Manufacturing method of self-leveling material

Abstract

To provide a manufacturing method of a self-leveling material, in manufacturing the self-leveling material in a ready mixed concrete factory, having a pot life long enough even under a high temperature environment and causing no decrease in compression strength due to an increase of a water-cement ratio.SOLUTION: A manufacturing method of a self-leveling material includes: a first kneading step of kneading powders including cement and fine aggregate to prepare a powder composition; a second kneading step of, after the first kneading step, adding 4-25 pts.mass of water relative to 100 pts.mass of the powder composition and kneading the mix; and a third kneading step of, after the second kneading step, adding a water-reducing agent and 3-20 pts.mass of water relative to 100 pts.mass of the powder composition and kneading the mix.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a self-leveling material. [Background technology]

[0002] Cement-based self-leveling materials (SL materials) are slurry-like mixtures made by adding water to a mixture of cement and fine aggregate as the base material and various admixtures. SL materials utilize the high fluidity inherent to the slurry to form smooth floor surfaces.

[0003] There are several methods for manufacturing SL material, including high-speed agitation of mortar materials and water in a dedicated plant, or dry mixing of mortar materials in a ready-mix mixer, followed by adding a specified amount of water for the primary mixing (stiff kneading), and then adding a further specified amount of water for the secondary mixing (main kneading).SL material manufactured using these methods is also called raw SL material, and is transported from the plant to the construction site in an agitator truck.

[0004] Patent Document 1 describes a method for mixing a self-leveling material, which is characterized by adding a part of the mixing water and mortar material to a mixer for ready-mixed concrete, stirring and mixing them, and then adding the remaining mixing water and mixing them. 2+ , Fe 3+ and Ni 2+ The present invention describes a method for producing a self-leveling material using a setting initiator for a cement-based self-leveling material, which comprises a substance that supplies metal ions selected from the group consisting of nitrate ions and nitrate ions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-320527 [Patent Document 2] Japanese Patent Application Publication No. 9-156976 Summary of the Invention [Problem to be solved by the invention]

[0006] However, raw SL lumber has the problem that in high-temperature environments such as summer, where temperatures reach 30°C or higher, the fluidity decreases during transportation due to the progress of the cement hydration reaction, and the usable life by the end of construction cannot be secured sufficiently. In order to secure the usable life of raw SL lumber, measures have been taken, such as adding high-performance water-reducing agents or increasing the amount of water, or manufacturing it in a dedicated plant with high-speed mixing. However, these measures have had issues such as a decrease in compressive strength due to an increase in the water-cement ratio, an increase in unit price, and the need for large capital investment.

[0007] Therefore, the present invention aims to provide a method for producing a self-leveling material in a ready-mix concrete factory, which has a sufficient usable life even in a high-temperature environment and does not cause a decrease in compressive strength due to an increase in the water-cement ratio. [Means for solving the problem]

[0008] As a result of thorough research into the above-mentioned problems, the inventors have discovered that by adjusting the amount of water in each mixing step and the timing of adding the water-reducing agent, it is possible to produce a self-leveling material that has sufficient usable life even in high-temperature environments and does not cause a decrease in compressive strength due to an increase in the water-cement ratio.

[0009] That is, the present invention is as follows. [1] A method for producing a self-leveling material, comprising: a first kneading step of kneading powder containing cement and fine aggregate to prepare a powder composition; a second kneading step of adding 4 to 25 parts by mass of water to 100 parts by mass of the powder composition after the first kneading step, and kneading the resulting mixture; and a third kneading step of adding a water-reducing agent and 3 to 20 parts by mass of water to 100 parts by mass of the powder composition after the second kneading step, and kneading the resulting mixture. [2] The manufacturing method according to [1], wherein the powder composition contains a pozzolanic substance and gypsum. [3] The manufacturing method according to [1] or [2], wherein the water-reducing agent is a polycarboxylic acid-based water-reducing agent. [4] The manufacturing method according to any one of [1] to [3], wherein the total amount of water added in the second kneading step and the third kneading step is 15 to 30 parts by mass per 100 parts by mass of the powder composition. [5] The manufacturing method according to any one of [1] to [4], wherein the amount of the water reducing agent added is 0.01 to 1.5 parts by mass in terms of solid content per 100 parts by mass of the powder composition. [6] The manufacturing method according to any one of [1] to [5], wherein the mass ratio of the water added in the second kneading step to the water added in the third kneading step ([mass of water added in the second kneading step] / [mass of water added in the third kneading step]) is 0.3 to 5. [Effects of the Invention]

[0010] According to the present invention, a method for producing a self-leveling material in a ready-mixed concrete factory can be provided that has a sufficient usable life even in a high-temperature environment and does not cause a decrease in compressive strength due to an increase in the water-cement ratio. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, the amounts added are all calculated on a solid basis and on an anhydrous basis.

[0012] The method for producing a self-leveling material of this embodiment includes a first kneading step in which powder containing cement and fine aggregate is kneaded to prepare a powder composition; a second kneading step in which, after the first kneading step, 4 to 25 parts by mass of water is added to 100 parts by mass of the powder composition and kneaded; and a third kneading step in which, after the second kneading step, a water reducing agent and 3 to 20 parts by mass of water are added to 100 parts by mass of the powder composition and kneaded.

[0013] In the first mixing step, powder containing cement and fine aggregate is mixed to prepare a powder composition. A mixer for ready-mixed concrete is usually used for mixing, but if the capacity is small, commonly used mixing equipment such as a tilting mixer, a twin-shaft mixer, or a Hobart mixer can also be used. The first to third mixing steps can be performed in a single sequence using the same mixing equipment. The kneading time is not particularly limited as long as the raw materials can be mixed and kneaded sufficiently to the extent that no lumps are formed, and can be adjusted appropriately depending on the production amount and the equipment used. The kneading time can be, for example, 1 to 1.5 minutes.

[0014] Various cements can be used, including, for example, various Portland cements such as normal, early strength, ultra-early strength, low heat and medium heat, ecocement, rapid hardening cement, fly ash cement, etc. One type of cement may be used alone, or two or more types may be used in combination.

[0015] The amount of cement added is preferably 20 to 45 parts by mass, more preferably 25 to 40 parts by mass, and even more preferably 30 to 38 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of cement added is within the above range, it is easy to ensure sufficient fluidity and various strengths as a self-leveling material.

[0016] Examples of fine aggregates include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. It is preferable to use silica sand, limestone, or other fine aggregates adjusted to a particle size that does not contain fine powder or coarse aggregate. One type of fine aggregate may be used alone, or two or more types may be used in combination. It is preferable to use fine aggregates with a particle size of 1.2 mm or less (passing through a 1.2 mm sieve), which are commonly used.

[0017] The particle size of the fine aggregate is not particularly limited and can be adjusted within the required particle size range. The particle size of the fine aggregate can be determined based on the coarse particle ratio specified in JIS A 1102:2014 "Sieving Test Method for Aggregates." From the viewpoint of achieving better fluidity and suppressing bleeding, the coarse particle ratio of the fine aggregate is preferably 1 to 3, more preferably 1.5 to 2.8, and even more preferably 1.8 to 2.4.

[0018] The amount of fine aggregate added is preferably 35 to 70 parts by mass, more preferably 40 to 65 parts by mass, and even more preferably 45 to 60 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of fine aggregate added is within the above range, it is easy to ensure sufficient fluidity and compressive strength as a self-leveling material.

[0019] The powder composition may contain a pozzolanic substance. Examples of pozzolanic substances include fly ash, silica fume, ground slag, volcanic ash, acid clay, activated clay, aluminosilicate clay minerals such as kaolin minerals, and their calcined products, with fly ash being preferred. One type of pozzolanic substance may be used alone, or two or more types may be used in combination. From the viewpoint of achieving even better fluidity, the fineness of the pozzolanic substance is 1500 to 8000 cm in terms of Blaine specific surface area. 2 / g is preferred, and 2000 to 6000 cm 2 / g is more preferred.

[0020] The amount of the pozzolanic substance added is preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass, and even more preferably 5 to 12 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of the pozzolanic substance added is within the above range, it is easy to ensure sufficient fluidity as a self-leveling material.

[0021] The powder composition may contain gypsum. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. As the gypsum, anhydrous gypsum is preferred from the viewpoint of further improving strength development. One type of gypsum may be used alone, or two or more types may be used in combination.

[0022] The amount of gypsum added is preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, and even more preferably 3 to 8 parts by mass, relative to 100 parts by mass of the powder composition. When the amount of gypsum added is within the above range, it is likely to be effective in suppressing excessive expansion and contraction.

[0023] The powder composition may contain a thickener. The type of thickener is not particularly limited, and examples thereof include cellulose-based thickeners, acrylic thickeners, and guar gum thickeners. Cellulose-based thickeners are preferred as thickeners. Examples of cellulose-based thickeners include carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. One type of thickener may be used alone, or two or more types may be used in combination.

[0024] The amount of thickener added is preferably 0.01 to 1 part by mass, more preferably 0.03 to 0.8 parts by mass, and even more preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of the powder composition. If the amount of thickener added is within the above range, it is easy to exhibit an appropriate effect of suppressing aggregate separation.

[0025] The powder composition may contain an antifoaming agent. The antifoaming agent is not particularly limited as long as it is an antifoaming agent used in general concrete, and examples thereof include mineral oil-based antifoaming agents, ester-based antifoaming agents, amine-based antifoaming agents, amide-based antifoaming agents, polyether-based antifoaming agents, and silicone-based antifoaming agents.

[0026] The amount of the antifoaming agent added is preferably 0.01 to 1 part by mass, more preferably 0.03 to 0.8 parts by mass, and even more preferably 0.05 to 0.5 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of the antifoaming agent added is within the above range, it is likely to be effective in defoaming the mixing air.

[0027] The powder composition according to this embodiment may contain various additives (materials) within the range that does not impair the effects of the present invention. Examples of additives (materials) include expanding agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, thickeners, water retention agents, pigments, water repellents, and anti-efflorescence agents.

[0028] In the second kneading step, water is added to the powder composition prepared in the first kneading step and kneaded. The kneading time is not particularly limited as long as the powder composition and water are uniformly kneaded, and can be appropriately adjusted depending on the production amount and the equipment used. The kneading time can be, for example, 2.5 to 3.5 minutes.

[0029] The amount of water added in the second kneading step is 4 to 25 parts by mass, preferably 8 to 20 parts by mass, and more preferably 12 to 18 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of water added in the second kneading step is within the above range, there will be few kneaded lumps, and it will be easy to prepare a good self-leveling material.

[0030] In the third kneading step, a water-reducing agent and water are further added to the powder composition kneaded with water in the second kneading step, and the mixture is kneaded. The kneading time is not particularly limited as long as the various materials being kneaded are uniform, and can be adjusted appropriately depending on the production amount and the equipment used. The kneading time can be, for example, 2.5 to 3.5 minutes. Adding a water-reducing agent in the third kneading step makes it possible to maintain fluidity for a long period of time, even in a high-temperature environment. As a result, the method for producing a self-leveling material of this embodiment can produce a self-leveling material that has a sufficient usable life and does not cause a decrease in compressive strength due to an increase in the water-cement ratio.

[0031] Water-reducing agents include high-performance water-reducing agents, high-performance air-entraining water-reducing agents, air-entraining water-reducing agents, and superplasticizers. Examples of such water-reducing agents include those specified in JIS A 6204:2011 "Chemical admixtures for concrete." Examples of water-reducing agents include polycarboxylic acid-based water-reducing agents, naphthalene sulfonic acid-based water-reducing agents, lignin sulfonic acid-based water-reducing agents, and melamine-based water-reducing agents. Among these, polycarboxylic acid-based water-reducing agents are preferred. One type of water-reducing agent may be used alone, or two or more types may be used in combination.

[0032] The amount of the water reducing agent added is preferably 0.01 to 1.5 parts by mass, more preferably 0.03 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass, based on 100 parts by mass of the powder composition in terms of solid content. If the amount of the water reducing agent added is within the above range, the self-leveling material will exhibit sufficient fluidity and will be able to easily maintain its usable life.

[0033] The amount of water added in the third kneading step is 3 to 20 parts by mass, preferably 4 to 15 parts by mass, and more preferably 6 to 10 parts by mass, relative to 100 parts by mass of the powder composition. If the amount of water added in the third kneading step is within the above range, the self-leveling material will have sufficient fluidity.

[0034] The total amount of water added in the second kneading step and the third kneading step is preferably 15 to 30 parts by mass, more preferably 17 to 28 parts by mass, and even more preferably 20 to 25 parts by mass, relative to 100 parts by mass of the powder composition.

[0035] The mass ratio of water added in the second kneading step to water added in the third kneading step ([mass of water added in the second kneading step] / [mass of water added in the third kneading step]) is preferably 0.3 to 5, more preferably 1 to 3, and even more preferably 1.5 to 2. If the mass ratio of water is within the above range, the composition will have even better stability with little change in performance.

[0036] According to the method for producing a self-leveling material of this embodiment, it is possible to obtain a self-leveling material that has sufficient usable time even in a high-temperature environment when prepared in a ready-mixed concrete factory and that does not cause a decrease in compressive strength due to an increase in the water-cement ratio. Therefore, this production method allows for sufficient time for transportation and construction even in a high-temperature environment such as summer. [Example]

[0037] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0038] [material] Ordinary Portland cement Fly ash: Blaine specific surface area 3600cm 2 / g Gypsum: anhydrous gypsum, specific surface area 3900 cm 2 / g Thickener: Methylcellulose-based thickener Defoamer: Polyether-based defoamer Fine aggregate River sand: coarse grain ratio 2.20 Silica sand: coarse grain ratio 2.05 Limestone sand: coarse grain ratio 2.11 Water reducing agent: Polycarboxylic acid water reducing agent

[0039] [Self-leveling material manufacturing method] A total of 2 kg of powder composition (cement, fly ash, gypsum, thickener, antifoaming agent, fine aggregate) was mixed and kneaded for 30 seconds in a Hobart mixer (first mixing). Water was added to the mixed powder composition and kneaded for 2.5 minutes (second mixing). After the second mixing, more water was added and kneaded for 2.5 minutes (third mixing) to prepare a self-leveling material. The water-reducing agent was added together with water during the second or third mixing. Each operation was carried out in a 30°C environment (constant temperature room). The mixing ratios of various materials, the amount and ratio of water added during the second and third mixing, and the timing of adding the water-reducing agent are shown in Table 1. All of the mixing ratios shown in Table 1 are values ​​calculated on an anhydrous basis and solid content basis.

[0040] [Evaluation method] The various evaluation tests were carried out in an environment of 30°C. The results of the various evaluations are shown in Table 1. Flow testing The flow value was measured in accordance with JASS-15M-103 (quality standard for self-leveling materials) of the Architectural Institute of Japan. Measurements were taken 0, 2, 4, and 6 hours after the end of the third mixing. ·Flow time The flow time is determined by the Japan Society of Civil Engineers standard. 14 Refer to the funnel tester to see the degree of viscosity more clearly. 10 Measurement was carried out using a funnel tester at 0, 2, 4 and 6 hours after the end of the third kneading. Compression strength The compressive strength of 14-day-old specimens was measured in accordance with JIS R5201:2015 "Physical Testing Methods for Cement." The hardened specimens were demolded 24 hours after molding and cured in air in a constant temperature room at 30°C until the specimens were 14 days old.

[0041] [Table 1]

[0042] The self-leveling materials of the examples had fluidity that did not interfere with work even after 6 hours had passed after the completion of the three-step kneading in a 30°C environment, so that the usable time could be secured and the compressive strength development after hardening was also good. In particular, the self-leveling materials of Examples 1 to 4 not only did not decrease in flow value, but also had a fast flow time, making them particularly easy to work with. On the other hand, the self-leveling materials of the comparative examples were prone to a decrease in fluidity, making it difficult to secure the usable time, or attempting to secure the usable time resulted in a relative decrease in compressive strength.

Claims

1. a first kneading step of kneading powders including cement, a pozzolanic substance, gypsum, and fine aggregate to prepare a powder composition; A method for producing a self-leveling material, comprising: a second kneading step of adding 4 to 25 parts by mass of water to 100 parts by mass of the powder composition and kneading the mixture after the first kneading step; and a third kneading step of adding a water reducing agent and 3 to 20 parts by mass of water to 100 parts by mass of the powder composition and kneading the mixture after the second kneading step.

2. The manufacturing method according to claim 1 , wherein the water-reducing agent is a polycarboxylic acid-based water-reducing agent.

3. 3. The method according to claim 1, wherein a total amount of water added in the second kneading step and the third kneading step is 15 to 30 parts by mass relative to 100 parts by mass of the powder composition.

4. The manufacturing method according to any one of claims 1 to 3, wherein the amount of the water reducing agent added is 0.01 to 1.5 parts by mass in terms of solid content per 100 parts by mass of the powder composition.

5. The mass ratio of the water added in the second kneading step to the water added in the third kneading step ([mass of water added in the second kneading step] / [mass of water added in the third kneading step]) is 0.3 to 5. The production method according to any one of claims 1 to 4.

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