mass) of the water-absorbing polymer is determined using the following formula. Note that the mass and volume of the water-absorbing polymer and the mass of air in the cured void-added body used for measurement can be ignored. Q1 = Q2 + A (where A is the volume of the void in Q1) n = (A × q) / H = {(Q1 - Q2) × q} / H

[0013] [Other materials] In this embodiment, in addition to the hydraulic binder, added water, and water-absorbing polymer, other materials may be used as needed. Other materials can be known materials. Examples include aggregates, organic fibers, inorganic fibers, etc.

[0014] <Method for manufacturing a void-added hardened product> The method for producing the void-added hardened body of this embodiment involves preparing a hydraulic slurry containing a hydraulic binder, added water, a water-absorbing polymer, and other materials as needed (slurry preparation step), hardening the obtained hydraulic slurry (hardening step), and drying and removing the added water absorbed by the water-absorbing polymer to form voids (drying step) to obtain the void-added hardened body.

[0015] [Slurry preparation process] In the slurry preparation process, all materials, including a hydraulic binder, added water, and a water-absorbing polymer, are kneaded to obtain a hydraulic slurry. A pre-mixing step may be included in which a hydraulic binder and a water-absorbing polymer are pre-mixed to prepare a preliminary mixture. Water is added to the obtained preliminary mixture and kneaded to prepare a hydraulic slurry. If other materials are used, the premixture may contain some or all of the other materials, and the remainder or all of the other materials may be added after the premixing step. Furthermore, a water absorption step may be included during the mixing process, in which the hydraulic slurry is allowed to stand to allow the water-absorbing polymer to absorb the added water. The duration of the water absorption step should preferably be set so that the water-absorbing polymer absorbs water sufficiently. For example, 5 to 30 minutes is preferred, and 20 to 30 minutes is more preferred.

[0016] [Curing process / drying process] In the curing process, the obtained hydraulic slurry is molded or coated according to the application, and then cured to harden. The drying process may involve actively drying the molded or coated hydraulic slurry by applying, for example, heat and / or air, or by natural drying, or a combination of these. Preferably, the drying is carried out until the void-added hardened body reaches an equilibrium drying state in the normal usage environment (room temperature environment), while ensuring that the crystalline water of the hardened body is not lost.

[0017] [Cavity-added hardened material] According to this embodiment, a void-added hardened body is obtained, which includes a base hardened portion formed by the hydration reaction of a hydraulic binder and voids formed by the drying and removal of added water within the water-absorbing polymer. The base cured portion may be porous. In this specification, "voids" do not include the micropores of the porous material. It is preferable that the voids are dispersed within the base cured portion. When the hydraulic slurry contains other materials, a void-added hardened body is obtained that includes the base hardened portion, the voids, and the other materials. The other materials may be dispersed within the base hardened portion.

[0018] By adding voids to the base hardened portion in this way, a void-added hardened body is obtained that is lighter than the base hardened portion and has improved thermal insulation performance. The larger the total volume of added voids (porosity), the lower the density of the hardened body with added voids, resulting in a lighter weight. The larger the total volume of added voids, the lower the thermal conductivity of the hardened material with added voids, and the better the insulation performance. In other words, the density and thermal conductivity of the hardened body with added voids can be controlled by the total volume of the added voids. For example, as shown in the examples described later, a void-added hardened body can be obtained in which the average value of the thermal conductivity measured by the hot-wire method is 0.280 W / (m·K) or less at each measurement temperature of 25°C, 100°C, 200°C, 300°C, 400°C, 600°C, 800°C, and 1000°C. The average value of the thermal conductivity is preferably 0.200 to 0.280 W / (m·K), and more preferably 0.220 to 0.260 W / (m·K).

[0019] The total volume of added voids can be controlled by the volume of the fraction (equivalent to the amount of water in the voids) of the added water used in preparing the hydraulic slurry that does not contribute to the hardening of the hydraulic binder and is removed by drying. The size of each individual void (void diameter) formed in the void-added hardened body can be controlled by the size and water absorption ratio of the water-absorbing polymer. The number of voids formed in the void-added hardened body can be controlled by the number of water-absorbing polymers. The average void diameter of the voids present in the void-added hardened body is preferably 10 to 40 μm, more preferably 15 to 30 μm, and even more preferably 20 to 25 μm. In this specification, the void diameter is the equivalent diameter of a circle in cross-section. The average void diameter is the most frequent particle diameter (mode diameter) in the number-based frequency distribution.

[0020] <Design method> In this embodiment, it is preferable to set the amount of added water used in preparing the hydraulic slurry to be the sum of the amount of water used to cure the hydraulic binder and the amount of water equivalent to the voids, and to design the amount of water-absorbing polymer to be the amount that absorbs the amount of water equivalent to the voids. For example, it is preferable to manufacture a void-added hardened body using the design method described below.

[0021] In the design method of this embodiment, the fraction of the void-added hardened body consisting only of the base hardened portion and voids is referred to as the "void-added hardened portion." Furthermore, the void-added cured body contains a water-absorbing polymer that has undergone a drying process, in addition to the base cured portion, voids, and other materials. As shown in the examples described later, the influence of the water-absorbing polymer on the density and thermal conductivity of the void-added cured body is negligibly small. Therefore, the density and thermal conductivity of the void-added cured body without other materials can be considered as the density and thermal conductivity of the void-added cured portion. In the following, the symbols shown in Table 1 may be used.

[0022] [Table 1]

[0023] [Calculation of density and thermal conductivity of void-added hardened material] The density ρT and thermal conductivity λT of the void-added hardened portion can be calculated using the following equations (1) to (3). The density of air ρa is calculated using the following formula (4), and the thermal conductivity of air λa is calculated using the following formula (5). ρT={(ρb×Vrb)+(ρa×Vra)} / VrT …(1) λT={(λb×Vrb)+(λa×Vra)} / VrT …(2) VrT = Vrb + Vra …(3) ρa = (351.99 / T + 333.84 / T) 2 ) × 10 -3 …(4) λa = (2.3340 × 10) -3 T 3 / 2 ) / (164.54+T) …(5) In the above equations (4) and (5), T represents absolute temperature (unit: Kelvin). For example, the average temperature of the environment in which the void-added hardened material is used can be adopted. In a room temperature environment, 20°C can typically be used.

[0024] [Design of volume ratios Vra and Vrb based on the density ρT of the void-added hardened zone] By first determining the density ρb of the base hardened portion only, the volume ratio Vrb of the base hardened portion and the volume ratio Vra of the voids can be designed according to the density ρT of the void-added hardened portion to be obtained, using the above equations (1) and (3).

[0025] [Gap addition hardened part Thermal conductivity Design of volume ratios Vra and Vrb based on λT] By first determining the thermal conductivity λb of the base hardened portion only, the volume ratio Vrb of the base hardened portion and the volume ratio Vra of the void can be designed according to the thermal conductivity λT of the void-added hardened portion to be obtained, using the above equations (2) and (3).

[0026] The Vra / Vrb value, which represents the ratio of the volume ratio of voids (Vra) to the volume ratio of the base hardened portion (Vrb), indicates that a larger value results in a greater reduction in density and thermal conductivity. On the other hand, if the Vra / Vrb value is too large, the strength of the void-added hardened portion may be insufficient. The Vra / Vrb value is preferably, for example, 0.05 to 4.0, more preferably 0.05 to 2.5, and even more preferably 0.05 to 1.0.

[0027] [Design of hydraulic slurry based on volume ratios Vra and Vrb] When manufacturing a void-added hardened body where the design values ​​for the volume ratio of the base hardened portion and the voids are Vrb and Vra, the amount of added water Wt and the amount of water-absorbing polymer P used in preparing the hydraulic slurry can be designed in the following way, depending on the amount of hydraulic binder C used. (i) Set the water / binder ratio m (unit: times) in advance. (ii) Determine the mass-based water absorption ratio n of the superabsorbent polymer in advance. (iii) The mass Wc and volume Vwc of the hardening water used to prepare the hydraulic slurry are determined by the following formulas (6a) and (6b). Wc = C·m …(6a) Vwc = Wc / ρw …(6b) (iv) The volume Vwp and mass Wp of the water equivalent to the void are determined using the following equations (6c) to (6e). Vc = C / ρc …(6c) Vwp = (Vwc + Vc) × Vra / Vrb …(6d) Wp = Vwp · ρw …(6e) (v) The amount P of water-absorbing polymer used in the preparation of the hydraulic slurry is determined by the following formula (6f). P = Wp / n …(6f) (vi) Determine the amount of water (Wt) used to prepare the hydraulic slurry using the following formula (6g). Wt = Wc + Wp …(6g) [Examples]

[0028] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. <Measurement method> The following measurement method was used. [Density of hydraulic binder ρc] The measurement was performed according to the method conforming to JIS A 6201 "For concrete" fly ash 8.4 density. [Cement content (equivalent to ordinary Portland cement)] The SiO2, Al2O3, and CaO content in hydraulic binders B and S were measured by X-ray fluorescence analysis. Based on the SiO2 content of 20.68 mass%, Al2O3 content of 5.28 mass%, and CaO content of 64.25 mass% (literature values) in ordinary Portland cement, the cement content X (unit: mass%) in hydraulic binder S was calculated using the following formula (I). X = (SB) / (NB) × 100 …(I) X: Cement content in hydraulic binder S (mass%) B: Content (mass%) of SiO2, Al2O3, and CaO in hydraulic binder B S: Content (mass%) of SiO2, Al2O3, and CaO in the hydraulic binder S N: Content of SiO2, Al2O3, and CaO in ordinary Portland cement (mass %)

[0029] [Thermal conductivity of the cured material] A cured body formed into a plate shape with a thickness of 20 mm was dried in an oven at 40 °C until it reached a completely dry state to obtain a sample. The weight change due to drying was measured every 24 hours, and it was determined that the completely dry state was reached when the mass change rate became 0.1% or less for three consecutive times. The thermal conductivity of the sample was measured by the hot wire method. The thermal conductivity measuring device used was the product name "ARC-TC-1000 type" manufactured by Agne. The measurement temperatures were 25 °C, 100 °C, 200 °C, 300 °C, 400 °C, 600 °C, 800 °C, and 1000 °C, and the average of the measured values at each temperature was obtained.

[0030] [Density of the cured body] A cured body formed into a cylindrical shape with a diameter of 50 mm and a height of 100 mm that was dried in an oven at 105 °C until it reached a completely dry state was used as a sample. The change in weight over time due to drying was measured every 24 hours, and it was determined that the completely dry state was reached when the mass change rate became 0.1% or less for three consecutive times. The mass of the sample was measured, and the density (absolute dry density) was determined by mass / volume.

[0031] The following materials were used. [Added water] For the added water, tap water (density ρw = 1 g / cm 3 ) was used. [Hydraulic binder] Hydraulic binder B: Gypsum, product name "B-YN Plaster" manufactured by Yoshino Gypsum Co., Ltd., density (measured value) 2.61 g / cm 3 , standard value of the mixing water amount: 11 - 13 L for 20 kg. Preliminary tests were conducted, and the water / binder ratio was set to 0.55 times, and the curing period after water addition was set to 3 days. Hydraulic binder S: A mixture of gypsum and cement, product name "SL Plaster" manufactured by Yoshino Gypsum Co., Ltd., density (measured value) 2.72 g / cm 3 , cement content (in terms of ordinary Portland cement, measured value) approximately 11 mass%, standard value of the mixing water amount: 8.75 L for 25 kg. Preliminary tests were conducted, and the water / binder ratio was set to 0.36 times, and the curing period after water addition was set to 2 days.

[0032] [Water-absorbing polymer] Superabsorbent polymer (P1): Modified acrylic crosslinked polymer, Nippon Shokubai Co., Ltd. product name "Aqualic CS-6S", average particle size (catalog value) 15 μm. The water absorption ratio n of the superabsorbent polymer (P1) was determined by the measurement method described above. When the hydraulic binder was hydraulic binder B, n was 25 times, and when the hydraulic binder was hydraulic binder S, n was 33 times.

[0033] [Reference example 1] In this example, a hardened body without voids (corresponding to only the base hardened portion) was manufactured using hydraulic binder B and added water for hardening. Specifically, hydraulic binder B was added to a mortar mixer, and water was added to achieve a water / binder ratio of 0.55. The mixture was then kneaded to prepare a hydraulic slurry. The mixing was carried out by kneading at low speed for 5 minutes, scraping off the excess, then kneading at high speed for 5 minutes, and finally discharging the mixture. The resulting hydraulic slurry was poured into a mold and cured for 3 days to obtain a hardened body. The density ρb and thermal conductivity λb of the obtained cured body (base cured portion) were measured using the method described above. The measurement results for density ρb are shown as measurement value x in Table 2, and the measurement results for thermal conductivity λb are shown as measurement value s in Table 3 (the same applies hereafter). Table 2 shows the results of designing a hydraulic slurry using the above formulas (6a) to (6g), with a usage amount C of hydraulic binder B being 10 kg.

[0034] [Example 1] In this example, a void-added cured body (corresponding to the void-added cured body) was manufactured by adding voids to the cured body (base cured body) of Reference Example 1 using a water-absorbing polymer (P1). The hydraulic slurry was designed using formulas (6a) to (6g) above, with a design value of 75 volume% for Vrb and 25 volume% for Vra. Table 2 shows the design values ​​of the hydraulic slurry when the amount C used for hydraulic binder B is 10 kg.

[0035] A hydraulic slurry was prepared based on the obtained design values. Specifically, a preliminary mixture was first prepared by mixing hydraulic binder B and water-absorbing polymer (P1). The preliminary mixture was placed in a mortar mixer, the total amount of added water was added, and the mixture was kneaded to prepare a hydraulic slurry. The kneading was carried out by mixing at low speed for 5 minutes, scraping, mixing at high speed for 5 minutes, stopping the mixing and letting it stand for 30 minutes (water absorption process), mixing again at low speed for 30 seconds, and then discharging. The obtained hydraulic slurry was molded and cured in the same manner as in Reference Example 1, and then dried until completely dry to form voids, thereby obtaining a void-added hardened body.

[0036] The density ρT and thermal conductivity λT of the obtained void-added hardened body (void-added hardened portion) were measured using the method described above. The measurement results for density ρT are shown as the measured value y in Table 2, and the measurement results for thermal conductivity λT are shown as the measured value t in Table 3 (the same applies hereafter). In Table 2, the ratio of the measured value y to the measured value x (y / x) is shown as the "reduction ratio" of density due to the addition of voids to the hardened base. Furthermore, the calculated value z is shown as the result of calculating the density ρT of the hardened part with added voids based on the above equation (1), and the ratio of the measured value y to the calculated value z (y / z) is shown as the "ratio to the calculated value." Note that the density ρa of air in the above equation (1) is the value calculated by the above equation (4) at a temperature of 20°C (ρa = 0.0012047) (the same applies hereafter). In Table 3, the ratio of the measured value t to the measured value s (t / s) is shown as the reduction ratio of thermal conductivity due to the addition of voids to the hardened base. Furthermore, the calculated value u is shown as the result of calculating the thermal conductivity λT of the hardened part with added voids based on equation (2) above, and the ratio of the measured value t to the calculated value u (t / u) is shown as the "ratio to the calculated value". Note that the thermal conductivity λa of air in equation (2) above is the value calculated by equation (5) above at a temperature of 20°C (λa shown in Table 5) (the same applies in Table 4 below).

[0037] [Reference example 2] In Reference Example 1, hydraulic binder B was replaced with hydraulic binder S, the water / binder ratio was set to 0.36, and the curing period after water addition was set to 2 days. Otherwise, the process was the same as in Reference Example 1 to produce a hardened body without added voids (corresponding only to the base hardened portion), and the density ρb and thermal conductivity λb were measured. Table 2 shows the results of designing a hydraulic slurry using the above formulas (6a) to (6g), with a hydraulic binder S amount C of 10 kg.

[0038] [Example 2] In this example, a void-added cured body (corresponding to the void-added cured body) was manufactured by adding voids to the cured body (base cured body) of Reference Example 2 using the same water-absorbing polymer (P1) as in Example 1. The hydraulic slurry was designed using formulas (6a) to (6g) above, with a design value of 70 volume% for Vrb and 30 volume% for Vra. Table 2 shows the design values ​​of the hydraulic slurry when the amount of hydraulic binder S used C is 10 kg.

[0039] Based on the obtained design values, a hydraulic slurry was prepared in the same manner as in Example 1. The obtained hydraulic slurry was molded and cured in the same manner as in Reference Example 2, and then dried until completely dry to form voids, thereby obtaining a void-added hardened body. The density ρT and thermal conductivity λT of the void-added hardened body (void-added hardened portion) were measured in the same manner as in Example 1. The results are shown in Tables 2 and 4.

[0040] [Table 2]

[0041] [Table 3]

[0042] [Table 4]

[0043] [Table 5]

[0044] As shown in the results in Table 2, the void-added cured body of Example 1, in which voids were added to the cured body of Reference Example 1, had a density reduction ratio (y / x) of 0.755. In other words, the weight was reduced by approximately 25% by adding voids to the base cured portion. Furthermore, the ratio to the calculated density (y / z) was 1.007. This means that the density was obtained almost as designed, and it was found that the effect of the presence of the water-absorbing polymer was negligibly small. Furthermore, as shown in the results in Table 3, the reduction ratio of thermal conductivity (t / s) was 0.813, indicating that the void-added cured body of Example 1 achieved an average reduction of approximately 20% in thermal conductivity compared to the cured body (base cured part) of Reference Example 1. The ratio of thermal conductivity to the calculated value (t / u) was 0.989 on average, although there was some variation depending on the measurement temperature. In other words, the thermal conductivity was obtained almost as designed, and the effect of the water-absorbing polymer was found to be negligibly small.

[0045] Similarly, as shown in the results in Table 2, the void-added cured body of Example 2, in which voids were added to the cured body of Reference Example 2, had a density reduction ratio (y / x) of 0.699. That is, the weight was reduced by approximately 30% by adding voids to the base cured portion. Furthermore, the ratio to the calculated density (y / z) was 0.998. In other words, the density was obtained almost as designed, and it was found that the effect of the presence of the water-absorbing polymer was negligibly small. Furthermore, as shown in the results in Table 4, the reduction ratio (t / s) of thermal conductivity was 0.718, and the void-added cured body of Example 2 was able to reduce the thermal conductivity by an average of approximately 28% compared to the cured body (base cured part) of Reference Example 2. In addition, the ratio of the thermal conductivity to the calculated value (t / u) was 0.966 on average, although there was some variation depending on the measurement temperature. In other words, the thermal conductivity was obtained almost as designed, and it was found that the effect of the presence of the water-absorbing polymer was negligibly small.

[0046] [Calculation of void diameter] Assuming that the particles of the superabsorbent polymer (P1) used in Examples 1 and 2 are perfectly spherical, the volume of the particles calculated from the average particle size of 15 μm is 1.767 × 10⁻⁶. -9 (Unit: cm) 3 It is a grain. Furthermore, since the water absorption ratio of the superabsorbent polymer (P1) in Examples 1 and 2 was large at 25 times and 33 times, respectively, the density of the superabsorbent polymer (P1) before and after water absorption should be the same as that of water, 1 g / cm³. 3 Assuming this, the mass of the particles before water absorption is 1.767 × 10⁻⁶ -9 (Unit: g / grain)

[0047] In Example 1, the mass of the superabsorbent polymer (P1) after absorbing water at a water absorption ratio of 25 times was 4.437 × 10⁻⁶. -8 (Unit: g / grain), volume is 4.437 × 10 -8 (Unit: cm) 3 The result is ( / particle), and the void diameter is calculated to be 0.00220 (unit: cm) = 22.0 (unit: μm). Furthermore, assuming a void ratio of 25 volume% in the void-added hardened body, 1 cm of void-added hardened body 3 The number of absorbent polymer particles (P1) per unit area after water absorption is 5,635,060 (unit: particles / cm²). 3 ) is calculated as follows.

[0048] Similarly, in Example 2, the mass of the superabsorbent polymer (P1) after absorbing water at a water absorption ratio of 33 times was 5.876 × 10⁻⁶. -8 (Unit: g / grain), volume is 5.876 × 10 -8 (Unit: cm) 3 The result is ( / particle), and the void diameter is calculated to be 0.00241 (unit: cm) = 24.1 (unit: μm). Furthermore, assuming a void ratio of 30 volume% in the void-added hardened body, 1 cm of void-added hardened body 3 The number of absorbent polymer particles (P1) per unit area after water absorption is 5,105,585 (unit: particles / cm²). 3 ) is calculated as follows.

Claims

1. A hydraulic slurry containing a hydraulic binder, added water, and a water-absorbing polymer is prepared. A method for producing a void-added cured body, comprising curing the hydraulic slurry, drying and removing the added water absorbed by the water-absorbing polymer to form voids, and including a void-added cured portion consisting of a base cured portion where the hydraulic binder has hardened and the voids, wherein the water-absorbing polymer is granular with an average particle diameter of more than 5 μm and less than 50 μm. Prior to this, the density ρb (unit: g / cm³) of the base hardened portion only should be determined. ３ ) and determine the density ρT (unit: g / cm³) of the void-added hardened portion to be obtained. ３ Depending on the following, the volume ratio Vrb (unit: volume%) of the base hardened portion to the void-added hardened body and the volume ratio Vra (unit: volume%) of the voids are designed using the following formulas (1) and (3): A method for manufacturing a void-added cured body, wherein the amount of added water is the sum of the amount of curing water for the hydraulic binder and the amount of water equivalent to the voids, the amount of the water-absorbing polymer is the amount that absorbs the amount of water equivalent to the voids, and the amount of the hydraulic binder used is C (unit: kg), the water / binder ratio m (unit: times), which represents the mass ratio of the amount of curing water to the hydraulic binder, and the mass-based water absorption ratio n (unit: times) of the water-absorbing polymer are determined in advance, the water absorption ratio n is determined by the method for measuring the water absorption ratio n below, and the amount of added water Wt (unit: kg) and the amount of water-absorbing polymer P (unit: kg) used in preparing the hydraulic slurry are designed using the following formulas (6a) to (6g). ρT={(ρb×Vrb)+(ρa×Vra)} / VrT…(1) VrT=Vrb+Vra... (3) [In equation (1), ρa is the density of air (unit: g / cm³) ３ ) represents. Wc=C・m...(6a) Vwc=Wc / ρw...(6b) Vc=C / ρc...(6c) Vwp=(Vwc+Vc)×Vra / Vrb...(6d) Wp=Vwp・ρw...(6e) P=Wp / n...(6f) Wt=Wc+Wp...(6g) [ρw represents the density of the added water (unit: kg / L), and ρc represents the density of the hydraulic binder (unit: kg / L).] <Method for measuring water absorption ratio n> (1) Prepare standard hydraulic binder water by mixing 100 parts by mass of the hydraulic binder to be measured with 35 to 55 parts by mass of water. Add 1 to 3 parts by mass of the water-absorbing polymer to be measured to the obtained standard hydraulic binder water, stir for 1 minute to allow the water-absorbing polymer to absorb the water, then filter by suction to separate the water-absorbing polymer from the standard hydraulic binder water. Measure the mass of the water-absorbing polymer after water absorption, and determine the standard water absorption ratio h using the following formula. Standard water absorption ratio h = (mass after water absorption - mass before water absorption) / mass before water absorption (2) Prepare a hydraulic slurry for measurement containing the hydraulic binder to be measured, added water, and a water-absorbing polymer, cure it, and dry it until it is completely dry to produce a void-added cured body for measurement. The mass H of the water-absorbing polymer in the hydraulic slurry for measurement shall be 0.1 / 100 to 5 / 100 of the mass of the hydraulic binder, and the amount of added water in the hydraulic slurry for measurement shall be the sum of the curing water amount and the water absorption water amount as shown below. Curing water amount: The standard value of the mixing water amount for the hydraulic binder shall be used as the curing water amount. Amount of water absorbed: When the mass of the superabsorbent polymer is H and the standard water absorption ratio of the superabsorbent polymer determined in (1) above is h times (based on mass), the amount of water absorbed = (H × h). (3) Prepare a base slurry for measurement by removing only the water-absorbing polymer from the hydraulic slurry for measurement described in (2) above, cure it, and dry it until it is completely dry to produce a cured base body for measurement. (4) Let Q1 be the volume of the void-added hardened body for measurement obtained in (2), Q2 be the volume of the base hardened body for measurement obtained in (3), and q be the density of the added water. Then, the water absorption ratio n (by mass) of the superabsorbent polymer is determined by the following formula. Q1 = Q2 + A (where A is the volume of the void in Q1) n=(A×q) / H={(Q1-Q2)×q} / H

2. A hydraulic slurry containing a hydraulic binder, added water, and a water-absorbing polymer is prepared. A method for producing a void-added cured body, comprising curing the hydraulic slurry, drying and removing the added water absorbed by the water-absorbing polymer to form voids, and including a void-added cured portion consisting of a base cured portion where the hydraulic binder has hardened and the voids, wherein the water-absorbing polymer is granular with an average particle diameter of more than 5 μm and less than 50 μm. In advance, the thermal conductivity λb (unit: W / (m·K)) of the base hardened portion alone is determined, and according to the thermal conductivity λT (unit: W / (m·K)) of the void-added hardened portion to be obtained, the volume ratio Vrb (unit: volume%) of the base hardened portion and the volume ratio Vra (unit: volume%) of the voids to the void-added hardened body are designed using the following formulas (2) and (3). A method for manufacturing a void-added cured body, wherein the amount of added water is the sum of the amount of curing water for the hydraulic binder and the amount of water equivalent to the voids, the amount of the water-absorbing polymer is the amount that absorbs the amount of water equivalent to the voids, and the amount of the hydraulic binder used is C (unit: kg), the water / binder ratio m (unit: times), which represents the mass ratio of the amount of curing water to the hydraulic binder, and the mass-based water absorption ratio n (unit: times) of the water-absorbing polymer are determined in advance, the water absorption ratio n is determined by the method for measuring the water absorption ratio n below, and the amount of added water Wt (unit: kg) and the amount of water-absorbing polymer P (unit: kg) used in preparing the hydraulic slurry are designed using the following formulas (6a) to (6g). λT={(λb×Vrb)+(λa×Vra)} / VrT…(2) VrT=Vrb+Vra...(3) [In equation (2), λa represents the thermal conductivity of air (unit: W / (m·K)).] Wc=C・m...(6a) Vwc=Wc / ρw...(6b) Vc=C / ρc...(6c) Vwp=(Vwc+Vc)×Vra / Vrb...(6d) Wp=Vwp・ρw...(6e) P=Wp / n...(6f) Wt=Wc+Wp...(6g) [ρw represents the density of the added water (unit: kg / L), and ρc represents the density of the hydraulic binder (unit: kg / L).] <Method for measuring water absorption ratio n> (1) Prepare standard hydraulic binder water by mixing 100 parts by mass of the hydraulic binder to be measured with 35 to 55 parts by mass of water. Add 1 to 3 parts by mass of the water-absorbing polymer to be measured to the obtained standard hydraulic binder water, stir for 1 minute to allow the water-absorbing polymer to absorb the water, then filter by suction to separate the water-absorbing polymer from the standard hydraulic binder water. Measure the mass of the water-absorbing polymer after water absorption, and determine the standard water absorption ratio h using the following formula. Standard water absorption ratio h = (mass after water absorption - mass before water absorption) / mass before water absorption (2) Prepare a hydraulic slurry for measurement containing the hydraulic binder to be measured, added water, and a water-absorbing polymer, cure it, and dry it until it is completely dry to produce a void-added cured body for measurement. The mass H of the water-absorbing polymer in the hydraulic slurry for measurement shall be 0.1 / 100 to 5 / 100 of the mass of the hydraulic binder, and the amount of added water in the hydraulic slurry for measurement shall be the sum of the curing water amount and the water absorption water amount as shown below. Curing water amount: The standard value of the mixing water amount for the hydraulic binder shall be used as the curing water amount. Amount of water absorbed: When the mass of the superabsorbent polymer is H and the standard water absorption ratio of the superabsorbent polymer determined in (1) above is h times (based on mass), the amount of water absorbed = (H × h). (3) Prepare a base slurry for measurement by removing only the water-absorbing polymer from the hydraulic slurry for measurement described in (2) above, cure it, and dry it until it is completely dry to produce a cured base body for measurement. (4) Let Q1 be the volume of the void-added hardened body for measurement obtained in (2), Q2 be the volume of the base hardened body for measurement obtained in (3), and q be the density of the added water. Then, the water absorption ratio n (by mass) of the superabsorbent polymer is determined by the following formula. Q1 = Q2 + A (where A is the volume of the void in Q1) n=(A×q) / H={(Q1-Q2)×q} / H

3. A method for producing a void-added hardened body according to claim 1 or 2, comprising: mixing the hydraulic binder and the water-absorbing polymer to prepare a premixture; adding the added water to the premixture and kneading to prepare the hydraulic slurry.

4. A method for producing a void-adding hardened body according to any one of claims 1 to 3, wherein the hydraulic binder is gypsum or a mixture of gypsum and cement.

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