Mortar composition and mortar

Abstract

To provide a mortar composition and a mortar which have sufficient pot life and exhibit favorable strength development over a long period.SOLUTION: A mortar composition according to the present invention comprises (A) cement, (B) gypsum materials, (C) pozzolanic substances, (D) hydroxycarboxylic acid-based set retarders, and (E) fine aggregate. The content of the component (B) is 16 to 49 pts.mass relative to 100 pts.mass of the component (A). The mass ratio (b / c) of the component (B) to the component (C) is 0.2 to 3.25. A mortar according to the present invention comprises the mortar composition in combination with water.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a mortar composition and a mortar.

Background Art

[0002] When cementitious materials are used in the repair and reinforcement of concrete structures, in recent years, under the high-temperature environment in summer, not only rapid-hardening materials but also hardening is accelerated, making it difficult to control the workable time. To ensure the workable time of cementitious materials, there are methods such as adding water or adding a setting retarder to delay the hardening rate.

[0003] As a method for ensuring the workable time of cementitious materials, for example, Patent Document 1 discloses a method for retarding the setting of cement, characterized in that cement concrete or cement mortar containing 0.01 to 3 parts by weight of a hydrolyzable tannin compound with respect to 100 parts by weight of cement is heated to 30°C to 100°C during and / or after kneading. Patent Document 2 discloses a method for controlling the setting time of concrete, in which a setting retarder is added to concrete or mortar not containing an activator and kneaded, and an activator is added immediately before placing the concrete or mortar to control the setting time of the concrete or mortar.

Prior Art Documents

[0004]

Patent Documents

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​However, in the conventional methods for ensuring the workable time, there was a risk of affecting the long-term strength development and not being able to satisfy the predetermined performance. In recent years, from the perspective of the maintenance and management of concrete structures, the long life of the structures has been achieved by improving the durability. Therefore, high strength development is required for the mortar and concrete used for the repair and reinforcement of concrete structures.

[0006] Therefore, there has been a demand for a mortar composition and mortar having a sufficient workable time and good strength development over a long period.

Means for Solving the Problems

[0007] As a result of the present inventor's intensive study on the above problems, it has been found that when gypsum and pozzolanic substances are in specific blending ratios and further combined with a specific setting retarder, a mortar composition and mortar with excellent workable time and high strength development can be obtained.

[0008] That is, the present invention is as follows [1] to [6]. [1] (A) Cement, (B) Gypsum, (C) Pozzolanic substance, (D) Hydroxycarboxylic acid-based setting retarder, and (E) Fine aggregate, and The content of component (B) is 16 to 49 parts by mass with respect to 100 parts by mass of component (A), The mortar composition in which the mass ratio (b / c) of component (B) to component (C) is 0.2 to 3.25. [2] The mortar composition according to [1], further comprising (F) an expansive agent. [3] The mortar composition according to [1] or [2], wherein the total content (b + c) of components (B) and (C) is 17 to 74 parts by mass with respect to 100 parts by mass of component (A). [4] Comprising any one of the mortar compositions of [1] to [3] and water, Mortar in which the water content is 35 to 55 parts by mass with respect to 100 parts by mass of the cement. [5] At the time of hardening, the compressive strength at 1 day of age measured in an environment of 20 ° C in accordance with JIS A 1108:2018 "Test method for compressive strength of concrete" is 10 N / mm 2 or less, and the compressive strength at 28 days of age is 58 N / mm 2 or more, the mortar according to [4]. [6] The mortar according to [4] or [5], wherein the 15-beat flow value of the mortar measured in an environment of 20 ° C in accordance with JIS R 5201:2015 "Physical test method for cement" is 140 to 200 mm.

Effect of the Invention

[0009] According to the present invention, it is possible to provide a mortar composition and mortar having a sufficient pot life and good long-term strength development property.

Mode for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail. Regarding the description of the content in this specification, it is in terms of solid content conversion and anhydride conversion, and the moisture contained in a liquid, if any, is included in the water content.

[0011] The mortar composition of this embodiment contains (A) cement, (B) gypsum, (C) pozzolanic substance, (D) hydroxycarboxylic acid-based setting retarder, and (E) fine aggregate.

[0012] (A) Various cements can be used, for example, various Portland cements such as ordinary, early strength, ultra-early strength, low heat and medium heat, eco-cement, fly ash cement, etc. are mentioned. As the cement, ordinary Portland cement and early strength Portland cement are preferable. The cement may be used alone or in combination of two or more.

[0013] The content of cement (a) is preferably 10 to 55 parts by mass, more preferably 12 to 45 parts by mass, and even more preferably 15 to 40 parts by mass with respect to 100 parts by mass of the mortar composition. When the content of cement is within the above range, better strength development can be obtained.

[0014] (B) Examples of the gypsum materials include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. From the viewpoint of further improving the strength development property, anhydrous gypsum is preferred as the gypsum material. The gypsum materials may be used alone or in combination of two or more. From the viewpoint of further enhancing the long-term strength development property, the fineness of the gypsum materials is preferably 3000 cm 2 / g or more in terms of the Blaine specific surface area, and more preferably 5000 cm 2 / g or more. The fineness of the gypsum materials is preferably 15000 cm 2 / g or less in terms of the Blaine specific surface area.

[0015] The content of the gypsum materials (b) is 16 to 49 parts by mass in terms of anhydride with respect to 100 parts by mass of cement. If the content of the gypsum materials is outside the above range, mixing becomes difficult and sufficient strength development property over a long period cannot be obtained. From the viewpoint of facilitating the mixing of the mortar and further improving the long-term strength development property, the content of the gypsum materials is preferably 17 to 40 parts by mass, more preferably 18 to 30 parts by mass, and even more preferably 18.5 to 25 parts by mass.

[0016] (C) Examples of the pozzolanic materials include fly ash, silica fume, blast furnace slag fine powder, volcanic ash, acid clay and activated clay, and amorphous aluminosilicates such as metakaolin. The pozzolan fine powder may be used alone or in combination of two or more. The fineness of the pozzolanic materials is preferably selected so that the long-term strength development property is further improved. Specifically, when fly ash, blast furnace slag, etc. are used as the pozzolanic materials, the Blaine specific surface area is preferably 3000 to 25000 cm 2 / g, and preferably 4000 to 22000 cm 2It is more preferably / g, and even more preferably 6000 to 20000 cm 2 / g. When silica fume, amorphous aluminosilicate, etc. are used as the pozzolanic substance, its BET specific surface area is preferably 5 to 30 m 2 / g, more preferably 7 to 25 m 2 / g, and even more preferably 8 to 22 m 2 / g.

[0017] The content (c) of the pozzolanic substance is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass, even more preferably 7 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass with respect to 100 parts by mass of cement. If the content of the pozzolanic substance is within the above range, the long-term strength development property will be further improved.

[0018] In the mortar composition of this embodiment, the mass ratio (b / c) of (B) gypsum and (C) pozzolanic substance is 0.2 to 3.25. If the mass ratio of gypsum and pozzolanic substance is outside the above range, the balance of the powder components may be poor and it may be difficult to mix, or the long-term strength development property may not be excellent. From the viewpoint of making it easier to mix the mortar and further improving the long-term strength development property, the mass ratio (b / c) of gypsum and pozzolanic substance is preferably 0.5 to 3, more preferably 1 to 2.5, and even more preferably 1.2 to 2.

[0019] The total content (b + c) of gypsum and pozzolanic substance is preferably 17 to 75 parts by mass, more preferably 20 to 60 parts by mass, even more preferably 25 to 50 parts by mass, and particularly preferably 27 to 40 parts by mass with respect to 100 parts by mass of cement. If the total content of gypsum and pozzolanic substance is within the above range, it makes it easier to mix the mortar and further improves the long-term strength development property.

[0020] (D) The hydroxycarboxylic acid-based setting retarder is not particularly limited as long as it is a carboxylic acid having a hydroxy group or a salt thereof. Examples of the hydroxycarboxylic acid include citric acid, gluconic acid, malic acid, tartaric acid, and maleic acid. When the hydroxycarboxylic acid is a salt, examples of the salt include sodium salt, potassium salt, calcium salt, and the like. As the hydroxycarboxylic acid-based setting retarder, citric acid, tartaric acid, gluconic acid, or their salts are preferred. The setting retarder may be in powder form or in liquid form (for example, in the form of an aqueous solution, emulsion, or suspension). The hydroxycarboxylic acid-based setting retarder may be used alone or in combination of two or more kinds.

[0021] The content (d) of the hydroxycarboxylic acid-based setting retarder is preferably 0.05 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.3 to 1 part by mass with respect to 100 parts by mass of cement. If the content of the hydroxycarboxylic acid-based setting retarder is within the above range, it is possible to sufficiently exhibit the long-term strength development property while moderately suppressing the short-term strength development property, and it is easy to secure the workable time.

[0022] The mass ratio (mass%, d / (b + c)×100) of the content (d) of the hydroxycarboxylic acid-based setting retarder to the total content (b + c) of gypsum and pozzolanic substances is preferably 0.1 to 15 mass%, more preferably 0.3 to 10 mass%, even more preferably 0.5 to 5 mass%, and particularly preferably 0.8 to 2 mass%. If the mass ratio of the hydroxycarboxylic acid-based setting retarder to the total mass of gypsum and pozzolanic substances is within the above range, it is possible to sufficiently exhibit the long-term strength development property while moderately suppressing the short-term strength development property, and it is easy to secure the workable time.

[0023] (E) Examples of fine aggregates include river sand, silica sand, crushed sand, gypsum, limestone sand, slag aggregates, etc. As the fine aggregate, it is preferable to use aggregates such as silica sand and limestone whose particle sizes are adjusted to a size that does not contain fine powder or coarse aggregates from among these. The fine aggregate may be used alone or in combination of two or more. As the fine aggregate, it is preferably those having a particle size of less than 5 mm (the fraction passing through a 5-mm sieve) which are commonly used, and more preferably those having a particle size of less than 2.5 mm (the fraction passing through a 2.5-mm sieve).

[0024] The particle size of the fine aggregate is not particularly limited and can be adjusted within the range of the required particle size of the fine aggregate. The particle size of the fine aggregate can be considered from the coarse grain ratio defined by JIS A 1102:2014 "Sieving Test Method for Aggregates". From the viewpoint that better fluidity is easily obtained and bleeding is easily suppressed during mortar, the coarse grain ratio of the fine aggregate is preferably 1 to 4, more preferably 1.5 to 3.8, and most preferably 2 to 3.5.

[0025] The content (e) of the fine aggregate is preferably 80 to 640 parts by mass, more preferably 200 to 550 parts by mass, and still more preferably 280 to 450 parts by mass with respect to 100 parts by mass of cement. If the content of the fine aggregate is within the above range, good fluidity is easily obtained.

[0026] The mortar composition of this embodiment may contain (F) an expansive agent. Any expansive agent may be used as long as it is a JIS-compliant expansive agent (JIS A 6202:2008) generally used as an expansive agent for concrete. Examples of the expansive agent include an expansive agent mainly composed of free quicklime (quicklime-based expansive agent), an expansive agent mainly composed of ettringite (ettringite-based expansive agent), and a composite expansive agent of free quicklime and ettringite-forming substances. The expansive agent may be used alone or in combination of two or more. It is preferable to use an expansive agent having a Blaine specific surface area of 2000 to 6000 cm 2 / g.

[0027] The content (f) of the expansion agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and still more preferably 1 to 5 parts by mass with respect to 100 parts by mass of cement. If the content of the expansion agent is within the above range, the early and long-term strength development properties, dimensional change rate, etc. will be even more excellent.

[0028] The mortar composition of the present embodiment may contain (G) a water reducing agent. The water reducing agent is generally selected from a high performance water reducing agent, a high performance AE water reducing agent, or an AE water reducing agent and a fluidizing agent. Examples of such water reducing agents include water reducing agents defined in JIS A 6204:2011 "Chemical admixtures for concrete". Examples of the water reducing agent include a polycarboxylic acid type water reducing agent, a naphthalene sulfonic acid type water reducing agent, a lignin sulfonic acid type water reducing agent, and a melamine type water reducing agent. Among these, a polycarboxylic acid type water reducing agent is preferred. The water reducing agent may be used alone or in combination of two or more.

[0029] The content (g) of the water reducing agent is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and still more preferably 0.5 to 1.5 parts by mass in terms of solid content with respect to 100 parts by mass of cement. If the content of the water reducing agent is within the above range, better fluidity is likely to be obtained when made into mortar.

[0030] The mortar composition of the present embodiment may contain (H) a thickening agent. The type of the thickening agent is not particularly limited as long as it is used for concrete, and examples include a cellulose type thickening agent, an acrylic type thickening agent, and a guar gum type thickening agent. A cellulose type thickening agent is preferred as the thickening agent. Examples of the cellulose type thickening agent include methyl cellulose type such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. The thickening agent may be used alone or in combination of two or more.

[0031] The content (h) of the thickener is preferably 0.01 to 2 parts by mass, more preferably 0.02 to 1 part by mass, and most preferably 0.03 to 0.5 part by mass in terms of solid content based on 100 parts by mass of cement. If the content of the thickener is within the above range, better fluidity is likely to be obtained when made into mortar, and the compressive strength is also likely to be improved.

[0032] In the mortar composition of this embodiment, various other admixtures (materials) may be blended as long as the effects of the present invention are not impaired. Examples of the admixtures (materials) include accelerating agents, foaming agents, defoaming agents, waterproof agents, rust preventives, shrinkage reducing agents, water retention agents, pigments, water repellents, efflorescence preventives, fibers, and the like.

[0033] The mortar composition of this embodiment can be prepared by mixing the above-described components with a commonly used kneading device, and the device is not particularly limited. Examples of the kneading device include a hand mixer, a tilting drum mixer, a pan-type mixer, a twin-screw mixer, and the like.

[0034] The mortar composition of this embodiment can be mixed with water to prepare mortar, and the water content can be appropriately adjusted according to the application. The water content is preferably 35 to 55 parts by mass, more preferably 40 to 53 parts by mass, and still more preferably 45 to 50 parts by mass based on 100 parts by mass of cement. If the water content is within the above range, it is easier to ensure fluidity, and it is easier to suppress the occurrence of material separation, the increase in shrinkage of the hardened body, and the decrease in initial strength development.

[0035] For the preparation of the mortar of this embodiment, the same kneading devices as those for ordinary mortar can be used, and it is not particularly limited. For example, those described above can be used as the kneading device.

[0036] The mortar of this embodiment, when hardened, has a compressive strength at an age of 1 day measured at 20 °C in accordance with JIS A 1108:2018 "Test Method for Compressive Strength of Concrete" of 10 N / mm 2 It is preferably as follows, 5 N / mm2 More preferably, it is as follows, 3 N / mm 2 More preferably, it is as follows. The compressive strength at 1 day of age is 0.5 N / mm 2 It may be above. If the compressive strength at 1 day of age is within the above range, it becomes easy to secure the pot life.

[0037] The mortar of this embodiment, when cured, has a compressive strength at 28 days of age measured in a 20°C environment according to JIS A 1108:2018 "Test Method for Compressive Strength of Concrete" of 58 N / mm 2 It is preferably above, 65 N / mm 2 More preferably, it is above, 70 N / mm 2 More preferably, it is above. The compressive strength at 28 days of age is 140 N / mm 2 It may be below. If the compressive strength at 28 days of age is within the above range, the long-term strength development property can be further exhibited. If the compressive strength at the time of hardening of the mortar at 1 day of age and 28 days of age is within the above range, it is easy to realize long-term strength development while securing a sufficient pot life, so while further securing the construction time, the durability can be further improved.

[0038] The mortar of this embodiment preferably has a 15-beat flow value of the mortar in a 20°C environment measured according to JIS R 5201:2015 "Physical Test Methods for Cement" 12. Flow Test of 140 to 200 mm, more preferably 145 to 190 mm, and even more preferably 150 to 180 mm. If the 15-beat flow value of the mortar is within the above range, the elongation of the mortar is good, so the workability is further improved, and it is easy to perform plastering methods such as trowel finishing and compaction methods using a vibrator.

[0039] The mortar composition and mortar of the present embodiment have a sufficient workable time and exhibit good strength development over a long period after hardening. Therefore, the mortar composition and mortar of the present embodiment can ensure sufficient time for construction even in a high-temperature environment such as in summer, and can be suitably used for various structures and on-site repairs and reinforcements that require excellent strength development. The construction method is not particularly limited, and plastering methods such as trowel finishing and compaction methods using a vibrator can be adopted.

[0040] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. All experiments were conducted under an environment of 20°C.

[0041] [Materials] (A) Cement: Early-strength cement, Blaine specific surface area 4500 cm 2 / g (B) Gypsum: Blaine specific surface area 7000 cm 2 / g (C) Pozolanic material: (c1) Silica fume, BET specific surface area 20 m 2 / g (c2) Silica fume, BET specific surface area 12 m 2 / g (c3) Metakaolin, BET specific surface area 10 m 2 / g (D) Setting retarder: (d1) Citric acid (d2) L-Tartaric acid (d3) Sodium gluconate (d4) Sodium acetate (d5) Boric acid (E) Fine aggregate: Silica sand, coarse grain ratio 2.65, maximum particle size less than 2.5 mm (F) Expansive agent: Quicklime-based expansive agent, Blaine specific surface area 3000 cm 2 / g (G) Water reducer: Polycarboxylic acid-based high-performance water reducer (H) Thickening agent: Methyl cellulose-based thickening agent

[0042] [Mix design of mortar composition] (A) For 100 parts by mass of cement, the proportions of (B) gypsum, (C) pozzolanic material, and (D) setting retarder are shown in Table 1. For (E) fine aggregate, 415 parts by mass, (F) expansive agent, 2.5 parts by mass, (G) water reducing agent, 0.8 parts by mass, and (H) thickening agent, 0.05 parts by mass were used to design the mortar composition of each example.

[0043] [Preparation of Mortar] In an environment at 20 °C, for each material of the mortar composition of each example designed in Table 1, 48 parts by mass of water was added per 100 parts by mass of cement, and the mixture was kneaded with a hand mixer for 120 seconds to prepare approximately 2 L of mortar.

[0044]

Table 1

[0045] [Evaluation Method] For the mortar of each example, each item was evaluated by the following method. The evaluation results are shown in Table 2. Since No. 3 and No. 7 were difficult to knead, no evaluation tests were conducted. ·Flow value (consistency) In accordance with JIS R 5201:2015 "Physical Testing Methods for Cement", item 12. Flow Test, the 15-beat flow value of the mortar in the fresh state was measured at 20 °C. This was evaluated as the consistency. ·Compressive strength In accordance with JIS A 1108:2018 "Test Method for Compressive Strength of Concrete", the compressive strength at the ages of 1 day and 28 days was measured. The dimensions of the test specimens were 50 mm in diameter and 100 mm in height. The test specimens at the age of 28 days were sealed and cured until the age of 7 days, and then cured in water until the age of the specimen. Curing was always carried out in a constant temperature bath at 20 °C. In addition, when the compressive strength at the age of 28 days was 60 N / mm 2 or more and the strength elongation ratio (compressive strength at the age of 28 days / compressive strength at the age of 1 day) was 10 or more, it was judged that the strength development was good (○). Otherwise, it was judged as poor (×).

[0046]

Table 2

[0047] The mortar of the example had a good 15-beat flow value and good elongation. At the age of 1 day, it was 10 N / mm 2 or less, so a sufficient pot life was obtained. At the age of 28 days, it was 58 N / mm 2 or more, so it was excellent in long-term strength development. On the other hand, some of the mortars of the comparative examples were difficult to mix, had a compression strength that was too high at 1 day to ensure a pot life, and did not obtain sufficient compression strength at 28 days.

Claims

1. (A) cement, (B) gypsum, (C) pozzolanic substance, (D) hydroxycarboxylic acid-based setting retarder, and (E) fine aggregate, and the content of component (B) is 16 to 49 parts by mass with respect to 100 parts by mass of component (A), a mortar composition in which the mass ratio (b / c) of component (B) to component (C) is 0.2 to 3.

25.

2. The mortar composition according to Claim 1, further comprising (F) an expansion agent.

3. The mortar composition according to Claim 1 or 2, wherein the total content (b + c) of components (B) and (C) is 17 to 74 parts by mass with respect to 100 parts by mass of component (A).

4. A mortar comprising the mortar composition according to Claim 1 or 2 and water, wherein the content of the water is 35 to 55 parts by mass with respect to 100 parts by mass of the cement.

5. At the time of hardening, the compressive strength at 1 day of age measured under an environment of 20 °C in accordance with JIS A 1108:2018 "Test Method for Compressive Strength of Concrete" is 10 N / mm ２ or less, and the compressive strength at 28 days of age is 58 N / mm ２ or more. The mortar according to claim 4.

6. The mortar according to Claim 4, wherein the 15-beat flow value of the mortar, measured in an environment at 20°C in accordance with JIS R 5201:2015 "Physical Test Methods for Cement", is 140 to 200 mm.

Images