Mortar composition and mortar

Abstract

To provide a mortar composition and a mortar exhibiting superior working time and superior quick-setting performance.SOLUTION: A mortar composition comprises a binder composed of cement, calcium aluminate slag, and gypsum materials, and fine aggregate. The content of the fine aggregate is 45-290 pts.mass relative to 100 pts.mass of the binder.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] It is widely known that calcium aluminate, the main component of multifunctional cement with rapid hardening and quick setting properties, can exhibit excellent rapid hardening and quick setting properties when used in combination with Portland cement, which is generally used in the civil engineering and construction fields and whose main component is calcium silicate (see, for example, Patent Document 1).

[0003] In addition to the above methods, cementitious hydraulic materials often use inorganic accelerators such as nitrites, thiocyanates, sulfates, and carbonates to further accelerate the hydration reaction and increase early strength. On the other hand, to ensure the workability of fresh mortar, carboxylic acids, alkali metal carbonates, boric acids, polyacrylic acids, and other set retarders are added. These opposing admixtures are often used in combination with other cementitious hydraulic materials, with appropriate amounts of each additive determined in advance. To ensure workability, polyol complexes, lignin sulfonates and their derivatives, and water-reducing agents based on hydroxycarboxylates, naphthalene sulfonates, melamine sulfonates, and polycarboxylic acid-based high-performance water-reducing agents are also commonly used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-156484 Summary of the Invention [Problem to be solved by the invention]

[0005] Rapid-setting mortars containing calcium aluminate often have short pot life and setting times, making them difficult to handle. The most inexpensive way to extend pot life is to increase the amount of mixing water. However, increasing the amount of mixing water has many drawbacks, including material segregation and reduced strength. While various set retarders can adjust pot life without compromising the fresh mortar's resistance to material segregation and strength development after hardening, when used in combination with various water-reducing admixtures, the set retarding effect of the water-reducing admixture itself must be taken into account, and determining the amount of these admixtures can require skilled techniques. Therefore, there is a need for rapid-setting mortars that offer excellent pot life while maintaining rapid hardening properties through methods other than water volume or set retarders.

[0006] Therefore, an object of the present invention is to provide a mortar composition and a mortar that are excellent in pot life and rapid hardening property. [Means for solving the problem]

[0007] As a result of intensive research into the above-mentioned problems, the present inventors have found that by using calcium aluminate slag, which is generated as a by-product during metal refining, it is possible to achieve a longer pot life and maintain rapid hardening properties than by using calcium aluminate calcined from a calcium source and an aluminum source.

[0008] That is, the present invention is as follows. [1] A mortar composition comprising a binder made of cement, calcium aluminate slag, and gypsum, and a fine aggregate, wherein the content of the fine aggregate is 45 to 290 parts by mass per 100 parts by mass of the binder. [2] The mortar composition according to [1], wherein the calcium aluminate slag contains, as chemical substances, a molar ratio of CaO to Al2O3 (CaO / Al2O3 molar ratio) of 0.8 to 1.4. [3] A mortar composition according to [1] or [2], wherein the total content of titanium and iron as chemical substances in the calcium aluminate slag is 3 mass% or less in terms of oxides. [4] The mortar composition according to [1] or [2], wherein the cement content is 40 to 90 parts by mass per 100 parts by mass of the binder. [5] A mortar containing the mortar composition according to [1] or [2] and water, wherein the water content is 30 to 50 parts by mass per 100 parts by mass of the binder. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a mortar composition and a mortar that are excellent in pot life and rapid hardening property. DETAILED DESCRIPTION OF THE INVENTION

[0010] A preferred embodiment of the present invention will be described below. The contents described in this specification are on a solid content basis and an anhydrous basis.

[0011] The mortar composition of this embodiment contains cement, a binder made of calcium aluminate slag and gypsum, and fine aggregate.

[0012] The binder according to this embodiment is composed of three components: cement, calcium aluminate slag, and gypsum.

[0013] Various cements can be used, including, for example, various Portland cements such as ordinary, early-strength, ultra-early-strength, low-heat, and moderate-heat; blended cements containing blast furnace slag, fly ash, or silica fume; and ecocement. Ordinary Portland cement or early-strength Portland cement is preferred as the cement, as it is easy to achieve both improved strength development and fluidity. One type of cement may be used alone, or two or more types may be used in combination.

[0014] The cement content is preferably 40 to 90 parts by mass, more preferably 50 to 85 parts by mass, and even more preferably 60 to 82 parts by mass, relative to 100 parts by mass of the binder. If the cement content is within the above range, it is easy to ensure both a sufficient pot life and excellent initial strength development.

[0015] Calcium aluminate slag is a by-product of metal refining, specifically calcium aluminate slag produced during the refining of nickel, molybdenum, vanadium, etc., or alloys with iron such as ferronickel and ferrovanadium.

[0016] As for the chemical components of calcium aluminate slag, the CaO / Al2O3 molar ratio is preferably 0.8 to 1.4, more preferably 0.85 to 1.25, and even more preferably 0.9 to 1.15. When the CaO / Al2O3 molar ratio is within the above range, it is easy to ensure both a long working life and excellent initial strength development.

[0017] Examples of mineral phases of calcium aluminate slag include krotite (CaO·Al2O3), mayenite (12CaO·7Al2O3), gehlenite (2CaO·Al2O3·SiO2), calcium aluminoferrite (4CaO·Al2O3·Fe2O3), periclase (MgO), and akermanite (2CaO·MgO·2SiO2). Among these, those containing krotite as the main component (50% by mass or more) are preferred. From the viewpoint of achieving even better initial strength development, calcium aluminate slag preferably contains mayenite. From the viewpoint of easily achieving both a long working life and excellent initial strength development, the mayenite content is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 8% by mass.

[0018] Calcium aluminate slag may contain small amounts of metals and metal oxides, such as titanium, iron, nickel, molybdenum, vanadium, chromium, and cobalt. The metal and metal oxide content is preferably 5% by mass or less in terms of metal oxide.

[0019] In calcium aluminate slag, the content of titanium as a chemical substance is preferably 2 mass% or less, more preferably 1.5 mass% or less, even more preferably 1 mass% or less, and particularly preferably 0.7 mass% or less, calculated as oxide (TiO). In calcium aluminate slag, the content of iron as a chemical substance, calculated as oxide (Fe2O3), is preferably 2 mass% or less, more preferably 1.5 mass% or less, even more preferably 1 mass% or less, and particularly preferably 0.7 mass% or less. In the calcium aluminate slag, the total content of titanium and iron as chemical substances is preferably 3 mass% or less, more preferably 2 mass% or less, even more preferably 1.5 mass% or less, and particularly preferably 1.2 mass% or less, calculated as oxides. In calcium aluminate slag, if the contents of titanium and iron as chemical substances are within the above ranges, it is easy to ensure both a long working life and excellent initial strength development.

[0020] The mineral phase and chemical composition of calcium aluminate slag can be measured using an X-ray diffractometer by the calibration curve method, the Rietveld method, or the like.

[0021] The ignition loss of calcium aluminate slag usually increases (indicated by a + sign). Here, ignition loss refers to the weight loss when heated in air at 950°C for one hour. The increase in ignition loss is thought to be due to the transition metals contained in the slag remaining in the metallic state or in the form of low-valence compounds.

[0022] Calcium aluminate slag is usually cooled naturally, so the product is essentially crystalline. The vitrification rate is not particularly limited, but is typically less than 20% by mass. The vitrification rate can be measured using an X-ray diffractometer, either by the calibration curve method or the Rietveld method.

[0023] Calcium aluminate slag, which is usually produced as a by-product during metal refining, is obtained as a lump. Therefore, calcium aluminate slag is pulverized into powder. The pulverization method is not particularly limited, and for example, calcium aluminate slag can be roughly crushed using a crusher mill or the like, and then finely pulverized using a ball mill, vibration mill, or the like. The fineness of calcium aluminate slag is 3000 to 8000 cm in terms of Blaine specific surface area. 2 / g, and 4000 to 7000 cm 2 / g is more preferred.

[0024] The content of calcium aluminate slag is preferably 5 to 50 parts by mass, more preferably 7 to 40 parts by mass, and even more preferably 9 to 30 parts by mass, relative to 100 parts by mass of the binder. If the content of calcium aluminate slag is within the above range, it is easy to ensure both a sufficient pot life and excellent initial strength development.

[0025] 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. From the viewpoint of further improving long-term strength development, the fineness of the gypsum is set to 3000 cm in terms of Blaine specific surface area. 2 / g or more, and 2 / g or more. The fineness of gypsum is preferably 15,000 cm in terms of Blaine specific surface area. 2 / g or less is preferable.

[0026] The content of the gypsum is preferably 3 to 18 parts by mass, more preferably 5 to 15 parts by mass, and even more preferably 7 to 12 parts by mass, in anhydrous equivalent relative to 100 parts by mass of the binder. If the content of the gypsum is within the above range, it is easy to achieve both initial and long-term strength development.

[0027] Examples of fine aggregate include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. Of these, it is preferable to use silica sand, limestone sand, etc., 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 aggregate with a particle size of 5 mm or less (passing through a 5 mm sieve), which is commonly used.

[0028] 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 considered based on the coarse particle ratio specified in JIS A 1102:2014 "Sieving Test Method for Aggregates." From the viewpoint of obtaining better fluidity when made into mortar and suppressing bleeding, the coarse particle ratio of the fine aggregate is preferably 1 to 4, more preferably 1.2 to 3.8, and even more preferably 1.3 to 3.7.

[0029] The content of fine aggregate is 45 to 290 parts by mass relative to 100 parts by mass of binder. If the content of fine aggregate is outside this range, there is a risk that the pot life cannot be ensured or that initial strength development cannot be obtained. From the viewpoint of easily achieving both a long pot life and excellent initial strength development, the content of fine aggregate is preferably 50 to 250 parts by mass, more preferably 60 to 200 parts by mass, and even more preferably 65 to 150 parts by mass relative to 100 parts by mass of binder.

[0030] The mortar composition of this embodiment may contain a set retarder. By including a set retarder, it becomes easier to ensure a sufficient working life even in the summer when the temperature of the mixed cement paste is high. Examples of set retarders include organic acids or salts thereof, such as citric acid, gluconic acid, malic acid, and tartaric acid; boric acid, borates such as sodium borate, phosphates, alkali metal carbonates, and alkali metal bicarbonates; and sugars. Among these, citric acid, citrates, tartaric acid, tartrates, and alkali metal carbonates are preferred. The set retarder may be in the form of a powder or a liquid (e.g., an aqueous solution, emulsion, or suspension). One type of set retarder may be used alone, or two or more types may be used in combination.

[0031] The content of the setting retarder is preferably 0.01 to 2 parts by mass, more preferably 0.03 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass, relative to 100 parts by mass of the binder. If the content of the setting retarder is within the above range, it is easier to ensure a longer pot life and the early strength development is less likely to decrease.

[0032] The mortar composition of this embodiment may contain a water-reducing agent. Examples of 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, naphthalenesulfonic acid-based water-reducing agents, ligninsulfonic acid-based water-reducing agents, and melamine-based water-reducing agents. Of these, naphthalenesulfonic 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.

[0033] The content of the water-reducing agent is preferably 0.01 to 2 parts by mass, more preferably 0.03 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass, in terms of solid content per 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 the mortar is made into a mortar.

[0034] The mortar composition of this embodiment may contain various admixtures (materials) within the range that does not impair the effects of the present invention. Examples of admixtures (materials) include expanding agents, thickeners, foaming agents, antifoaming agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, water retention agents, pigments, water repellents, anti-efflorescence agents, and fibers.

[0035] The mortar composition of the present embodiment can be prepared by mixing the above-described components using a commonly used kneading tool, and the tool is not particularly limited. Examples of the kneading tool include a hand mixer, a tilting mixer, a pan mixer, and a twin-screw mixer.

[0036] The mortar composition of this embodiment can be prepared as a mortar by mixing with water, and the water content can be adjusted appropriately depending on the application. The water content is preferably 30 to 50 parts by mass, more preferably 32 to 48 parts by mass, and even more preferably 35 to 45 parts by mass, per 100 parts by mass of binder. If the water content is within the above range, it is easier to ensure fluidity and to suppress the occurrence of material separation, increased shrinkage of the hardened body, and a decrease in initial strength development.

[0037] The preparation of the mortar of this embodiment can be carried out using the same kneading equipment as that used for ordinary mortar, and is not particularly limited. For example, the kneading equipment described above can be used.

[0038] The mortar of this embodiment has a compressive strength of 1 N / mm2 at 3 hours after hardening, measured in a 20°C environment in accordance with JIS A 1108:2018 "Test method for compressive strength of concrete." 2 It is preferable that the resistance is 3N / mm or more. 2 More preferably, it is 5N / mm 2 If the compressive strength at 3 hours is within the above range, the initial strength development is excellent, and the mortar can be easily used as a fast-hardening mortar.

[0039] The mortar composition and mortar of this embodiment have excellent rapid hardening properties because they have a sufficient pot life and exhibit good initial strength development. Therefore, the mortar composition and mortar of this embodiment can be suitably used in construction sites where construction time is limited, and can be suitably used for repairing and reinforcing various structures and construction sites. The construction method is not particularly limited, and plastering methods such as trowel finishing and compaction methods using a vibrator can be used. [Example]

[0040] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. All examples were carried out in an environment of 20°C.

[0041] [material] Cement: Ordinary Portland cement Calcium aluminate slag (CAS): CaO / Al2O3 molar ratio 1.1. Details of the chemical composition are shown in Table 1. Calcium aluminate 1 (CA1): Commercially available calcined product, CaO / Al2O3 molar ratio 1.3. Contains 2.42 mass% titanium (TiO2) and 1.05 mass% iron (Fe2O3). Calcium aluminate 2 (CA2): Commercially available calcined product with a CaO / Al2O3 molar ratio of 1.4. Contains 2.30 mass% titanium (TiO2) and 1.95 mass% iron (Fe2O3). Gypsum: Commercially available products, anhydrous gypsum Fine aggregate: silica sand, coarse grain ratio 1.69 Set retarder: citric acid Water reducing agent: Naphthalene sulfonic acid water reducing agent

[0042] [Calcium aluminate slag] Calcium aluminate slag generated during metal refining was used. It was produced as ferrovanadium slag after refining. The chemical composition of the calcium aluminate slag is shown in Table 1. This calcium aluminate slag contained 0.66 mass% vanadium (V2O3) in terms of oxide, 0.07 mass% titanium (TiO2) in terms of oxide, and 0.2 mass% iron (Fe2O3) in terms of oxide. The CaO / Al2O3 molar ratio was 1.1, and the loss on ignition was +0.25 mass% (gain). The mineral composition included 80 mass% krotite, 5 mass% mayenite, 10 mass% gehlenite, and 2 mass% periclase. The vitrification ratio was 2%. The mineral content and vitrification ratio were calculated using an X-ray diffractometer by the Rietveld method. This calcium aluminate slag was coarsely crushed and then pulverized in a ball mill to obtain a powder with a Blaine specific surface area of ​​5020 cm 2 / g of powder.

[0043] [Table 1]

[0044] [Preparation of mortar composition and mortar] Portland cement, calcium aluminate slag or calcium aluminate, gypsum, fine aggregate, a setting retarder, and a water-reducing agent were mixed in the proportions shown in Table 2 to prepare mortar compositions. The mortar composition and water were mixed in a 10 L cylindrical container and mixed for 90 seconds with a hand mixer to prepare a mortar. 40 parts by mass of water was added to 100 parts of the mortar composition.

[0045] [Table 2]

[0046] [Evaluation method] The various mortars were evaluated using the following evaluation methods. The results are shown in Table 3. Each test was carried out in an environment of 20°C. Gel Time The usable time was evaluated by gel time. The mixed mortar was placed in a 300 mL transparent plastic container and poured into another transparent plastic container every minute. The time when fluidity was confirmed was taken as the gel time. A gel time of 3 minutes or more was judged to be good. Mortar that did not move during the first transfer of the plastic container was judged to have no fluidity. ·Bag curing time Setting time was evaluated based on the bag hardening time. The mixed mortar was placed in a plastic bag, and the time it took for the mortar to harden to the point where it no longer deformed when pressed by hand was measured and evaluated. Bag hardening times of 13 minutes or more were considered good. Bag hardening times of 60 minutes or more were considered unmeasurable. Compression strength After mixing, the mortar was quickly poured into a 5x10cm diameter formwork and sealed. The specimen was then demolded 3 hours after mixing began, and a compressive strength test was carried out in accordance with JIS A 1108:2018 "Test method for compressive strength of concrete." The formwork was left sealed and cured until the material was 3 hours old. At this time, the specimen was covered with a polyvinyl chloride sheet to prevent moisture from escaping from the poured surface. The top surface of the poured specimen was not polished, and a compression test was carried out with one side unbonded capping. The compressive strength at 3 hours was 1N / mm 2 The above was judged to be good.

[0047] [Table 3]

[0048] The mortars of the Examples had good gel times and bag hardening times, and also had sufficient compressive strength at an age of 3 hours, so they achieved both usable time and rapid hardening. On the other hand, the mortar of Comparative Example 1 hardened slowly, and its compressive strength could not be measured at the 3-hour mark. The mortar of Comparative Example 2 had a short gel time and did not have sufficient usable time. The mortars of Comparative Examples 3 and 4 quickly lost fluidity and had almost no usable time.

Claims

1. The composition includes a binder made of cement, calcium aluminate slag, and gypsum, and fine aggregate, The mortar composition, wherein the content of the fine aggregate is 45 to 290 parts by mass per 100 parts by mass of the binder.

2. In the calcium aluminate slag, the chemical substances are CaO and Al ２ O ３ The molar ratio of CaO / Al ２ O ３ The mortar composition according to claim 1, wherein the molar ratio is 0.8 to 1.

4.

3. 3. The mortar composition according to claim 1, wherein the calcium aluminate slag has a total content of titanium and iron as chemical substances of 3 mass % or less in terms of oxides.

4. The mortar composition according to claim 1 or 2, wherein the content of the cement is 40 to 90 parts by mass per 100 parts by mass of the binder.

5. A mortar composition comprising the mortar composition according to claim 1 or 2 and water, The mortar has a water content of 30 to 50 parts by mass per 100 parts by mass of the binder.

Images