JPH0450265B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a cured glass fiber reinforced cement body. Glass fiber reinforced cement (hereinafter referred to as GRC), which is a combination of cement and glass fiber, is used as a building material because it has superior bending strength properties compared to ordinary mortar and concrete. However, when Portland cement-based cement is used, the glass fibers are eroded by the alkali produced by the hydration of the cement, especially large amounts of calcium hydroxide based on tricalcium silicate, resulting in medium- to long-term material aging. The drawback was that the bending strength of the steel was greatly reduced. To eliminate this drawback, alkali-resistant glass fibers that are not eroded by cement hydration have been developed and utilized in GRC. but,
This alkali-resistant glass fiber (hereinafter referred to as ARG)
Even if ARG is used, erosion by the alkaline components of cement cannot be essentially prevented, so GRC obtained using these ARGs has not yet been able to completely prevent a decrease in bending strength. One of the further improved GRCs is the
Publication No. 55-121949 states that the main component is calcium alpha aluminate (3CaO, 3Al ₂ O ₃ , CaSO ₄ or less).
C ₃ A ₃ C), calcium sulfate (CaSO ₄ hereinafter referred to as C), and free lime (hereinafter referred to as f CaO), and the molar ratio of C to C ₃ A ₃ C is 1.6.
~6.5, and the matrix is made of a binder that does not substantially contain tricalcium silicate (hereinafter referred to as C ₃ S).
GRC is disclosed. However, since this GRC requires that the binding material used therein contain f-CaO, the setting time of the binding material is extremely short, so in the case of practical use, a large amount of setting retarder must be used together. is necessary. Furthermore, when producing GRC using this binder, it is nearly impossible to mix it with the same amount of water reducing agent as is normally used. Therefore, in order to obtain appropriate fluidity, it is necessary to increase the W/C, which in turn causes a decrease in strength. Furthermore, in order to mold with a W/C that does not cause a decrease in strength, a larger amount of water reducing agent than is generally used is required, which is also uneconomical. The present inventors have eliminated the drawbacks of conventional products, and have achieved that the bending strength in the long-term material age does not decrease significantly compared to the initial material age, and that there is no rapid setting or poor flowability during the kneading and curing process. As a result of research into a cured glass fiber-reinforced cement material that does not cause any problems in workability, etc., the following findings were obtained and the present invention was completed. (1) According to the present invention, a specific cement composition that does not produce calcium hydroxide during hydration hardening is used as a binder, and this and glass fiber, aggregate and water, or these and additives added as necessary. When the kneaded composition is cured, the glass fibers are not eroded and the bending strength of the obtained cured product during long-term aging is not reduced. (2) Since the cement composition does not contain f.CaO and has sufficient setting time, no setting retarder is required in normal use. (3) If the above cement composition is used, the amount of water reducing agent used will be halved compared to when a conventional binder is used, and this means that if W/C = constant, the above cement composition liquidity (flow value)
This is the result obtained from That is, the method for producing a cured glass fiber reinforced cement body of the present invention is characterized in that the following cement composition (hereinafter referred to as cement composition A) is used as a binder. Cement composition A; _C3A3C18 ~ _70wt % as a binder, C~
The main components are 35wt% and _C2S10 ~65wt%, of which _SO2 has _{a SO3} / _Al2O3 molar ratio of 0.4~1.7 and effective CaO.
is blended so that the effective CaO/Al ₂ O ₃ molar ratio is 0.5 to 1.2, and manufactured so that no f.CaO remains. The above effective CaO is a chemical component in cement composition A.
SiO ₂ , Fe ₂ O ₂ , SO ₃ , TiO ₂ , etc. are each 2CaO・
SiO ₂ , 4CaO・Al ₂ O ₃・Fe ₂ O ₃ , CaSO ₄ , 3CaO・
The amount of CaO consumed by each component is calculated according to the Borg formula, assuming that it combines with CaO in the form of 3TiO ₂ · CaSO ₄ ..., and the total amount is subtracted from the total amount of CaO. This cement composition A consists of calcareous raw materials (limestone, quicklime, etc.), alumina raw materials (bauxite,
clay, blast furnace slag, etc.), _SO3 materials (exhausted gypsum,
Using siliceous raw materials (silica clay, silica sand, etc.) (phosphogypsum, etc.), mix and crush them in a predetermined ratio,
SO _{3 /} Al ₂ of the cement composition manufactured from the clinker obtained by firing at 1200°C to 1350°C or the clinker to which hydraulic admixtures such as gypsum, slag, and plywood are added. It is obtained by adjusting the O ₃ molar ratio to 0.4 to 1.7. In order to prevent f.CaO from remaining in the clinker, it is important to blend the effective CaO so that the effective CaO/Al ₂ O ₃ molar ratio is 1.2 or less. The above C ₃ A ₃ C needs to be 18 to 70% by weight. If C ₃ A ₃ C is less than 18% by weight, the desired ultra-early strength cannot be obtained, and if it exceeds 70% by weight, ultra-early strength can be obtained, but it exhibits expansibility over time, causing a decrease in strength. As a result, expansion failure may occur. SO ₃ in this cement composition A is SO ₃ /
It is important that the Al ₂ O ₃ molar ratio is 0.4 to 1.7,
If it is less than 0.4, good ultra-early strength cannot be obtained,
When it exceeds 1.7, the specimen expands and cracks, resulting in a significant decrease in strength. In addition, residual C in the clinker
When S is 35% by weight or more, the SO ₃ /Al ₂ O ₃ molar ratio is
As in the case of 1.7 or higher, the specimen expands and cracks, resulting in a significant decrease in strength. When the effective CaO/Al ₂ O ₃ molar ratio exceeds 1.2, f・CaO will remain in the clinker, and although ultra early strength can be obtained,
It becomes difficult to obtain good flowability and sufficient working time. Therefore, it is necessary to ensure that virtually no f・CaO remains, and to do so, the effective CaO/
It is important that the Al ₂ O ₃ molar ratio is 1.2 or less.
However, as the effective CaO/Al ₂ O ₃ molar ratio falls below 1.2, gehlenite (2CaO・Al ₂ O ₃・SiO ₂ ,
Hereinafter referred to as C ₂ AS. ) will be formed and the molar ratio will be
When it is less than 0.5, the amount of C ₂ AS in the clinker increases, thereby decreasing the strength of the resulting cement composition A. In addition, when producing the cement composition A used in the present invention, if the composition contains a large amount of SO ₃ raw material, such that 35% by weight or more of C remains in the clinker, the clinker may become excessively fused during firing. Troubles are more likely to occur during kiln operation. For this reason, from the viewpoint of firing, it is desirable to perform firing within a range of raw material blends such that C in the clinker is 35% by weight or less. Of course, there is a method in which cement composition A is obtained by firing the clinker with a _{SO 3 /} Al ₂ O ₃ molar ratio of 0.4 to 1.7, and pulverizing it.
When considering problems such as clinker fusion in the kiln, the SO ₃ /Al ₂ O ₃ molar ratio in the clinker is
The clinker and gypsum obtained by mixing and firing the raw materials to a relatively low molar ratio, e.g. 0.2 to 0.4, are added to the desired _SO3 / _Al2O3 molar ratio (0.4 to 1.7 ₎ in cement composition A. ) It is also one method to produce the cement composition A of the present invention by mixing and pulverizing or separately pulverizing. However, in this case,
The SO ₃ /Al ₂ O ₃ molar ratio must not be less than 0.2;
If it is less than 20%, it will be difficult to obtain the desired amount of C ₃ A ₃ C in the clinker, which will cause quality fluctuations. Glass fibers include ARG or ordinary glass fiber (hereinafter referred to as EG), rock wool,
Any material such as slag fiber may be used. The amount added is preferably 1% or more based on the mortar, and if it is less than that, the contribution of the addition of fiber to the strength will not be small. Although it is acceptable to add 10% or more of fiber, no improvement in bending strength can be expected and it is rather uneconomical. Furthermore, in addition to the above-mentioned materials, when producing the cured glass fiber reinforced cement according to the present invention, conventional water reducing agents are used, such as those containing β-naphthalene sulfonic acid formalin condensate as the main component. "Mighty 150" (manufactured by Kao Soap Co., Ltd., product name) is displayed. The amount used is 0.2 to 0.2 to cement composition A.
The applicable range is 3.0%. Further, a part of the cement composition A may be replaced with fly ash or slag. To produce the cured glass fiber-reinforced cement of the present invention, the cement composition A, glass fibers, and aggregate are kneaded and shaped according to a conventional mortar or concrete mixing method, or
Alternatively, the cement composition A may be kneaded in advance into a paste or mortar, and then mixed with fibers during spraying, or a dry spraying method may be used. Curing after forming is carried out in the same manner as for conventional mortar and concrete. The cement composition A used in the cured glass fiber-reinforced cement of the present invention is one that does not substantially contain f.CaO, and is less hydroxylated than conventional cement compositions of this type containing f.CaO. Calcium production can be further suppressed, and the coagulation time is longer. Therefore, sufficient working time and good workability can be obtained when producing a cured glass fiber-reinforced cement body, and clogging caused by curing in paste or mortar tanks and clogging in hoses are completely eliminated. Moreover, the glass fiber reinforced cement hardened body based on the present invention has a feature that the decrease in bending strength over a medium to long term is significantly less than that of GRC using ordinary Portland cement or the like. Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto.
Note that parts and percentages in the text are by weight unless otherwise specified. Manufacturing Example of Binder The raw materials shown in Table 1 were mixed in the proportions shown in Table 2, and each of the pulverized raw material combinations was fired in a test kiln at 1200°C to 1350°C, and three types of clinker (No. 1 to 3) was obtained. profit

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Claims (1)

[Claims] 1 The main components are 18 to 70% by weight of calcium sulfoaluminate (C ₃ A ₃ C), 35% by weight or less of calcium sulfate (C), and 10 to 65% by weight of dicalcium silicate (C ₂ S) as binders, this house
SO ₃ is blended so that the SO ₃ / Al ₂ O ₃ molar ratio is 0.4 to 1.7, and the effective CaO is blended so that the effective CaO / Al ₂ O ₃ molar ratio is 0.5 to 1.2, so that no f・CaO remains. 1. A method for producing a hardened glass fiber-reinforced cement product, which comprises kneading and molding a cement composition obtained by mixing the cement composition with glass fibers, aggregate, and water.