JP2017186186A - Geopolymer composition, and geopolymer cured body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a geopolymer composition which can reduce the curing shrinkage.SOLUTION: A geopolymer composition comprises alkali silicate, an activation component which enables production of a geopolymer with the alkali silicate, and pulp fiber.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a geopolymer composition and a geopolymer cured body, and particularly relates to a geopolymer composition suitable for an architectural, civil engineering, or structure molding material, and a geopolymer cured body.

  Conventionally, building materials using cement have been provided. This building material is produced by utilizing a neutralization reaction between silicon dioxide and calcium hydroxide in cement. When the building material thus obtained is exposed in an outdoor environment, for example, rain containing carbon dioxide may corrode the building material over time and reduce the strength of the building material. Can be considered.

  Calcium oxide, which is a precursor of calcium hydroxide, is obtained by firing limestone containing calcium carbonate as a main component. When calcium oxide is thus obtained from limestone, carbon dioxide is also generated at the same time. For this reason, firing limestone may increase the carbon dioxide concentration in the atmosphere.

  Therefore, as an alternative to concrete and mortar, Patent Document 1 discloses a geopolymer containing a filler such as fly ash and an alkali activator containing at least one of potassium hydroxide, sodium hydroxide, sodium silicate, and potassium silicate. Compositions have been proposed.

  However, when the geopolymer composition is cured, the curing shrinkage tends to be larger than that of concrete or mortar. For this reason, it is considered that even a geopolymer composition such as Patent Document 1 causes a large shrinkage in curing, and it is difficult to make a cured product to a desired size immediately after the geopolymer composition is cured. there were.

JP 2008-239446 A

  The present invention has been made in view of the above points, and an object thereof is to provide a geopolymer composition capable of reducing cure shrinkage, and a geopolymer cured product that is a cured product of the geopolymer composition. And

  The geopolymer composition according to the present invention comprises an alkali silicate salt, an activating component that enables formation of a geopolymer with the alkali silicate salt, and pulp fibers.

  The geopolymer composition according to the present invention may contain the pulp fiber at a solid content weight ratio of 0.5 wt% or more and less than 2.0 wt%.

  The geopolymer cured product according to the present invention is a cured product of the geopolymer composition.

  ADVANTAGE OF THE INVENTION According to this invention, the geopolymer composition which can reduce cure shrinkage and the geopolymer hardened | cured material which is a hardened | cured material of the said geopolymer composition can be obtained.

  Hereinafter, an embodiment according to the present invention will be described.

  The geopolymer composition according to the present embodiment contains an alkali silicate salt, an activating component that enables formation of a geopolymer with the alkali silicate salt, and pulp fibers.

  When the geopolymer composition contains pulp fibers, it is possible to reduce curing shrinkage at the time of curing as compared with a composition not containing pulp fibers.

  When the geopolymer composition according to the present embodiment contains an alkali silicate salt and an activating component, a geopolymer can be generated. In this case, a geopolymer hardened | cured material can be obtained by advancing the production | generation of a geopolymer in a geopolymer composition. Here, the “geopolymer” is a silicic acid polymer containing aluminum or the like.

  On the other hand, as a cured product having an appearance similar to that of a geopolymer cured product, for example, a cement-based cured product is exemplified. This cement-based cured body is a cured product obtained by a neutralization reaction in its main components (for example, silicic acid and slaked lime).

  Since the geopolymer cured product is obtained by a reaction mechanism different from the neutralization reaction, it is less likely to be corroded by rain containing carbon dioxide or the like than the cement-based cured product.

  If the geopolymer composition contains a dry activated component and a dry alkali silicate salt, the geopolymer composition can contain water prior to curing. Thereby, the activating component and the alkali silicate can be dissolved in water to form a geopolymer.

  Specifically, the silicic acid alkali salt dissolved in water can be a silicic acid having a hydroxyl group, generally known as water glass. Since such water glass (silicic acid having a hydroxyl group) exhibits alkalinity, the geopolymer composition changes to an alkaline environment due to the formation of water glass. Thereby, it is considered that a part of the metal element contained in the activating component is eluted and the eluted metal element is formed in the metal hydroxide. It is considered that the water glass thus obtained reacts with the metal hydroxide to produce a geopolymer.

  The alkali silicate salt may be a compound containing silicic acid containing silicon as a main element and an alkali metal. Examples of the alkali silicate salt include sodium silicate, potassium silicate, and sodium metasilicate.

  When the geopolymer composition contains water glass, the geopolymer composition can contain water together with an alkali silicate salt. As water glass, sodium silicate aqueous solution and potassium silicate aqueous solution are mentioned, for example.

  The activating component may be a compound containing a metal element that becomes a metal hydroxide in an alkaline environment. The activation component can contain at least one component selected from the group of fly ash, slag and metakaolin. In view of convenience and cost when producing the geopolymer composition, the activation component preferably contains fly ash. When the activation component contains slag, the slag may be blast furnace granulated slag. An example of the metal element contained in the activation component is aluminum. If the geopolymer can be obtained from the activating component and the alkali silicate salt, the activating component may contain a metal element other than aluminum.

  When the activating component contains slag and fly ash, the weight ratio of slag to fly ash is preferably 100 to 10: 0 to 90, more preferably 50 to 30:50 to 70, particularly Preferably it is 40:60.

  When water glass is formed with water and an alkali silicate salt, a metal element may be eluted from the activation component into water contained in the water glass to form a metal hydroxide. This metal hydroxide and water glass (silicic acid having a hydroxyl group) react to form a geopolymer.

  The pulp fiber may be a fiber component mainly composed of cellulose. The pulp fiber can contain, for example, at least one selected from the group of interleaf pulp and waste paper pulp. The pulp fiber preferably has a freeness of 500 ± 100 ml as measured by a freeness test method based on JIS P 8121.

  The average fiber length of the pulp fibers is preferably 2.3 mm or more. The average fiber length of the pulp fiber can be measured by, for example, a sieving test.

  The geopolymer composition preferably contains pulp fibers in the range of 0.5 wt% or more and less than 2.0 wt% in terms of the solid content weight ratio. The lower limit of the preferable content of the pulp fiber is 0.5% by weight as described above, but is not limited thereto, and the content of the pulp fiber is more preferably 1% by weight or more. When the geopolymer composition contains 0.5% by weight or more of pulp fibers, curing shrinkage can be reduced depending on the content of pulp fibers. Further, when the geopolymer composition contains 2.0% by weight or more of pulp fibers, there is a tendency to increase the curing shrinkage at the time of subsequent dry curing even though the curing shrinkage at the curing curing can be reduced. Furthermore, when the geopolymer composition contains water, the water tends to be deficient as the pulp fiber content increases. For this reason, it may become difficult to disperse | distribute pulp fiber uniformly in a geopolymer composition. However, if the water content is increased in order to improve the dispersibility of the pulp fibers in the geopolymer composition, physical properties such as strength in the geopolymer cured product may be lowered.

  When the geopolymer composition contains pulp fibers, the geopolymer composition can contain a mixture of water and pulp fibers. In this case, it is preferable that the pulp fibers are uniformly dispersed in the mixed solution. When the geopolymer composition contains such a dispersion, pulp fibers can be uniformly dispersed in the geopolymer composition, and variations in curing shrinkage in the geopolymer cured product can be reduced.

  The geopolymer composition may contain an aqueous alkaline solution. In this case, while water glass can be produced | generated with alkali aqueous solution and silicic acid alkali salt, alkali aqueous solution can maintain an alkaline environment and can make it difficult to neutralize water glass in a geopolymer composition. Furthermore, it becomes possible to produce water glass from silicon oxides other than alkali silicates in an alkaline environment. Thereby, the production amount of a geopolymer increases, and the strength of the geopolymer cured product can be further improved. Examples of the alkaline aqueous solution include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.

  The amount of water contained in the geopolymer composition may be appropriately set according to the fluidity and convenience of the geopolymer composition as long as the effect according to the present embodiment can be obtained.

  The geopolymer composition is preferably a composition suitable for use in construction, civil engineering, and structure molding, and more preferably a composition suitable for a floor board material described later. In addition to the above applications, the geopolymer composition can be applied to applications in which concrete or mortar is generally employed.

  Depending on the use of the geopolymer composition, the geopolymer composition can contain various additives such as lightening materials, aggregates, reinforcing fibers, thickeners, colorants, and the like. The amount can be adjusted as appropriate. The content of the additive may be, for example, in the range of 0% by weight to 2.0% by weight in terms of the solid content weight ratio of the geopolymer composition.

  Examples of the weight reducing material include inorganic foams such as pearlite and shirasu balloon, and organic foams such as foamed polystyrene, polyvinylidene chloride foam, and acrylonitrile foam.

  Examples of the aggregate include mica, silica, silica powder, rock powder, silica sand, and crushed stone. When the aggregate is mica, the particle shape is scaly. For this reason, it is considered that mica functions as a filler and contributes to reducing the curing shrinkage of the geopolymer composition.

  The geopolymer composition may further contain reinforcing fibers other than the pulp fibers. Thereby, the reinforcing fiber is expected to reduce the curing shrinkage of the geopolymer composition and to improve the strength of the geopolymer cured product. Examples of reinforcing fibers include vinylon fibers, polypropylene fibers, acrylic fibers, carbon fibers, hemp, and metal fibers. More specifically, the reinforcing fiber may be a vinylon fiber.

  When the geopolymer composition is reinforced, curing shrinkage when obtaining a geopolymer cured product can be reduced.

  Examples of the thickener include methyl cellulose, hydroxymethyl cellulose, and carboxymethyl cellulose.

  Examples of the colorant include iron black, carbon black, and chromium oxide.

  The cured product of the geopolymer composition according to this embodiment is preferably a geopolymer cured product. When producing a geopolymer hardened | cured material, if a geopolymer composition can be hardened in a well-known procedure, the method of hardening a geopolymer composition will not be specifically limited. For example, the geopolymer composition can be filled into a mold. The geopolymer composition filled in the mold can be cured and cured to produce a cured cured product, and then the cured cured product can be dried. Thereby, the geopolymer composition can be obtained by curing the geopolymer composition in the mold and having an outer shape that matches the inner shape of the mold.

  The geopolymer cured body cured in the mold can be a material suitable for a floor board material such as an OA floor material. When the geopolymer cured body is used as the OA floor material, the geopolymer cured body does not have to be released from the mold.

  When producing a geopolymer cured product from a geopolymer composition, it is preferable to cure and cure the geopolymer composition at 60 ° C. and in a sealed state for 24 hours. The cured cured product is dried at 60 to 105 ° C. It is preferable to apply. In this case, it is possible to sufficiently generate the geopolymer. Thereby, the intensity | strength of a geopolymer hardened | cured material can be raised.

  When the geopolymer cured product is produced from the geopolymer composition, it is preferable that the alkali silicate salt, the activating component, and the pulp fiber are uniformly dispersed in the geopolymer composition before curing. In dispersing each component in the geopolymer composition, for example, the geopolymer composition can be kneaded in a batch type or continuous type mixer.

  In addition to the above, a geopolymer composition can be applied instead of cement or mortar. For example, when a geopolymer composition is filled in a gap in a structure such as stone, and cured, the geopolymer composition can function as an adhesive for the structure.

  When the geopolymer composition according to this embodiment is cured as described above, a geopolymer cured product having a reduced curing shrinkage can be obtained as compared with a geopolymer composition that does not contain pulp fibers.

  When a geopolymer composition containing no pulp fiber is cured in a mold, the volume of the resulting cured product tends to be smaller than the volume of the mold. This is believed to be due to the curing shrinkage of the geopolymer that occurs when the geopolymer composition is cured. For this reason, when hardening the geopolymer composition which does not contain a pulp fiber, it is necessary to predict the volume of the hardening body and to set the volume of a formwork appropriately.

  When the geopolymer composition of this embodiment contains pulp fibers, it is possible to reduce curing shrinkage when producing a geopolymer cured product from the geopolymer composition. Furthermore, due to the geopolymer generated when the geopolymer composition is cured, the geopolymer cured body is less likely to be corroded by rain containing carbon dioxide or the like than a cured product of cement or mortar.

  Hereinafter, the present invention will be specifically described by way of examples.

A geopolymer composition was prepared using the following components listed as specific examples.
・ Slag: Granulated blast furnace slag (Esment made by Nippon Steel & Sumikin Slag Products Co., Ltd.);
・ Fly ash: Chubu fly ash made by Techno Chubu Co., Ltd .;
Pulp fiber: 61.0% by weight of a mixture of pulp fiber (average fiber length 2.3 mm or more) containing interleaf pulp and waste paper pulp and water, freeness 500 ± 100 ml;
-Vinylon fiber: Vinylon fiber (2 dtex x 6 mm) manufactured by Kuraray Co., Ltd .;
・ Mica: Mica manufactured by Tokai Industry Co., Ltd .;
-Sodium silicate: Special No. 1 sodium silicate (water glass, 47% by weight aqueous solution) manufactured by Osaka Silicate Soda Co., Ltd.

<Example 1>
34.2 wt% slag, 51.2 wt% fly ash, 1.1 wt% vinylon fiber, 0.5 wt% pulp fiber, and 2.0 wt% solids by weight Of mica and 11.0% by weight of sodium silicate were put into the container to make the water content 30.0% by weight. And these components were mixed and the geopolymer composition was prepared. This geopolymer composition was filled in a mold, and the cured geopolymer composition was cured by curing at a temperature of 60 ° C. for 24 hours under a sealed condition. Subsequently, the cured cured product was dried at 60 ° C. to obtain a cured geopolymer.

<Example 2>
Example 1 was repeated except that 34.4% by weight of slag, 51.6% by weight of fly ash, 1.0% by weight of pulp fibers, and no vinylon fibers were added.

<Example 3>
The procedure was the same as Example 2 except that 34.2% by weight of slag, 51.3% by weight of fly ash, and 1.5% by weight of pulp fiber were used.

<Comparative Example 4>
Example 2 was repeated except that 34.0% by weight of slag, 51.0% by weight of fly ash, and 2.0% by weight of pulp fiber were used.

<Comparative Example 1>
Example 1 was repeated except that 34.4% by weight of slag and 51.5% by weight of fly ash were added and no pulp fiber was added.

  The composition in each example and comparative example is shown in Table 1 below.

  Using the cured cured product and the geopolymer cured product in each Example and Comparative Example, curing shrinkage during curing, curing shrinkage after drying, total shrinkage, water absorption, moisture content, and absolute The dry specific gravity was determined.

<Curing shrinkage during curing (curing shrinkage)>
After producing a cured cured product as described above from the geopolymer composition of each Example and Comparative Example, the curing shrinkage rate was calculated based on the following formula.
Curing shrinkage (%) = (B−A) / A × 100
The value A is an average value of values obtained by measuring the width and depth with a vernier caliper a plurality of times (three times) in a form having a square shape in plan view. The value B is an average value of values obtained by measuring the width and depth length several times (three times) with a caliper in the plan view shape of the cured cured product.

<Curing shrinkage after drying treatment (dry shrinkage)>
The cured cured products of each Example and Comparative Example were subjected to a drying treatment as described above to produce a cured geopolymer, and then the drying shrinkage was calculated based on the following formula.
Drying shrinkage (%) = (C−B) / B × 100
The value B is an average value of values obtained by measuring the width and depth length several times (three times) with a caliper in the plan view shape of the cured cured product. The above-mentioned value C is an average value of values obtained by measuring the width and depth with a vernier caliper a plurality of times (three times) in the plan view shape of the geopolymer cured body.

<Total shrinkage>
The value obtained as the sum of the curing shrinkage and the dry shrinkage calculated as described above was taken as the total shrinkage.

<Water absorption rate>
The geopolymer cured body of each Example and Comparative Example was immersed in water in a water bath for 24 hours, and its weight was measured. The weight thus measured was taken as the weight in the water absorption state. Moreover, the geopolymer hardened | cured material was dried at 105 degreeC for 24 hours, and the weight was measured. The weight thus measured was taken as the dry weight. The water absorption was calculated from the weight in the water absorption state and the weight in the dry state.

<Moisture content>
The initial weight of the geopolymer cured body of each Example and Comparative Example was measured, and then the geopolymer cured body was dried at 105 ° C. for 24 hours, and then the dry weight was measured. The water content was calculated from the initial weight and the dry weight.

<Absolute specific gravity>
The geopolymer cured bodies of each Example and Comparative Example were immersed in water in a water bath for 24 hours, and then the weight in water and the weight in a water absorption state were measured. Thereafter, the cured geopolymer was dried at 105 ° C. for 24 hours, and then the weight of the dried state was measured. The absolute dry specific gravity was calculated by dividing the weight in the dry state by the difference between the weight in the water absorption state and the weight in water. The weight in water was measured with a hanging scale.

  These results are shown in Table 2 below.

Claims (3)

  A geopolymer composition comprising an alkali silicate salt, an activating component capable of forming a geopolymer with the alkali silicate salt, and pulp fibers.   The geopolymer composition according to claim 1, wherein the pulp fiber is contained at a solid content weight ratio of 0.5 wt% or more and less than 2.0 wt%.   A geopolymer cured product, which is a cured product of the geopolymer composition according to claim 1.