Geopolymer composition and geopolymer hardened body

Abstract

To provide a geopolymer composition which hardly causes both self-shrinkage and drying shrinkage.SOLUTION: Provided is a geopolymer composition including an aluminosilicate compound, an alkali metal compound, an ether-based compound, and an aggregate, in which the alkali metal compound is at least one selected from the group consisting of an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal silicate, the ether-based compound is an alkylene oxide adduct of a monohydric to decahydric alcohol having 3 to 15 carbon atoms, an average number of added moles of an alkylene oxide having 2 to 4 carbon atoms with respect to 1 mol of the alcohol is 1 to 50 mol, and 50 mol% or more of the entire alkylene oxide is propylene oxide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a geopolymer composition and a hardened product thereof. [Background technology]

[0002] Geopolymer is a general term for condensation polymers formed by the reaction of activated fillers such as fly ash with alkaline solutions. The Japan Concrete Institute's "JCI-TC-155A: Report of the Research Committee on the Application of Geopolymer Technology to the Construction Industry" defines it as "a material that does not use cement clinker, but is hardened using a raw material (activated filler) whose main component is amorphous aluminum silicate and at least one aqueous solution of alkali metal silicate, carbonate, or hydroxide (alkaline solution)." Geopolymers are attracting attention as a material that can reduce environmental impact because they can significantly reduce CO2 emissions compared to the production of regular concrete.

[0003] The hardening reaction of the geopolymer is thought to proceed when the above-mentioned active filler comes into contact with an alkaline solution, causing metal ions such as silicon and aluminum present in the active filler to dissolve as silicate ions and aluminate ions, resulting in a polycondensation reaction accompanied by dehydration.

[0004] In the manufacturing process of geopolymers, a certain period of curing is required to allow the curing reaction to proceed sufficiently. However, during this process, the geopolymer is susceptible to so-called "shrinkage distortion" due to autogenous shrinkage caused by volume changes due to the condensation polymerization reaction and the movement of water, as well as drying shrinkage caused by the evaporation of water. Shrinkage distortion can cause cracks in the cured product, so to prevent this, geopolymers are formulated with shrinkage-reducing agents, such as those described in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-202964 [Non-patent literature]

[0006] [Non-Patent Document 1] Japan Concrete Institute, Research Committee Report on the Application of Geopolymer Technology to the Construction Sector, JCI-TC-155A Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional shrinkage-reducing agents for geopolymers are not necessarily effective in reducing both autogenous shrinkage and drying shrinkage of geopolymers. Therefore, there is still room for improvement in terms of suppressing shrinkage strain in geopolymers and more reliably preventing cracks.

[0008] Therefore, there is a need to develop a geopolymer composition that is less susceptible to both autogenous shrinkage and drying shrinkage. [Means for solving the problem]

[0009] The geopolymer composition of the present invention comprises an aluminosilicate compound, an alkali metal compound, an ether-based compound, and an aggregate; the alkali metal compound is at least one selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates; the ether-based compound is an alkylene oxide adduct of a monohydric to decahydric alcohol having 3 to 15 carbon atoms, the average number of moles of alkylene oxide added per mole of the alcohol is 1 to 50 moles, and 50 mole % or more of the alkylene oxide is propylene oxide; It is characterized by:

[0010] According to this configuration, the inclusion of the ether-based compound enhances the effect of reducing both autogenous shrinkage and drying shrinkage.

[0011] In one embodiment of the geopolymer composition according to the present invention, the alcohol in the ether compound is preferably a dihydric to pentahydric alcohol.

[0012] This configuration makes it possible to further enhance the effect of reducing both autogenous shrinkage and drying shrinkage of the geopolymer.

[0013] The hardened geopolymer of the present invention is characterized in that it is a hardened body of the above-mentioned geopolymer composition.

[0014] According to this configuration, a geopolymer composition that is resistant to both autogenous shrinkage and drying shrinkage is used, making it possible to obtain a geopolymer hardened body that is resistant to cracking.

[0015] Further features and advantages of the present invention will become more apparent from the following description of illustrative and non-limiting embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0016] The geopolymer composition and hardened geopolymer according to the present invention are described below. The geopolymer composition contains a shrinkage-reducing agent for geopolymers (shrinkage-reducing agent), an aluminosilicate compound, an alkali metal compound, and an aggregate.

[0017] [Configuration of shrinkage reducing agent for geopolymer] The shrinkage reducing agent for geopolymers according to this embodiment is an alkylene oxide adduct of a mono- to decahydric alcohol having 3 to 15 carbon atoms, wherein the average number of moles of alkylene oxide added per mole of the alcohol is 1 to 50 moles, and 50 mol% or more of the alkylene oxide is propylene oxide. It is more desirable that the proportion of propylene oxide in the total alkylene oxide is 75 mol% or more.

[0018] (alcohol) The mono- to decahydric alcohol having 3 to 15 carbon atoms includes not only a linear alcohol but also a branched or cyclic alcohol when the number of carbon atoms is 3 or more. The alcohol may also contain an unsaturated double bond, and may have multiple hydroxy groups bonded to the same carbon atom.

[0019] Specific examples include glycerin (a trihydric alcohol having 3 carbon atoms), trimethylolpropane (a trihydric alcohol having 6 carbon atoms), diglycerin (a tetrahydric alcohol having 6 carbon atoms), pentaerythritol (a tetrahydric alcohol having 5 carbon atoms), propylene glycol (a dihydric alcohol having 3 carbon atoms), 1-propanol (a monohydric alcohol having 3 carbon atoms), sucrose (an octahydric alcohol having 12 carbon atoms), 2-ethylhexanol (a monohydric alcohol having 8 carbon atoms), 1-butanol (a monohydric alcohol having 4 carbon atoms), etc. Among these, dihydric to pentahydric alcohols such as glycerin (a trihydric alcohol having 3 carbon atoms), trimethylolpropane (a trihydric alcohol having 6 carbon atoms), diglycerin (a tetrahydric alcohol having 6 carbon atoms), pentaerythritol (a tetrahydric alcohol having 5 carbon atoms), and propylene glycol (a dihydric alcohol having 3 carbon atoms) are more preferred.

[0020] (Alkylene oxide) Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, and butylene oxide. When the average number of moles of alkylene oxide added is 2 or more, the alkylene oxide may be composed of the same kind of alkylene oxide or two or more kinds of alkylene oxides, and in the latter case, the addition form of different kinds of alkylene oxides may be block addition or random addition.

[0021] Examples of the ether-based compounds include: A compound in which 10 moles of propylene oxide are added to 1 mole of glycerin A compound in which 8 moles of propylene oxide are added to 1 mole of trimethylolpropane A compound in which 3 moles of ethylene oxide and 12 moles of propylene oxide are randomly added to 1 mole of diglycerin. A compound in which 8 moles of propylene oxide are added to 1 mole of pentaerythritol A compound in which 6 moles of propylene oxide are added to 1 mole of propylene glycol A compound in which 1 mole of ethylene oxide and 4 moles of propylene oxide are sequentially block-added to 1 mole of 1-propanol. A compound in which 8 moles of ethylene oxide and 24 moles of propylene oxide are sequentially block-added to 1 mole of sucrose. A compound in which 1 mole of ethylene oxide and 7 moles of propylene oxide are randomly added to 1 mole of 2-ethylhexanol. A compound in which 10 moles of ethylene oxide and 20 moles of propylene oxide are randomly added to 1 mole of glycerin. Examples include compounds in which 2 moles of ethylene oxide and 2 moles of propylene oxide are block-added to 1 mole of 1-butanol.

[0022] (Other ingredients) The shrinkage reducing agent according to the present embodiment may contain other components in addition to the ether-based compounds as necessary, such as, but not limited to, antioxidants such as dibutylhydroxytoluene, air-entraining agents such as anionic surfactants, antifoaming agents such as polyoxyalkylene alkyl ethers, preservatives such as isothiazoline compounds, rust inhibitors such as nitrites, dispersants such as polycarboxylic acid compounds, and diluents such as water.

[0023] [Method for preparing ether-based compounds] The ether-based compound according to this embodiment can be prepared by reacting an alcohol, an alkylene oxide, a catalyst, and other optional components as needed, using a known method. For example, a predetermined amount of alcohol and catalyst is added to a pressure vessel equipped with a stirrer, a pressure gauge, and a thermometer, and the temperature is raised to a predetermined temperature. Then, a predetermined amount of alkylene oxide is added to the system under a predetermined pressure over a predetermined time while maintaining the predetermined temperature, and the reaction is carried out at the predetermined temperature and for the predetermined time. Finally, the catalyst is removed to obtain the ether-based compound.

[0024] [Method for producing shrinkage reducing agent for geopolymer] The shrinkage reducing agent according to the present embodiment is not limited to the ether-based compound alone, and may contain other components in addition to the ether-based compound as necessary. In this case, the shrinkage reducing agent can be obtained by mixing the ether-based compound and the other optional components by a known method.

[0025] [Configuration of geopolymer composition and geopolymer hardened body] The geopolymer composition according to this embodiment contains an aluminosilicate compound, an alkali metal compound, the shrinkage reducing agent, and an aggregate. The hardened geopolymer is obtained by hardening the geopolymer composition.

[0026] (aluminosilicate compounds) The aluminosilicate compound (xM2O·yAl2O3·zSiO2·nH2O, where M is an alkali metal) according to this embodiment dissolves cations such as aluminum and silicon when it comes into contact with water containing an alkali metal compound, and acts as a supply source of these cations.

[0027] Materials containing an aluminosilicate compound as a main component are generally called active fillers. Examples of active fillers include fly ash, ground granulated blast furnace slag, metakaolin, silica fume, ground zeolite, biomass ash, ground granulated molten slag from refuse incineration ash, ground granulated molten slag from sewage sludge, volcanic ash, rice husk ash, fluidized bed coal ash, paper sludge incineration ash, and mixtures of at least two of these (including premixes).

[0028] Fly ash is primarily composed of silica (SiO2) and alumina (Al2O3), and is classified as type I to IV in JIS A 6201 based on its fineness and flow value ratio, but it is not limited to these and materials that do not conform to the JIS standards can also be used as geopolymer raw materials.

[0029] Ground granulated blast furnace slag is a by-product produced when refining iron in a blast furnace. Its main components are calcium oxide (CaO), silica (SiO2), and alumina (Al2O3), and it is standardized under JIS A 6206.

[0030] An example of an embodiment of the active filler is a mixture of fly ash and ground granulated blast furnace slag. Geopolymer compositions containing fly ash tend to have excellent fluidity and workability. Geopolymer compositions containing ground granulated blast furnace slag tend to have high compressive strength in their hardened bodies. By mixing fly ash and ground granulated blast furnace slag, a hardened geopolymer body with a good balance of fluidity, workability, and mechanical strength can be obtained.

[0031] (alkali metal compounds) The alkali metal compound according to this embodiment is at least one selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates. Examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide. Examples of alkali metal carbonates include sodium carbonate and potassium carbonate. Examples of alkali metal silicates include sodium silicate (e.g., water glass), potassium silicate, and mixtures thereof. These alkali metal compounds may be used as an alkaline solution (aqueous solution of an alkali metal compound).

[0032] (aggregate) As the aggregate according to this embodiment, various known fine aggregates and coarse aggregates used in the production of geopolymers can be used. Examples of fine aggregates include river sand, mountain sand, land sand, sea sand, silica sand, crushed sand, crushed limestone sand, blast furnace slag fine aggregate, and recycled fine aggregate derived from waste concrete. Examples of coarse aggregates include crushed stone such as andesite, rhyolite, hard sandstone, and limestone, river gravel, mountain gravel, land gravel, blast furnace slag coarse aggregate, and recycled coarse aggregate derived from waste concrete.

[0033] (Other ingredients) The geopolymer composition according to this embodiment may contain other components as needed, in addition to the above-mentioned aluminosilicate compounds, alkali metal compounds, ether compounds, and aggregates. Examples of such other components include, but are not limited to, water, air entraining agents, antifoaming agents, dispersants, and setting modifiers.

[0034] [Method of manufacturing geopolymer composition] The geopolymer composition according to this embodiment is obtained by mixing the above-mentioned materials. The mixing of the materials is carried out, for example, by kneading using a mixer. The order in which the materials are mixed when preparing the geopolymer composition is not particularly limited. For example, the active filler and aggregate are first mixed, then an alkaline solution (aqueous solution of an alkali metal compound) is added and kneaded, and then a shrinkage reducing agent is added and kneaded. The geopolymer composition can be produced by this method.

[0035] The mixing ratio of the active filler, aggregate, alkaline solution, and shrinkage-reducing agent is not particularly limited, but for example, it is recommended to mix 100 parts by mass of the active filler with 200 to 600 parts by mass of aggregate, 30 to 70 parts by mass of alkaline solution (concentration 30% by mass), and 0.5 to 10 parts by mass of shrinkage-reducing agent.

[0036] [Method of manufacturing hardened geopolymer] A hardened geopolymer body can be obtained by, for example, pouring a geopolymer composition into a predetermined formwork and hardening it. The geopolymer composition poured into the formwork may be subjected to treatments such as degassing in a conventional manner. The geopolymer composition poured into the formwork generally hardens to form a hardened body by a condensation polymerization reaction accompanied by dehydration. The curing conditions for the geopolymer composition are not particularly limited, but it can be cured, for example, at room temperature to 80°C under conditions such as air curing, sealed curing, underwater curing, or (steam) heat curing.

[0037] Other Embodiments Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. [Example]

[0038] The present invention will be further described below with reference to examples. Note that the following examples do not limit the present invention. In the following examples and comparative examples, "parts" means parts by mass and "%" means % by mass unless otherwise specified.

[0039] [Preparation of Ether Compounds (Shrinkage Reducers)] Ether compounds (SR-1 to 10 and sr-1 to 4) according to Examples 1 to 10 and Comparative Examples 1 to 5 shown in Table 3 below were obtained. Note that sr-5 of Comparative Example 5 in Table 1 is glycerin.

[0040] (Prepared ether compounds) SR-1: A compound in which 10 moles of propylene oxide are added to 1 mole of glycerin. SR-2: A compound obtained by adding 8 moles of propylene oxide to 1 mole of trimethylolpropane. SR-3: A compound in which 3 moles of ethylene oxide and 12 moles of propylene oxide are randomly added to 1 mole of diglycerin. SR-4: A compound obtained by adding 8 moles of propylene oxide to 1 mole of pentaerythritol. SR-5: A compound in which 6 moles of propylene oxide are added to 1 mole of propylene glycol. SR-6: A compound in which 1 mole of ethylene oxide and 4 moles of propylene oxide are sequentially block-added to 1 mole of 1-propanol. SR-7: A compound in which 8 moles of ethylene oxide and 24 moles of propylene oxide are block-added to 1 mole of sucrose. SR-8: A compound in which 1 mole of ethylene oxide and 7 moles of propylene oxide are randomly added to 1 mole of 2-ethylhexanol. SR-9: A compound in which 10 moles of ethylene oxide and 20 moles of propylene oxide are randomly added to 1 mole of glycerin. SR-10: A compound in which 2 moles of ethylene oxide and 2 moles of propylene oxide are sequentially block-added to 1 mole of 1-butanol. SR-1: A compound obtained by adding 5 moles of ethylene oxide to 1 mole of 1-dodecanol SR-2: A compound in which 5 moles of ethylene oxide and 2 moles of propylene oxide are randomly added to 1 mole of 1-butanol. SR-3: Compound obtained by adding 2 moles of ethylene oxide to 1 mole of methanol SR-4: A compound obtained by adding 3 moles of propylene oxide to 1 mole of methanol and methyl etherifying the terminal hydroxyl group.

[0041] (Method for preparing ether-based compounds) SR-1: In a pressure vessel equipped with a stirrer, pressure gauge, and thermometer, 120.0 g (1.3 mol) of glycerin and 0.9 g of potassium hydroxide as a catalyst were added. The reaction system was then heated to 120°C. Subsequently, 756.8 g (13 mol) of propylene oxide was added to the reaction system over 3 hours at a gauge pressure of 0.4 MPa while maintaining the temperature at 130±5°C. The reaction was then held at the reaction temperature (130±5°C) for 1 hour to terminate the reaction. The catalyst was then removed to obtain the ether compound (SR-1).

[0042] SR-2, 4, 5, SR-1, SR-3: Produced in the same manner as SR-1, except that the type of alcohol and the amounts of alcohol, alkylene oxide, and catalyst used were changed.

[0043] SR-3: In a pressure vessel equipped with a stirrer, pressure gauge, and thermometer, 140.0 g (0.8 mol) of diglycerin and 0.8 g of potassium hydroxide as a catalyst were added. The reaction system was then heated to 120°C. Subsequently, while maintaining the temperature at 130±5°C, 111.3 g (2.5 mol) of ethylene oxide and 587.2 g (10.1 mol) of propylene oxide were simultaneously added to the reaction system at a gauge pressure of 0.4 MPa over a period of 3 hours. The reaction temperature (130±5°C) was then maintained for 1 hour to terminate the reaction. The catalyst was then removed to obtain the ether compound (SR-3).

[0044] SR-8, SR-9, SR-2: Produced in the same manner as SR-3, except that the type of alcohol and the amounts of alcohol, alkylene oxide, and catalyst used were changed.

[0045] SR-6: In a pressure vessel equipped with a stirrer, pressure gauge, and thermometer, 150.0 g (2.5 mol) of 1-propanol and 0.8 g of potassium hydroxide as a catalyst were added. The reaction system was then heated to 120°C. Subsequently, 110.0 g (2.5 mol) of ethylene oxide was added to the reaction system over 2 hours at a gauge pressure of 0.4 MPa while maintaining the temperature at 130±5°C. After maintaining the same temperature for 1 hour, 579.9 g (10.0 mol) of propylene oxide was added over 3 hours at a gauge pressure of 0.4 MPa. The reaction was then maintained at the same temperature for 1 hour to terminate the reaction. The catalyst was then removed to obtain the ether compound (SR-6).

[0046] SR-7 and SR-10: Produced in the same manner as SR-6, except that the type of alcohol and the amounts of alcohol, alkylene oxide, and catalyst used were changed.

[0047] SR-4: 100 g (3.1 mol) of methanol and 0.7 g of potassium hydroxide as a catalyst were added to a pressure vessel equipped with a stirrer, pressure gauge, and thermometer. The reaction system was then heated to 120°C. Subsequently, 412.5 g (9.4 mol) of ethylene oxide was added to the reaction system over a period of 3 hours at a gauge pressure of 0.4 MPa while maintaining the temperature at 130±5°C. The reaction was then held at the reaction temperature (130±5°C) for 1 hour to terminate the reaction. The mixture was then cooled to room temperature, and 236.4 g of methyl chloride was added, followed by a reaction at 120°C for 2 hours. After the reaction was completed, the temperature in the system was cooled to 60°C and the mixture was filtered to obtain the ether compound (SR-4).

[0048] [Production of geopolymer composition] (material) As a material for producing geopolymer compositions, Alkaline solution (GP): an aqueous solution containing alkali metal hydroxide and alkali metal silicate (GP solution (manufactured by Toso Sangyo Co., Ltd.)) (density 1.34 g / cm 3 ) Ether compounds (SR): The ether compounds (SR-1 to SR-10 and SR-1 to SR-4) of Examples 1 to 10 and Comparative Examples 1 to 4 prepared above, and glycerin (SR-5) (density 0.9 to 1.1 g / cm 3 ) Ground granulated blast furnace slag (GGBS): Esment 4000 (gypsum-free) (manufactured by Nippon Steel Blast Furnace Slag Cement Co., Ltd.) (density 2.91 g / cm 3 ) Fly ash (FA): Type II fly ash (manufactured by Chubu Fly Ash Co., Ltd.) (density 2.39 g / cm 3 ) Fine aggregate (S): Oigawa water system land sand (density 2.6g / cm 3 ) Coarse aggregate (G): Okazaki crushed stone (density 2.66 g / cm 3 ) Antifoaming agent: AFK-2 (Takemoto Oil Co., Ltd.) was used.

[0049] In this example, both ground granulated blast furnace slag (GGBS) and fly ash (FA) were used as the aluminosilicate compound (B). An antifoaming agent was added in an amount of 0.005% relative to the aluminosilicate compound (B) so that the air content was 2% or less.

[0050] The blending ratio of the above materials is shown in Table 1 below. [Table 1]

[0051] The above materials were kept at a temperature of 20°C ± 2°C for at least one day. Next, in a temperature-controlled room at 20°C and 80% humidity, ground granulated blast furnace slag (GGBS), fly ash (FA), fine aggregate (S), and coarse aggregate (G) were sequentially added to a pan-type mixer with a nominal capacity of 55 L according to the mixing conditions shown in Table 1, and then dry-mixed for 30 seconds.

[0052] Next, the alkaline solution (GP), ether compound or glycerin (SR), and antifoaming agent were added to the mixer and mixed for 150 seconds. This resulted in the preparation of the geopolymer composition. Immediately after mixing, the physical properties were measured and test specimens were collected.

[0053] [Measurement of physical properties of geopolymer composition] (1) Measurement of autogenous shrinkage In accordance with the Super-Fluidity Concrete Research Committee Report (II) [Appendix 1] (tentative title) Autogenous Shrinkage Test Method for High-Fluidity Concrete (May 1994, Japan Concrete Institute), an embedded strain gauge was embedded in the geopolymer composition to measure the autogenous shrinkage strain and evaluate the autogenous shrinkage performance. Measurements began immediately after filling the geopolymer composition. The test room was kept at a room temperature of 20±2°C and a humidity of 60%. The measured values ​​were used to calculate the autogenous shrinkage strain (autogenous shrinkage) according to the following formula: The results are shown in Table 3. Autogenous shrinkage strain = ε1-γΔT ε1: Strain obtained from the embedded strain gauge at age t days (strain value after temperature correction of the embedded strain gauge) γ: Thermal expansion coefficient of geopolymer (10 × 10 -6 / ℃) ΔT: Difference (°C) between the temperature of the specimen obtained from the thermocouple on day t and the temperature at which it was placed The results of autogenous shrinkage shown in Table 3 are the results of a test conducted over five days.

[0054] (2) Measurement of drying shrinkage Test specimens were prepared using the geopolymer composition immediately after mixing, and after sealing and curing for 5 days at 20±2°C and 60% humidity, they were demolded and their base lengths were measured. Measurements were then carried out in accordance with JIS A 1129-3 (2010) "Length change test method for mortar and concrete." Specimen: 100mm x 100mm x 400mm rectangular column specimen Test room: Room temperature 20±2℃, humidity 60% The length change rate ε (drying shrinkage) was calculated using the obtained measured values ​​based on the following formula. The results are shown in Table 3. Length change rate ε={(X 01 -X 02 )-(X i1 -X i2 )} / L0 L0:Kicho X 01 , X 02 : Measurement values ​​of the standard scale and specimen at the respective reference points X i1 , X i2 : Measurement values ​​of the standard scale and specimen at time i, respectively The drying shrinkage results shown in Table 3 are from a test period of 13 weeks. Because autogenous shrinkage continues to progress even after 5 days of age, the drying shrinkage values ​​include shrinkage due to autogenous shrinkage after 5 days of age.

[0055] (3) Slump flow measurement The geopolymer composition immediately after mixing was measured in accordance with JIS A 1150 (2020) "Test method for slump flow of concrete."

[0056] (4) Measurement of air volume The geopolymer composition immediately after mixing was measured in accordance with JIS A 1128 (2020) "Pressure test method for air content of fresh concrete - Air chamber pressure method."

[0057] Evaluation of Geopolymer Compositions For each of Examples 1 to 10 and Comparative Examples 1 to 6, the reduction rate (%) of autogenous shrinkage and drying shrinkage was calculated based on the following formula, and evaluated based on the criteria in Table 2. Reduction rate of autogenous shrinkage (%) = (autogenous shrinkage strain (μ) of Comparative Example 6 - autogenous shrinkage strain (μ) of each sample) / autogenous shrinkage strain (μ) of Comparative Example 6 × 100 Drying shrinkage reduction rate (%) = (length change rate (μ) of Comparative Example 6 - length change rate (μ) of each sample) / length change rate (μ) of Comparative Example 6 × 100 In both cases of autogenous shrinkage and drying shrinkage, the higher the reduction rate (%), the greater the reduction effect. The evaluation results are shown in Table 3. [Table 2] [Table 3] The amount added (Bx%) in Table 3 indicates the mass (%) relative to the total amount of the aluminosilicate compound (B).

[0058] As shown in the evaluation column of Table 3, the geopolymer compositions of the present invention (Examples 1 to 10) exhibit a reduction rate of at least 10% in autogenous shrinkage and at least 20% in drying shrinkage. [Industrial Applicability]

[0059] The present invention can be used to produce geopolymers.

Claims

1. A geopolymer composition comprising an aluminosilicate compound, an alkali metal compound, an ether-based compound, and an aggregate, the alkali metal compound is at least one selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates; The ether-based compound is an alkylene oxide adduct of a mono- to decahydric alcohol having 3 to 15 carbon atoms, and the average number of added moles of alkylene oxide having 2 to 4 carbon atoms per mole of the alcohol is 1 to 50 moles, and 50 mol% or more of the alkylene oxide in total is propylene oxide. A geopolymer composition characterized by this.

2. The geopolymer composition of claim 1, wherein the alcohol in the ether-based compound is a dihydric to pentahydric alcohol.

3. A hardened geopolymer, which is a hardened geopolymer composition according to claim 1 or 2.

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