JP2007161546A - Cement composition, hardening method of cement composition, and cement hardened material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement hardened material having high bending strength. <P>SOLUTION: The cement composition is obtained by mixing and kneading alumina cement, water glass, and water. The water glass as a solid component (S) is mixed with the alumina cement (C) in a ratio S/C of 10-80%. The bending strength of such a cement composition reaches 25 N/mm<SP>2</SP>or higher, and high bending strength that can not be obtained by a hardened material of the conventional portland cement is obtained. Also at the time of curing, it can be cured by heating it in a dry air and generation of steam is unnecessary. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a technique related to a cement composition, and is particularly effective when applied to a cement cured product having an alumina cement and water glass and extremely high bending strength.

  Various compositions have been disclosed for cement compositions. It has been pointed out that a hardened cement made from such a cement composition has a high compressive strength but a sufficient bending strength cannot be obtained.

In general, a hardened Portland cement cement widely used for concrete or mortar has a material strength of 28 days and a compressive strength of about 37 N / mm ² . However, the bending strength is only a very weak value of about 7 N / mm ² . Considering this point, the allowable stress of the concrete member is also defined as 1/10 of the compressive stress with respect to the bending stress.

  On the other hand, as a cement composition having water glass as its component, for example, Patent Document 1 discloses the disclosure. The structure which added alcohol in order to prevent the drying shrinkage | contraction is disclosed by the water glass concrete which provides acid resistance.

Further, Patent Document 2 discloses the use of water glass as one option of the alkali silicate solution when the inorganic composite contains the binder A composed of an alkali silicate solution, metal silicon or an alloy thereof, and cement. ing.
JP 2002-274927 A Japanese Patent Application Laid-Open No. 11-302065

  The present inventor wanted to significantly improve the bending strength in the conventional hardened cement material.

  If such bending strength can be improved, new demand for hardened cement can be expected in places where high bending strength is required.

  In addition, it is possible to reduce the thickness of the material even if the concrete using the hardened cement material so far does not provide sufficient bending strength, and even if the material thickness is increased, it is possible to reduce the material thickness. Can be done together.

  The objective of this invention is providing the technique of the cement hardened | cured material which has high bending strength.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  The cement composition of the present invention is characterized by comprising only alumina cement, water glass, and water. In this configuration, the weight ratio (S / C) of the solid content of the water glass to the alumina cement is 10% or more and 80% or less. Moreover, this invention is a cement composition characterized by including the solid content of water glass in the range of 10% or more and 80% or less by a weight ratio (S / C) with respect to an alumina cement.

  The present invention is a curing method for curing a cement composition comprising alumina cement, water glass, and water, wherein the cement composition is held in a water vapor pressure atmosphere less than a saturated water vapor pressure. . The present invention is a curing method for curing a cement composition having alumina cement, water glass, and water, wherein the cement composition is heated in a water vapor pressure atmosphere less than a saturated water vapor pressure. . In this configuration, the heating temperature is 50 ° C. or higher and 250 ° C. or lower.

The cement cured product of the present invention is characterized in that the cement composition having any one of the above-described configurations is used. The cement cured product of the present invention is characterized by being cured by the method for curing a cement composition having any one of the above-described configurations. Such a hardened cement product is characterized in that the bending strength is 25 N / mm ² or more without using reinforcing fibers.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

According to the present invention, a bending strength of 25 N / mm ² or more can be realized by curing a cement composition of at least alumina cement, water glass, and water.

  Such a cured cement with high bending strength, unlike the conventional curing of cement cured products, can be done by heating in a water vapor pressure atmosphere less than the saturated water vapor pressure, for example, in dry air. Can also be planned.

  Hereinafter, embodiments of the present invention will be described in detail.

An object of the present invention is to provide a hardened cement material having a significantly higher bending strength than a hardened material of Portland cement used conventionally. According to the present invention, for example, bending strength, 25 N / mm ² or more, it is possible to provide a 32N / mm ² or more, or 44N / mm ² or more cement cured product having a very high flexural strength.

  Such a cement hardened material having a high bending strength can be produced from a cement composition having a very simple structure of alumina cement, water glass and water. In addition, the curing for curing can be performed very easily by heating in a steam pressure atmosphere lower than the saturated steam pressure, for example, in dry air, unlike the conventional steam curing. Can also be achieved.

  The cement composition of the present invention is composed of alumina cement, water glass, and water. Basically, only such components may be used. Of course, aggregates and other things can be mixed. What is necessary is just to determine the amount of mixing of this aggregate etc. suitably as needed.

  The alumina cement to be used is not particularly limited. That is, conventionally available alumina cement can be used. For example, Class B alumina cement No. 2 manufactured by Denki Kagaku Kogyo Co., Ltd. can be used.

  Also, the water glass need not be specifically limited, like the alumina cement. Commercially available products can be used. For example, in addition to JIS standards 1, 2, and 3, non-JIS products manufactured and sold by water glass manufacturers can also be used.

  The composition of the cement composition is such that the weight ratio (S / C) of the water glass solids to the alumina cement is 10% or more and 80% or less, and the alumina cement is 56% or more and 91% or less by weight, The water glass solid content is 9% by weight or more and 44% by weight or less, and both are blended so as to be 100% by weight. What is necessary is just to add about 15-30% of water with respect to the whole solid substance, and to mix and knead with a mixer etc. so that a cement composition may have required fluidity | liquidity, and to manufacture a cement composition.

  Further, when a mortar or concrete is produced by blending an aggregate with a cement composition, the amount of mixing of the aggregate and the amount of water may be appropriately determined as necessary.

  In the production of such a cement composition, basically, the smaller the amount of water used, the better. Therefore, the minimum required amount within the range in which the alumina cement is uniformly mixed may be used. However, in actuality, considering the workability such as pouring into a mold, the fluidity is adjusted within a range in which the work can be smoothly performed, so that a cement composition which is an appropriate paste-like mixture can be obtained. You can adjust the amount of.

  A production method for producing a cured product of a cement composition using the cement composition produced by such a method will be described below. In manufacturing, a different method from the conventional steam curing is adopted.

  As shown in FIG. 1, a kneaded cement composition is prepared in step S100. In step S110, the kneaded cement composition is put into a mold. What is necessary is just to shape | mold by driving in a suitable formwork. The molding method using such a formwork may be the same as before. The cement composition is left in the mold until strength necessary for demolding is developed, and demolded in step S200 in a state where the strength is developed.

  After demolding, in step S210, the atmosphere is held in a steam pressure atmosphere that does not reach the saturated steam pressure. For example, heating is performed in a temperature range of 50 ° C. or higher and 250 ° C. or lower in dry air. The time required for heating depends on the size of the member, but at least at 100 ° C. or more, it is about 15 minutes on average as shown in the following examples. Then, if it cools, it will be the completion of the hardened | cured material of a cement composition.

  In addition, at 50 degreeC, the time required for a heating needs about 8 hours. When the temperature required for heating is as low as less than 100 ° C., depending on the temperature, it has been confirmed that it may take a considerable amount of time to cure and develop the required bending strength. It was.

  In the case of heat curing of concrete members using ordinary Portland cement, heating with steam is often performed. However, in the case of the present invention, heating with steam is not preferable because it reduces the strength. It is good to heat in dry air below saturated water vapor pressure. Incidentally, dry air refers to air containing water vapor that does not reach the saturated water vapor pressure at the heated temperature.

  In addition to the above-described method of heating in dry air after demolding, there is a method of heat-curing in a state of being placed in a mold. That is, as shown in FIG. 1, the cement composition prepared in step S100 is placed in a mold in step S110. What is necessary is just to use "the formwork which can restrain a shape".

  In step S110, the cement composition is put in the mold, and immediately in step S300, the mold composition is held in a water vapor pressure atmosphere less than the saturated water vapor pressure. For example, it is cured by heating in dry air. What is necessary is just to heat at 50 degreeC or more and 250 degrees C or less, for example in the case of heat curing. The time required for heating is about 15 at 100 ° C. or higher, and about 8 hours at 50 ° C. Then, after cooling and removing the mold in step S310, the cemented product is completed.

The cured product of the cement composition of the present invention produced in this way is produced from a simple composition of only alumina cement, water glass, and water, and can exhibit sufficiently high bending strength. it can. It was confirmed that the bending strength of the cement composition thus produced exceeded at least 25 N / mm ² , for example. A cured product of the cement composition having such a high bending strength is not currently known.

As a material having high bending strength known so far, the bending strength is at most a level of 25 N / mm ² by including reinforcing fibers. In the present invention, it is possible to ensure a bending strength of at least 25 N / mm ² or more without adding such reinforcing fibers.

  The hardened cement material of the present invention can further contain an aggregate and can be used as concrete or mortar.

  By using concrete or mortar made of cement hardened material with high bending strength and making a precast concrete member, since bending strength is high, member dimensions and thickness can be reduced, and inexpensive members are provided. can do. Moreover, as a board used for a wall surface or the like, a high-quality and inexpensive board can be provided by increasing toughness by a method such as mixing of reinforcing fibers.

Example 1
In this example, the effect of the mixing weight ratio of alumina cement and water glass on the bending strength of the cured product of the cement composition was examined. Specimens were prepared by changing the mixing weight ratio of alumina cement and water glass, and a bending fracture test was performed on each specimen. The results are shown in Table 1.

  In the following description, the weight mixing ratio (weight ratio) of water glass to alumina cement is abbreviated as S / C (%).

  Six types of specimens were used for the bending fracture test. As shown in Table 1, Specimen 1 contains 44% by weight of a solid content of water glass with respect to 56% by weight of alumina cement, and S / C is 79%. Specimen 2 contains 37% by weight of water glass solid content with respect to 63% by weight of alumina cement, and S / C is 59%. Specimen 3 contains 23% by weight of a solid content of water glass with 77% by weight of alumina cement, and S / C is 30%.

  Specimen 4 contains 17% by weight of water glass solid content with respect to 83% by weight of alumina cement, and S / C is 20%. In the specimen 5, 13% by weight of the solid content of water glass is blended with 87% by weight of the alumina cement, and S / C is 15%. Specimen 6 contains 9% by weight of water glass solid content with respect to 91% by weight of alumina cement, and S / C is 10%.

  Moreover, as shown in Table 1, for example, in specimens 1 to 6, the water content is 14% by weight, 16% by weight, and 19% by weight with respect to 100% by weight of the solid content of the alumina cement and water glass. 22%, 25%, 29% by weight.

  In preparing the specimen, alumina cement No. 2 manufactured by Denki Kagaku Kogyo Co., Ltd. was used as the alumina cement, and Hayashi Chemicals Co., Ltd. was used as the water glass. Alumina cement, water glass (corresponding to solid content), and water were weighed and kneaded so that the mixing ratio of each specimen shown in Table 1 was obtained. In the measurement, water was added in consideration of the moisture in the water glass, and the total moisture was adjusted to the mixing ratio shown in Table 1.

  The cement composition thus kneaded was driven into a metal mold having a height of 2 mm, a width of 10 mm, and a length of 30 mm. The mold was placed in an electric furnace with the cement composition as it was, and heated at 150 ° C. for 15 minutes. The specimen removed from the mold taken out from the electric furnace was air-cooled and then subjected to a bending fracture test.

  The size of the specimen is a plate shape of width 10mm x length 30mm x height 2mm. As shown in Fig. 2, this is simply supported at intervals of 24mm, and a load is loaded at the center to conduct a bending fracture test. went.

From Table 1, it can be seen that the six types of specimens have a bending strength of 25 N / mm ² or more. Specimen 6 is 25 N / mm ^2, specimens 1 shows a 32N / mm ^2, also serves up piece 2-5 any 44N / mm ² or more flexural strength.

In the specimens having S / C of 15%, 20%, 30%, and 59%, at least the bending strength was 44 N / mm ² or more. S / C is 10%, with 79% of the specimens, remarkably when the bending strength is shown lower than ^{25N / mm 2, 32N / mm} 2 and 44N / mm ² values, still compared to a normal cement cured Shows high bending strength.

Accordingly, it is confirmed that when the S / C is 10% or more and 80% or less, the bending strength is 25 N / mm ² or more and a sufficient strength is exhibited. More preferably, when S / C is 15% or more and 59% or less, the bending strength is 44 N / mm ² or more.

  The inventor inferred that the bending strength of the specimen 6 was small because the water glass content was small and the amount of water glass necessary for sufficient curing was not spread over the alumina cement. On the other hand, the cause of the decrease in the bending strength of the specimen 1 is that, when viewed from the fracture surface, the amount of water glass is large, and the particle size of bubbles generated inside the specimen during the heat treatment increases, so that the bending strength is increased. I guessed it would decline.

(Example 2)
In this example, the influence of temperature during curing of the cured cement composition was examined.

  Five types of specimens were prepared using a cement composition having a S / C ratio of 20% in which the maximum bending strength was developed in Example 1, and each was cured at different temperatures in dry air. The bending strength was measured. In the same manner as in Example 1, the bending strength was measured by a destructive test in which a load was applied to the center of the specimen while the specimen was simply supported. The results are shown in Table 2.

  Specimens 7, 8, 9, 10, and 11 were mixed with 17% by weight of water glass solids based on 83% by weight of alumina cement, and water was added to 100% by weight of solids of alumina cement and water glass. 22% by weight is mixed and mixed, and S / C has the same composition of 20%. For these specimens 7, 8, 9, 10, and 11, the curing temperatures were 50 ° C., 100 ° C., 150 ° C., 200 ° C., and 250 ° C., respectively, and the dry air was applied over the same 15 minutes except for the specimen 7. Heat curing in. In the case of the specimen 7, heating took 8 hours.

  From Table 2, it can be seen that all of the specimens 7 to 11 have a sufficiently large bending strength. However, in the specimens 10 and 11, the specimens 10 and 11 themselves were slightly changed to yellow. Furthermore, it was also confirmed that excessive water glass solids ooze from the surface.

  Therefore, it is considered that the practical curing temperature range for expressing sufficient bending strength is preferably 100 ° C. or more and less than 200 ° C. at the present time. More preferably, the heating temperature is considered to be sufficient if it promotes the curing reaction. In that sense, it is considered that sufficiently effective curing can be achieved even at 100 ° C. or higher and 150 ° C. or lower.

  In curing the cement composition of the present invention, as described above, unlike the conventional curing of the cured cement, steam curing cannot be used. When heated with steam and cured, the cause is not known, but the bending strength decreases.

  In any case, it is sufficient that the heating temperature is a temperature that accelerates the curing reaction, and it is considered that 100 ° C. to 150 ° C. is good for a small specimen such as this experiment. When the molded product becomes large, it seems that measures such as increasing the temperature and increasing the heating time are required.

Further, when the test is performed at a temperature of less than 100 ° C., for example, as in the specimen 1, the result is that the bending strength is 44 N / mm ² even when heated over time or left at room temperature. It was confirmed that the above cured product was obtained. That is, in the present invention, at the moment, for example, seems to 25 N / mm ² or more, or 32N / mm ² or more, or in order to obtain a high flexural strength of 44N / mm ² or more, etc., not necessarily heat required It is. However, it can be said that heating is effective in curing in a practical time range.

  Therefore, in the experiment at the present time, there are cases where it cannot be said that the heating time is practical, but within the range of the purpose of obtaining the bending strength, from the result including the specimen 7 of the results in Table 2, 50 It can be said that the temperature may be not lower than 250 ° C and not higher than 250 ° C. In particular, if it can be cured at a low temperature of less than 100 ° C., it is expected that it will be effective in the future when organic fibers that are weak at high temperatures are used.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention can be used in fields where cement compositions such as civil engineering and construction are used.

It is a flowchart which shows the hardening method of the cement composition of this invention. It is explanatory drawing which shows the Example of the bending strength test in this invention.

Explanation of symbols

  Steps S100, S110, S200, S210, S300, S310

Claims (9)

  A cement composition comprising only alumina cement, water glass, and water. The cement composition according to claim 1, wherein
The cement composition, wherein a weight ratio (S / C) of the solid content of the water glass to the alumina cement is 10% or more and 80% or less.   A cement composition comprising a solid content of water glass in a weight ratio (S / C) of 10% or more and 80% or less with respect to alumina cement. A curing method for curing a cement composition comprising alumina cement, water glass and water,
A method for curing a cement composition, comprising maintaining the cement composition in a water vapor pressure atmosphere less than a saturated water vapor pressure. A curing method for curing a cement composition comprising alumina cement, water glass and water,
A method for curing a cement composition, comprising heating the cement composition in a water vapor pressure atmosphere less than a saturated water vapor pressure. In the hardening method of the cement composition according to claim 5,
The method for curing a cement composition, wherein a temperature during the heating is 50 ° C or higher and 250 ° C or lower.   A cement cured product, wherein the cement composition according to any one of claims 1 to 3 is used.   A hardened cement material cured by the method for curing a cement composition according to any one of claims 4 to 6. The hardened cement material according to claim 7 or 8,
A hardened cement material having a bending strength of 25 N / mm ² or more without using reinforcing fibers.

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