JP7686466B2 - Geopolymer composition and hardened geopolymer - Google Patents

Description

The present disclosure relates to geopolymer compositions and hardened geopolymer bodies.

Patent Document 1 discloses a geopolymer shrinkage reducing agent that is an ester-based compound having an oxyalkylene group, and a geopolymer-forming composition and a geopolymer hardened body that contain the shrinkage reducing agent.

Patent Document 2 discloses a shrinkage reducing agent for geopolymers that is a glycol ether-based compound, and a geopolymer-forming composition and a geopolymer hardened body that contain the shrinkage reducing agent.

Patent Document 3 discloses an admixture for geopolymers that contains a shrinkage reducing agent that is an oxyalkylene alkyl ether compound and a shrinkage reducing assistant that is an aliphatic oxycarboxylic acid compound, and a geopolymer-forming composition and a geopolymer hardened body that contain the admixture.

Patent Document 4 discloses a geopolymer composition that includes an active filler containing fly ash and blast furnace slag, an alkaline solution containing sodium silicate and/or sodium hydroxide, and a cement mineral-based expanding material.

JP 2017-202963 A JP 2018-150195 A JP 2017-202964 A JP 2020-055696 A

It has been reported that hardened geopolymers are alkaline when they first harden and then become neutral, and it is believed that the neutralization of hardened geopolymers is due to carbonation.

The objective of the present disclosure is to provide a geopolymer composition that produces a hardened body with a slow neutralization rate, and a hardened geopolymer body that produces a hardened body with a slow neutralization rate.

Specific means for solving the above problems include the following aspects.
<1> An active filler, a base, water, a blast furnace slag fine aggregate, and at least one selected from the group consisting of an ester compound having an oxyalkylene group, an ether compound having an oxyalkylene group, and a glycol compound having an oxyalkylene group. A geopolymer composition comprising:
<2> The total content of the ester compound having an oxyalkylene group, the ether compound having an oxyalkylene group, and the glycol compound having an oxyalkylene group is 0.5% by mass to 5% by mass relative to the total amount of the active filler. The geopolymer composition described in <1>.
<3> The geopolymer composition according to <1> or <2>, wherein the active filler comprises at least one of fly ash and blast furnace slag powder.
<4> A geopolymer hardened body which is a hardened product of the geopolymer composition according to any one of <1> to <3>.

According to the present disclosure, a geopolymer composition having a slow neutralization rate of the resulting hardened body and a geopolymer hardened body having a slow neutralization rate are provided.

The following describes embodiments of the invention. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention.

In the present disclosure, the numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

<Geopolymer composition>
The geopolymer composition of the present disclosure is a composition in a state called a slurry, fresh, etc., and the geopolymer composition of the present disclosure hardens to obtain the geopolymer hardened body of the present disclosure.

The geopolymer composition of the present disclosure includes an active filler, a base, water, fine blast furnace slag aggregate, and at least one compound selected from the group consisting of an ester compound having an oxyalkylene group, an ether compound having an oxyalkylene group, and a glycol compound having an oxyalkylene group.

In this disclosure, ester compounds having an oxyalkylene group, ether compounds having an oxyalkylene group, and glycol compounds having an oxyalkylene group are collectively referred to as "chemical admixtures having an oxyalkylene group."

The inventors of the present disclosure have discovered that neutralization of the hardened body can be suppressed by replacing the fine aggregate of geopolymer mortar or geopolymer concrete from natural sand to blast furnace slag fine aggregate.
Without being bound by any particular theory, it is speculated that because the components contained in blast furnace slag fine aggregate exhibit similar reactivity to active fillers, the surface of the blast furnace slag fine aggregate becomes part of the geopolymer structure, resulting in stronger bonds between the blast furnace slag fine aggregate and the paste portion, and thus suppressing carbonation compared to when natural sand is used as the fine aggregate.

Furthermore, the inventors of the present disclosure have discovered that chemical admixtures having oxyalkylene groups have a carbonation inhibitory effect on the hardened geopolymer body. It has been known that chemical admixtures having oxyalkylene groups exhibit a shrinkage reducing effect in geopolymer mortar or geopolymer concrete (e.g., Patent Documents 1 and 2), but it has not been known that they exhibit a carbonation inhibitory effect in geopolymer mortar or geopolymer concrete.

The materials that make up the geopolymer composition of this disclosure are described in detail below.

[Active filler]
The active filler is generally an aluminum silicate based powder.
Examples of active fillers include fly ash, ground granulated blast furnace slag, metakaolin, silica fume, ground granulated zeolite, ground granulated waste incineration ash molten slag, ground granulated sewage sludge molten slag, volcanic ash, rice husk ash, fluidized bed coal ash, paper sludge incineration ash, and mixtures of at least two of these.

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

The quality of the FA (e.g., density, fineness), the quality of the BFS (e.g., density, fineness), and the mixing ratio of the FA and BFS are not limited, and may be selected depending on the target fluidity, workability, pot life, setting time, pore structure, mechanical strength, etc.
Examples of FA include types I, II, III, and IV as defined in JIS A6201:2015.
Examples of BFS include ground granulated blast furnace slag 3000, 4000, 6000, and 8000 as specified in JIS A6206:2013.

[Base and Water]
The base is also referred to in the art as an alkaline activator, an alkaline stimulant, and the like.
The base is generally at least one selected from the group consisting of alkali metal silicates, alkali metal carbonates, and alkali metal hydroxides.
Specific examples of the base include at least one selected from the group consisting of sodium silicate, potassium silicate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

When an alkali metal silicate is used as the base, it is believed that at least a portion of the silicon atoms contained in the base are incorporated into the geopolymer structure.
It is believed that at least a portion of the metal ions (eg, Na ⁺ , K ⁺ ) derived from the base are retained within the geopolymer structure.

Water is the site where the components and bases contained in the active filler are dissolved or ionized, and where the geopolymer structure is formed by a condensation polymerization reaction.

The base and water included in the geopolymer composition are generally derived from an alkaline solution, i.e., the base and water are included in the geopolymer composition by mixing the active filler with the alkaline solution.
In other words, a geopolymer composition comprising an active filler, a base, and water is a geopolymer composition obtained by mixing an active filler with an alkaline solution.

Specific examples of the alkaline solution used to form the geopolymer composition include sodium silicate solution (water glass of sodium silicate), potassium silicate solution (water glass of potassium silicate), aqueous sodium carbonate solution, aqueous potassium carbonate solution, aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, and a mixture of at least two of these. Water may also be mixed in order to ensure workability.

The type and concentration of the alkaline solution used to form the geopolymer composition may be selected based on the reactivity of the base to ensure pot life, mechanical strength after hardening, etc.

One example of an embodiment of an alkaline solution is a mixture of a sodium silicate solution (sodium silicate water glass) and an aqueous solution of sodium hydroxide.

[Fine blast furnace slag aggregate]
As the blast furnace slag fine aggregate, an article that complies with the standard of JIS A5011-1:2018 "Slag aggregate for concrete - Part 1: Blast furnace slag aggregate" is preferable.

Blast furnace slag fine aggregate can be classified, for example, by particle size, density, water absorption rate, or a combination of these, and the classification can be selected according to the target mechanical strength of the hardened geopolymer body.

The geopolymer composition of the present disclosure may contain other fine aggregates besides blast furnace slag fine aggregate.
In the geopolymer composition of the present disclosure, the mass ratio of blast furnace slag fine aggregate to the entire fine aggregate is, for example, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass.

[Other aggregates]
The geopolymer composition of the present disclosure may contain other aggregates other than blast furnace slag fine aggregate, including various fine and coarse aggregates conventionally used in geopolymer mortar or concrete or cement mortar or concrete.

Examples of fine aggregates other than blast furnace slag fine aggregate include river sand, mountain sand, land sand, sea sand, silica sand, crushed sand, crushed limestone sand, and recycled fine aggregate derived from waste concrete.
Examples of coarse aggregate 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 concrete waste.
The type and content of these aggregates may be selected depending on the target mechanical strength of the hardened geopolymer body.

[Chemical admixture having an oxyalkylene group]
Chemical admixtures having an oxyalkylene group (ester compounds having an oxyalkylene group, ether compounds having an oxyalkylene group, and glycol compounds having an oxyalkylene group) exhibit a neutralization inhibitory effect in hardened geopolymer bodies.

In the geopolymer composition of the present disclosure, the content of the chemical admixture having an oxyalkylene group is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, based on the total amount of the active filler, from the viewpoint of suppressing neutralization of the geopolymer hardened body.
In the geopolymer composition of the present disclosure, the content of the chemical admixture having an oxyalkylene group is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, based on the total amount of active filler, from the viewpoint of ensuring the compressive strength of the geopolymer hardened body.

Specific examples of chemical admixtures having an oxyalkylene group include the chemicals represented by the following formulas (1), (2), (3), (4), and (5).

Formula (1) R ¹ -C(═O)-O-(A ¹ O) _n1 -R ²

In formula (1), R ¹ is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, A ¹ O is a divalent alkylene oxide group having 2 to 4 carbon atoms, n1 is the average number of moles of alkylene oxide added and is a number from 1 to 200, R ² is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms or a -C(=O)-R ³ group, and R ³ is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms.

Formula (2) [HO-C(=O)-] _k R ⁴ [-C(=O)-O-(A ² O) _n2 -R ⁵ ] _m

In formula (2), R ⁴ is a residue resulting from removing (k+m) carboxy groups from a (k+m)-valent polyvalent carboxylic acid having 1 to 30 carbon atoms, or a single bond, k and m are integers satisfying the relationships 0≦k≦5, 1≦m≦6, and 2≦k+m≦6, A ² O is a divalent alkylene oxide group having 2 to 4 carbon atoms, n2 is the average number of moles of alkylene oxide added and is a number from 1 to 200, and R ⁵ is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 2 to 30 carbon atoms.
In ^R4 , the carbon atom of the carboxy group (-COOH) is not included in the number of carbon atoms of the polyvalent carboxylic acid.

Formula (3) [R ⁷ -(OA ³ ) _n3 -O-] _p R ⁶ [-OC(=O)-R ⁸ ] _q

In formula (3), R ⁶ is a residue obtained by removing (p+q) hydroxy groups from a (p+q)-valent polyhydric alcohol having 2 to 30 carbon atoms, R ⁷ is a hydrogen atom or a -O-C(=O)-R ⁹ group, OA ³ is a divalent oxyalkylene group having 2 to 4 carbon atoms, n3 is the average number of moles of oxyalkylene added and is a number from 1 to 200, R ⁸ is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, R ⁹ is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, and p and q are integers satisfying the relationships 1≦p≦7, 1≦q≦7, and 2≦p+q≦8.

Formula (4)
[H-(OA ⁴ ) _n4 -O-] _r R ¹⁰ [-O-(A ⁵ O) _n5 -C(=O)-R ¹¹ ] _s

In formula (4), R ¹⁰ is a residue obtained by removing (r+s) hydroxy groups from a (r+s)-valent polyhydric alcohol having 2 to 30 carbon atoms, OA ⁴ is a divalent oxyalkylene group having 2 to 4 carbon atoms, n4 is the average number of moles of oxyalkylene added and is a number from 1 to 200, R ¹¹ is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, A ⁵ O is a divalent alkylene oxide group having 2 to 4 carbon atoms, n5 is the average number of moles of alkylene oxide added and is a number from 1 to 200, and r and s are integers that satisfy the relationships 0≦r≦7, 1≦s≦8, and 2≦r+s≦8.

In the formulas (1) to (4), when R ¹ , R ² , R ³ , R ⁵ , R ⁸ , R ⁹ , and R ¹¹ are each an alkyl group having 1 to 30 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group, a heneicosyl group, a docosyl group, a tricosyl group, a tetracosyl group, a pentacosyl group, a hexacosyl group, a heptacosyl group, an octacosyl group, a nonacosyl group, or a triacontyl group, and the alkyl group having 3 or more carbon atoms may be linear, branched, or cyclic, or a combination thereof.

In formulas (1) to (4), R ¹ , R ² , R ³ , R ⁵ , R ⁸ , R ⁹ , and R When ¹¹ is an alkenyl group having 2 to 30 carbon atoms, it is, for example, an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, a nonadecenyl group, an eicosenyl group, a heneicosenyl group, a docosenyl group, a tricosenyl group, a tetracosenyl group, a pentacosenyl group, a hexacosenyl group, a heptacosenyl group, an octacosenyl group, a nonacosenyl group, or a triacontenyl group, and the alkenyl group having 3 or more carbon atoms may be linear, branched, cyclic, or a combination thereof.

In formula (1), formula (2), or formula (4), A ¹ O, A ² O, or A ⁵ O is a divalent alkylene oxide group having 2 to 4 carbon atoms, specifically, an ethylene oxide group, a propylene oxide group, or a butylene oxide group, respectively, and when it is a propylene oxide group or a butylene oxide group, it may be linear, branched, or cyclic.
When n1, n2, and n5 are each 2 or more, each of (A ¹ O) _n1 , (A ² O) _n2 , and (A ⁵ O) _n5 may be a chain of one type of alkylene oxide group, or a chain of two or more types of alkylene oxide groups, and the chain of two or more types of alkylene oxide groups may have a block structure or a random structure.

In formula (3) or formula (4), OA ³ and OA ⁴ are each a divalent oxyalkylene group having 2 to 4 carbon atoms, specifically, an oxyethylene group, an oxypropylene group, or an oxybutylene group, respectively, and when they are an oxypropylene group or an oxybutylene group, they may be linear, branched, or cyclic.
When n3 and n4 are each 2 or greater, ( ^OA3 ) _n3 and ( ^OA4 ) _n4 may each be a chain of one type of oxyalkylene group, or a chain of two or more types of oxyalkylene groups, and the chain of two or more types of oxyalkylene groups may have a block structure or a random structure.

The (k+m)-valent polycarboxylic acid having 1 to 30 carbon atoms in R ⁴ in formula (2) may be linear, branched, cyclic, or a combination thereof when it has 3 or more carbon atoms, and may contain an unsaturated double bond when it has 2 or more carbon atoms, and may have multiple carboxy groups bonded to the same carbon atom. The (k+m)-valent polycarboxylic acid having 1 to 30 carbon atoms is a polycarboxylic acid having 2 to 6 carboxy groups since 2≦k+m≦6, and examples thereof include aliphatic polycarboxylic acids (e.g., malonic acid, succinic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, glutaric acid, azelaic acid); aromatic polycarboxylic acids (e.g., terephthalic acid, isophthalic acid, orthophthalic acid, trimellitic acid, pyromellitic acid); and alicyclic polycarboxylic acids (e.g., cyclohexane 1,4-dicarboxylic acid). Among these, aliphatic polycarboxylic acids having 2 to 12 carbon atoms are preferred, and succinic acid, adipic acid, sebacic acid, maleic acid or fumaric acid is more preferred.

R ⁴ is preferably a (k+m) valent hydrocarbon group having 1 to 30 carbon atoms.

The (p+q)-valent polyhydric alcohol having 2 to 30 carbon atoms in R ⁶ in formula (3) may be linear, branched, cyclic, or a combination thereof when it has 3 or more carbon atoms, and may contain an unsaturated double bond when it has 2 or more carbon atoms, and may have multiple hydroxy groups bonded to the same carbon atom. The (p+q)-valent polyhydric alcohol having 2 to 30 carbon atoms is a polyhydric alcohol having 2 to 8 hydroxy groups since 2≦p+q≦8, and examples thereof include dihydric alcohols (e.g., ethylene glycol, diethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexanediol); trihydric to pentahydric polyhydric alcohols (e.g., glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitan, diglycerin); and sugars and derivatives thereof (e.g., sucrose, glucose, fructose, methyl glycoside). Among these, trihydric to pentahydric polyhydric alcohols or sugars are preferred, and sorbitol, sorbitan, polyglycerin, pentaerythritol, dipentaerythritol or sucrose are more preferred.

R ⁶ is preferably a (p+q)-valent hydrocarbon group having 2 to 30 carbon atoms, and the hydrocarbon group may contain an ether bond.

The (r+s)-valent polyhydric alcohol having 2 to 30 carbon atoms in R ¹⁰ in formula (4) may be linear, branched, cyclic, or a combination thereof when it has 3 or more carbon atoms, and may contain an unsaturated double bond when it has 2 or more carbon atoms, and may have multiple hydroxy groups bonded to the same carbon atom. The (r+s)-valent polyhydric alcohol having 2 to 30 carbon atoms is a polyhydric alcohol having 2 to 8 hydroxy groups since 2≦r+s≦8, and examples thereof include dihydric alcohols (e.g., ethylene glycol, diethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexanediol); trihydric to pentahydric polyhydric alcohols (e.g., glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitan, diglycerin); and sugars and derivatives thereof (e.g., sucrose, glucose, fructose, methyl glycoside). Among these, trihydric to pentahydric polyhydric alcohols or sugars are preferred, and sorbitol, sorbitan, polyglycerin, pentaerythritol, dipentaerythritol or sucrose are more preferred.

R ¹⁰ is preferably a hydrocarbon group having 2 to 30 carbon atoms and a valence of (r+s), and the hydrocarbon group may contain an ether bond.

Examples of the (k+m)-valent hydrocarbon group having 1 to 30 carbon atoms, the (p+q)-valent hydrocarbon group having 2 to 30 carbon atoms, and the (r+s)-valent hydrocarbon group having 2 to 30 carbon atoms include groups obtained by removing (k+m), (p+q), and (r+s) hydrogen atoms from an alkane having 1 to 30 carbon atoms or an alkene having 2 to 30 carbon atoms, respectively.
Examples of alkanes having 1 to 30 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, nonacosane, triacontane, and the like, and the structure may be linear, branched, or cyclic, or a combination thereof.
Examples of alkenes having 2 to 30 carbon atoms include ethene, propene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, octadecene, nonadecene, eicosene, heneicosene, docosene, tricosene, tetracosene, pentacosene, hexacosene, heptacosene, octacosene, nonacosene, triacontene, and the like, and the structure may be linear, branched, or cyclic, or a combination thereof.

Preferred examples of the chemical substance represented by formula (1) are given below.
R ¹ is an alkyl group having 1 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof) or an alkenyl group having 2 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof);
R ² is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms (linear, branched, cyclic, or a combination thereof), an alkenyl group having 2 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof), or a -C(=O)-R ³ group, and R ³ is an alkyl group having 1 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof);
A ¹ O is an ethylene oxide group or a propylene oxide group;
n1 is 1 to 100 or 1 to 50.

Preferred examples of the chemical substance represented by formula (2) are given below.
R ⁴ is a residue obtained by removing (k+m) carboxy groups from a (k+m)-valent polyvalent carboxylic acid having 2 to 10 carbon atoms, and is preferably a (k+m)-valent hydrocarbon group (linear, branched, cyclic, or a combination thereof) having 2 to 10 carbon atoms;
k is 0 or 1, m is 1 or 2,
R ⁵ is an alkyl group having 1 to 10 carbon atoms (linear, branched, cyclic, or a combination thereof);
A ² O is an ethylene oxide group or a propylene oxide group;
n2 is 1 to 100 or 1 to 50.

Preferred examples of the chemical substance represented by formula (3) are as follows.
R ⁶ is a residue obtained by removing (p+q) hydroxy groups from a (p+q)-valent polyhydric alcohol having 2 to 10 carbon atoms, and is preferably a (p+q)-valent hydrocarbon group having 2 to 10 carbon atoms (linear, branched, cyclic, or a combination thereof; the hydrocarbon group may contain an ether bond);
p and q satisfy the relationships of 1≦p≦4, 1≦q≦4, and 2≦p+q≦6;
^R7 is a hydrogen atom;
R ⁸ is an alkyl group having 1 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof) or an alkenyl group having 2 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof), preferably an alkyl group having 10 to 18 carbon atoms or an alkenyl group having 10 to 18 carbon atoms;
^OA3 is an oxyethylene group or an oxypropylene group;
n3 is 1 to 100, 1 to 80, or 5 to 80.

Preferred examples of the chemical substance represented by formula (4) are as follows.
R ¹⁰ is a residue obtained by removing (r+s) hydroxy groups from a (r+s)-valent polyhydric alcohol having 2 to 10 carbon atoms, and is preferably a (r+s)-valent hydrocarbon group having 2 to 10 carbon atoms (linear, branched, cyclic, or a combination thereof; the hydrocarbon group may contain an ether bond);
r and s satisfy the relationships 1≦r≦4, 1≦s≦4, and 2≦r+s≦6;
R ¹¹ is an alkyl group having 1 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof) or an alkenyl group having 2 to 18 carbon atoms (linear, branched, cyclic, or a combination thereof), preferably an alkyl group having 10 to 18 carbon atoms or an alkenyl group having 10 to 18 carbon atoms;
^OA4 is an oxyethylene group or an oxypropylene group;
n4 is 1 to 100, 1 to 80, or 5 to 80;
A ⁵ O is an ethylene oxide group or a propylene oxide group;
n5 is 1 to 100, 1 to 80, or 5 to 80;
n4+n5 is 20 to 80.

Formula (5) R ¹² O-(C ₂ H ₄ O) _n -R ¹³

In formula (5), R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents an integer from 1 to 20, provided that when R ¹² and R ¹³ are both hydrogen atoms, n represents an integer from 2 to 20.

When R ¹² in formula (5) is an alkyl group having 1 to 4 carbon atoms, it is a methyl group, an ethyl group, a propyl group, or a butyl group, and when it is a propyl group or a butyl group, it may be linear, branched, or cyclic. R ¹² is preferably a hydrogen atom or a methyl group.

When R ¹³ in formula (5) is an alkyl group having 1 to 4 carbon atoms, it is a methyl group, an ethyl group, a propyl group, or a butyl group, and when it is a propyl group or a butyl group, it may be linear, branched, or cyclic. R ¹³ is preferably a hydrogen atom or a methyl group.

In formula (5), n is preferably an integer of 1 to 15, and more preferably an integer of 1 to 10. When R ¹² and R ¹³ are both hydrogen atoms, n is preferably an integer of 2 to 15, and more preferably an integer of 2 to 10.

Preferred examples of the chemical substance represented by formula (5) are given below.
R ¹² is a hydrogen atom or a methyl group;
R ¹³ is a hydrogen atom or a methyl group;
n is an integer from 2 to 15 or an integer from 2 to 10.

[Other materials]
The geopolymer composition of the present disclosure may contain other chemical admixtures other than the chemical admixture having an oxyalkylene group, including various chemical admixtures conventionally used in geopolymer mortar or concrete or cement mortar or concrete.

The geopolymer composition of the present disclosure may contain a reinforcing material. Examples of reinforcing materials include metal fibers, carbon fibers, glass fibers, and basalt fibers.

<Method of manufacturing geopolymer composition>
The geopolymer composition of the present disclosure can be obtained by mixing the above-mentioned materials. The mixing of the materials can be carried out, for example, by kneading using a mixer.

The order of mixing the materials when preparing the geopolymer composition is not limited. For example, first mix the active filler and aggregate, then add the alkaline solution and knead, and then add the chemical admixture and knead to obtain the geopolymer composition.

The mixing ratio of the active filler and the alkaline solution may be set appropriately depending on the type of active filler and the type and concentration of the alkaline solution. For example, 10 to 100 parts by mass of the alkaline solution is mixed with 100 parts by mass of the active filler.

In the geopolymer composition disclosed herein, it is presumed that the components contained in the blast furnace slag fine aggregate exhibit the same reactivity as the active filler, and the surface of the blast furnace slag fine aggregate becomes part of the geopolymer structure. Therefore, it is preferable to increase the amount of alkaline solution used as the mass ratio of the blast furnace slag fine aggregate to the entire fine aggregate increases.

<Hardened geopolymer>
The hardened geopolymer of the present disclosure can be obtained by hardening the geopolymer composition of the present disclosure. Specifically, the geopolymer composition is poured into a formwork and hardened to obtain a hardened geopolymer. The geopolymer composition poured into the formwork may be subjected to a treatment such as degassing according to a conventional method. The geopolymer composition poured into the formwork generally hardens by a condensation polymerization reaction accompanied by dehydration to form a hardened body.

The curing temperature and curing time of the hardened geopolymer body of the present disclosure are not limited. Depending on the target mechanical strength of the hardened geopolymer body, for example, heat curing, steam curing, autoclave curing, underwater curing, air curing, room temperature curing, sealed curing, or a combination of these may be performed.

The geopolymer composition and hardened geopolymer body of the present disclosure will be specifically described below with reference to examples. The geopolymer composition and hardened geopolymer body of the present disclosure are not limited to the following examples.

[material]
The following materials were prepared for the geopolymer composition:
(1) Activated filler: ground granulated blast furnace slag (BFS): density 2.91 g/cm ³ , fineness 4220 cm ² /g
Fly ash (FA): density 2.28 g/cm ³ , fineness 3670 cm ² /g
(2) Alkaline solution/sodium silicate solution (WG): sodium silicate No. 2, density 1.50 g/ ^cm3
Sodium hydroxide solution (NH): molar concentration 10 mol/l, density 1.33 g/cm ³
Water (W): Tap water (3) Fine aggregate Blast furnace slag fine aggregate (BFSS): Bone dry density 2.76 g/cm ³ , water absorption rate 0.58%
・Standard sand (SS): absolute dry density 2.64 g/cm ³ , water absorption rate 0.42%
(4) Chemical admixture having an oxyalkylene group (CA): polyether compound, main compound is HO-(CH ₂ CH ₂ O) ₉ -H, weight average molecular weight 400, density 0.93 g/cm ³ , Toho Chemical Industry Co., Ltd.

[Preparation of Geopolymer Composition]
Geopolymer mortar was prepared as the geopolymer composition.
The materials were mixed as shown in Table 1, and CA was added at the addition rate (mass%) shown in Table 2, and mixed for 3 minutes with a mortar mixer to prepare a geopolymer composition. CA was added in mass% relative to the amount of active filler (total amount of BFS and FA).

[Evaluation of hardened geopolymer]
(1) Carbonation depth A 40mm x 40mm x 160mm test specimen was sealed and cured at a temperature of 20±2°C until it reached 4 weeks of age, and after demolding, it was stored for 4 weeks in an environment with a temperature of 20±2°C and a humidity of 60±5%. It was then stored in an environment with a temperature of 20±2°C, a humidity of 60±5%, and a carbon dioxide concentration of 5±0.2%. The carbonation depth (mm) was measured with reference to JIS A1152:2018. Due to the dimensions of the test specimen, the maximum value of the carbonation depth is 20mm. The measurement results are shown in Table 2.

(2) Compressive strength Test specimens were prepared using a formwork with a diameter of 50 mm and a length of 100 mm, and were sealed and cured at a temperature of 20±2° C. until the specified material age. The compression test was performed in accordance with JIS A1108:2018 at material ages of 1 week and 4 weeks. The test results are shown in Table 2.

Examples in which the fine aggregate is blast furnace slag fine aggregate and contains a chemical admixture having an oxyalkylene group show a slow carbonation rate and high compressive strength.

Comparing Examples 1 to 3 and Comparative Examples 3 to 5, it can be seen that the higher the content of the chemical admixture having an oxyalkylene group, the slower the neutralization rate, and the lower the content of the chemical admixture having an oxyalkylene group, the higher the compressive strength.

Claims (4)

An active filler, an alkaline activator , and water,
Blast furnace slag fine aggregate;
and at least one selected from the group consisting of an ester compound having an oxyalkylene group, an ether compound having an oxyalkylene group, and a glycol compound having an oxyalkylene group ,
The mass ratio of the blast furnace slag fine aggregate to the entire fine aggregate is 30 mass% to 100 mass%,
the total content of the ester-based compound having an oxyalkylene group, the ether-based compound having an oxyalkylene group, and the glycol-based compound having an oxyalkylene group is 0.5% by mass to 5% by mass based on the total amount of the active filler;
Geopolymer composition. The geopolymer composition according to claim 1 , comprising an ether-based compound having an oxyalkylene group, wherein the total content of the ether-based compound having an oxyalkylene group is 0.5% by mass to 5% by mass based on the total amount of the active filler. The geopolymer composition according to claim 1 or 2, wherein the active filler comprises at least one of fly ash and ground granulated blast furnace slag. A geopolymer hardened body which is a hardened product of the geopolymer composition according to any one of claims 1 to 3.