Cement composition and ultra-high strength, low shrinkage mortar composition

Abstract

To provide an ultra-high-strength and low-shrinkage cement composition capable of suppressing an amount of shrinkage while maintaining sufficient compressive strength even for ultra-high-strength mortar or concrete having a compressive strength of over 100 N / mm2.SOLUTION: The cement composition contains cement, the following two types of glassy materials, and anhydrous gypsum. (1)Silicate glass powder having a vitrification ratio of 80% or more, and SiO2 of 90 mass% or more as a chemical composition of a vitreous portion, (2)Aluminosilicate glass powder having a vitrification ratio of 80% or more, and Al2O3 of 40 to 50 mass% and SiO2 of 50 to 60 mass% as a chemical composition of the vitreous portion.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to ultra-high strength mortar and concrete for use in construction and other applications. [Background technology]

[0002] A technique for adding ultrafine powder such as silica fume to cement paste, mortar, concrete, etc. used in construction applications to impart high strength has been known for some time (see, for example, Patent Document 1). At present, the technology is capable of increasing compressive strength to 100 N / mm by adding silica fume fine powder and achieving a low water-binder ratio. 2 Ultra-high strength concrete that exceeds this has been designed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-156168 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to ensure compressive strength in high-strength concrete, the amount of binder such as cement must be increased, making it difficult to suppress shrinkage caused by hydration from the early stage of the material's life. The present invention has a compressive strength of 100N / mm 2 The object of the present invention is to provide an ultra-high strength, low shrinkage mortar composition which can suppress the amount of shrinkage while maintaining sufficient compressive strength, even in the case of ultra-high strength mortar and concrete exceeding 1000 kPa (1.0 kgf / cm2). [Means for solving the problem]

[0005] As a result of extensive research, the inventors of the present invention have found that by combining two types of glassy materials with different compositions with Portland cement, it is possible to increase the compressive strength to 100 N / mm 2The present inventors have found that it is possible to reduce initial shrinkage while maintaining ultra-high strength exceeding 1000 g / m2, and have completed the present invention. That is, the present invention relates to a cement composition and an ultra-high strength, low shrinkage mortar composition which solve the above problems by having the following constitutions. [1] A cement composition containing cement, the following two types of vitreous materials, and anhydrous gypsum: (1) a silicate glass powder having a vitrification rate of 80% or more and a chemical composition of the vitreous portion of SiO2 of 90% by mass or more, (2) an aluminosilicate glass powder having a vitrification rate of 80% or more and a chemical composition of the vitreous portion of Al2O3 of 40-50% by mass and SiO2 of 50-60% by mass. [2] An ultra-high strength, low shrinkage mortar composition comprising the cement composition, a dispersant, aggregate and water, the amount of water being 18 to 32 parts by mass per 100 parts by mass of the cement composition. Effect of the Invention

[0006] This invention relates to ultra-high strength mortar and concrete for use in construction and other applications, with a compressive strength of 100 N / mm 2 It is possible to provide a cement composition capable of reducing initial shrinkage while maintaining ultra-high strength exceeding 100%, and an ultra-strength, low-shrinkage mortar composition using the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will be specifically described below. <Cement composition> The cement composition of the present invention contains cement, two types of vitreous materials, and anhydrous gypsum.

[0008] The cement used in the present invention may be Portland cement, mixed cement, etc., but Portland cement is preferable from the viewpoint of strength development and shrinkage suppression. One type of cement may be used alone, or two or more types may be used in combination.

[0009] The vitreous material used in the present invention is of two different compositions. The first vitreous material (1) is a silicate glass powder having a vitrification rate of 80% or more and a chemical composition of the vitreous portion of SiO2 of 90% by mass or more. From the viewpoint of ensuring high strength, the vitrification rate must be 80% or more, and more preferably 90% or more. Also, from the viewpoint of ensuring low shrinkage, the chemical composition of the vitreous portion must be SiO2 90% by mass or more, and preferably 95% by mass or more. An example of such a silicate glass powder is silica fume. The fineness of the silicate glass powder is 10 to 25 m in terms of BET specific surface area. 2 / g is preferred.

[0010] The second vitreous material (2) is an aluminosilicate glass powder having a vitrification rate of 80% or more and a chemical composition of the vitreous portion consisting of 40-50% by mass of Al2O3 and 50-60% by mass of SiO2. From the viewpoint of ensuring high strength, the vitrification rate must be 80% or more, and more preferably 90% or more. The chemical composition of the vitreous portion must be 40-50% by mass of Al2O3 and 50-60% by mass of SiO2. If SiO2 is less than 50% by mass, vitrification is difficult, and if Al2O3 is less than 40% by mass, there is a risk of excessive shrinkage. Metakaolin and the like are examples of such aluminosilicate glass powders. The fineness of the aluminosilicate glass powder is 6-15 m in terms of BET specific surface area. 2 / g is preferred.

[0011] The anhydrous gypsum used in the present invention includes natural anhydrous gypsum, hydrofluoric anhydrous gypsum produced as a by-product, and recycled anhydrous gypsum produced from waste gypsum board. The form of anhydrous gypsum includes type I, type II, and type III, of which type II anhydrous gypsum is preferred. By using type II anhydrous gypsum, there is a possibility that shrinkage, especially in the early stages, can be suppressed. The fineness of the anhydrous gypsum is 3000 to 20000 cm in terms of Blaine specific surface area. 2 / g is preferred.

[0012] The blending ratio of each of the constituent materials in the cement composition of the present invention is preferably 50 to 85 mass % of cement, 5 to 15 mass % of the vitreous material (1), 5 to 15 mass % of the vitreous material (2), and 1 to 15 mass % of anhydrous gypsum.

[0013] <High-strength, low-shrinkage mortar composition> The high-strength, low-shrinkage mortar composition of the present invention contains the above-mentioned cement composition, a dispersant, aggregate and water. Here, the mortar composition includes a concrete composition using coarse aggregate as the aggregate.

[0014] As the aggregate used in the present invention, fine aggregates such as crushed sand, river sand, sea sand, etc., which are usually used in mortar and concrete, and coarse aggregates such as crushed stone, etc., can be used, but from the viewpoint of strength development, it is preferable to use aggregates with high compressive strength themselves, and lightweight aggregates with low compressive strength are excluded. The amount of aggregate to be mixed is preferably 80 to 800 parts by mass with respect to 100 parts by mass of the cement composition.

[0015] As the dispersant used in the present invention, various water reducing agents usually used in mortar and concrete can be used, but polycarboxylate-based ones are preferable because they are easy to ensure fluidity when mixed for high strength. The amount of dispersant added is preferably 0.05 to 1 part by mass in terms of solid content per 100 parts by mass of the cement composition.

[0016] The water used in the present invention may be any water, such as tap water, groundwater, etc. The amount of water to be added is preferably 18 to 32 parts by mass, more preferably 20 to 30 parts by mass, per 100 parts by mass of the cement composition, from the viewpoint of ensuring high strength and workability.

[0017] As long as the effect of the present invention is not impaired, other components than those described above may be contained, such as, for example, an expanding agent, a shrinkage reducing agent, an antifoaming agent, an air entraining agent, inorganic fine powders such as silica powder and limestone fine powder, fibers, pigments, etc. EXAMPLES

[0018] EXAMPLES Hereinafter, examples of the present invention will be described together with comparative examples, but the present invention is not limited to the described examples.

[0019] <Preparation of cement composition and mortar composition> The components in the compounding ratios in Table 1 were mixed for 3 minutes in a constant temperature test room at 20° C. using a hand mixer (Toshiba, rotation speed 1000 rpm) to prepare test samples. The materials used are shown below. In addition, dispersants of The amount added was adjusted so that the flow value measured according to JIS R 5201 was 150±20 mm. Cement: Ordinary Portland cement (manufactured by Taiheiyo Cement Corporation) Vitreous material A: Vitrification rate: >95%, SiO2 in vitreous part: 95% (commercially available silica fume) - Vitreous material B: Vitrification rate: 91%, SiO2 in the vitreous part: 51%, Al2O3 in the vitreous part: 47% Glassy material C: Vitrification rate: 80%, SiO2 in glassy part: 52%, Al2O3 in glassy part: 43% · Glass materials D Vitrification rate: 81%, SiO2 in the vitreous part: 65%, Al2O3 in the vitreous part: 20% Vitreous material E; vitrification rate: 45%, SiO2 in the vitreous part: 51%, Al2O3 in the vitreous part: 43% Gypsum a: Type II anhydrous gypsum (manufactured by Pacific Materials, hydrofluoric anhydrous gypsum) Gypsum b: Type III anhydrous gypsum (manufactured by Nacord, recycled anhydrous gypsum from gypsum board raw materials) Gypsum c: Type I anhydrous gypsum (prepared by baking gypsum a in an electric furnace at 1200°C) Aggregate: JIS R 5201 Standard sand for cement strength testing (manufactured by the Cement Association Research Institute) Water; tap water Dispersant: Polycarboxylic acid-based high-performance water reducer Coreflow (manufactured by Pacific Materials Co., Ltd.)

[0020] [Table 1]

[0021] <Evaluation test> 1) Compressive strength measurement Each mortar composition was filled into a formwork measuring 5 cm in diameter x 10 cm, and after curing for 28 days in a water tank at 20°C, the compressive strength was measured in accordance with JIS A 1108. 2) Measurement of shrinkage amount Each mortar composition was filled into a formwork measuring 4 cm in diameter x 4 cm x 16 cm, and left to stand in a humid air box at 20°C. After 24 hours, the formwork was removed and the specimens were then left to stand in a constant temperature test room at 20°C and 60% RH. After 28 days, the amount of shrinkage was measured using a method in accordance with JIS A 1129 and used as an index of initial shrinkage.

[0022] <Test Results> The test results are shown in Table 2. The product of the present invention has a compressive strength of 100 N / mm 2 It can be seen that the shrinkage exceeds the limit and the amount of shrinkage is suppressed.

[0023] [Table 2]

Claims

1. A cement composition for use in an ultra-high strength, low shrinkage mortar composition, comprising: It contains Portland cement, the following two types of vitreous materials, and anhydrous gypsum, The Portland cement is 50 to 85% by mass, the following silicate glass powder is 5 to 15% by mass, the following aluminosilicate glass powder is 5 to 15% by mass, and the anhydrous gypsum is 1 to 15% by mass, and a total amount of the silicate glass powder, the aluminosilicate glass powder and the anhydrous gypsum is 42.8 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the Portland cement. (1) The vitrification rate is 80% or more, and the chemical composition of the vitreous part is SiO ２ 90% by mass or more, and the BET specific surface area is 10 to 25 m ２ / g silicate glass powder (2) The vitrification rate is 80% or more, and the chemical composition of the vitreous part is Al ２ O ３ 40 to 50 mass% and SiO ２ 50 to 60% by mass of aluminosilicate glass powder

2. A method for producing a cement composition comprising the cement composition according to claim 1, a dispersant, an aggregate and water, The cement composition is 100 parts by mass, and water is 18 to 32 parts by mass. The compressive strength at 28 days is 100 N / mm ２ and the shrinkage at 28 days measured by a method conforming to JIS A 1129 is 527 x 10 －６ An ultra-high strength, low shrinkage mortar composition, characterized in that:

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