JP2016079046A - Additive for geopolymer and geopolymer hardening body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for geopolymer capable of improving workability (adjustment of setting time) of a geopolymer containing an active filler with CaO high content such as a blast furnace slag fine particles for example as an aluminosilicate source and providing a cured body excellent in further appearance without damaging flowability and strength development.SOLUTION: There is provided an additive for geopolymer consisting of a composition containing one or more kind of salt of aliphatic oxycarboxylic acid having hydroxyl value of 250 to 1500 mgKOH/g and acid value of 250 to 950 mgKOH/g with mass weighted average value of hydroxyl value/acid value of the aliphatic oxycarboxylic acid of 0.40 or more and less than 5.00.SELECTED DRAWING: None

Description

  The present invention relates to an additive for geopolymer and a cured geopolymer. More specifically, it relates to an additive for geopolymer that can adjust the setting time of the blended geopolymer appropriately, has excellent strength development in the cured product, and is also excellent in improving the surface appearance of the cured geopolymer. is there.

Concrete is used as a construction material, and its production volume is enormous. The total global production of cement, the main raw material for concrete, is 2.84 billion tons (2008). In cement production, large amounts of carbon dioxide are emitted by chemical decomposition of limestone and the use of thermal energy. If 1 ton of cement is produced in Japan, 0.725 ton of carbon dioxide is generated, and the carbon dioxide emissions of the cement industry account for 4% of the total nationwide emissions (2008). Therefore, it can be said that reducing the amount of cement used in the production of concrete is an extremely important approach to solving the global warming problem and building a sustainable society.
In Japanese industry, a large amount of waste is discharged daily from steel mills, coal-fired power plants and municipal waste incineration sites. These are called blast furnace slag, fly ash (hereinafter also referred to as FA), and municipal waste incineration ash, and some of these wastes are recycled, but they are overwhelmingly used as raw materials for cement. Mass effective utilization outside the cement field is an urgent issue. Looking over Japan, it is extremely difficult to secure a final disposal site for these wastes.

By the way, the geopolymer (hereinafter also referred to as GP) proposed in 1978 by Davidovites of France hardens when an active filler (aluminosilicate source) such as metakaolin is stimulated with an alkali silica solution (alkaline source), and cement. It is an inorganic material that can produce a cured body without using the. Cement accounts for about 60% of the total amount of CO ₂ emitted during the production of materials used in the construction field. Therefore, GP that does not need to use this has a CO ₂ emission of 80 to 90 compared to ordinary concrete. % (Non-Patent Document 1), and is attracting attention as a material that leads to reduction of environmental burden.
Since the active filler constituting the GP serves as a supply source of a cation necessary for curing the GP, it is desirable that the active filler contains a large amount of Si and Al as constituent elements. For natural products, metakaolin or the like is used. In addition, industrial by-products such as fly ash (hereinafter also referred to as FA), blast furnace slag fine powder (hereinafter also referred to as BFS), municipal waste incineration ash molten slag fine powder, and sewage sludge molten slag fine powder may be used as active fillers. it can. For this reason, GP is positioned as an important technology from the viewpoint of effective utilization of waste.

  Compared with general cement concrete, GP is very fast in compressive strength, and also has fire resistance, alkali-aggregate reaction resistance, and sulfate resistance resistance. Have. The GP curing reaction is said to proceed by polycondensation with the above-mentioned cation derived from the active filler and a silicic acid compound derived from an alkali silica solution (Patent Document 1), but details of the mechanism and the like are still clear. It is not.

Many examples of employing FA and BFS as active fillers in geopolymers have been studied so far. Among active fillers, GP that uses FA with a relatively low content of calcium oxide (CaO) alone has a long setting / setting time (for example, 1 day or more in normal temperature curing), and has good workability. Poor strength development. For example, the compressive strength of GP concrete cured at room temperature below 30 ° C. is 45 MPa or less (Non-patent Document 2), and the compressive strength of GP mortar cured at 25 ° C. in 3 months is only 15 MPa (Non-patent Document 3). It has been reported. On the other hand, GP using BFS as an active filler is very excellent in strength development, and the compressive strength in 28 days even at room temperature curing at 20 ° C. is 100 MPa or more, but the setting time at room temperature is about 10 to 40 minutes. It is very short and its workability is bad. For this reason, some examination examples using BFS and FA mixedly are reported for the purpose of improving the strength development property and denseness of GP (for example, Non-Patent Document 3 and Non-Patent Document 4).

In addition, with the aim of developing a technique for appropriately and simultaneously controlling the compressive strength and setting time of GP, a method for adjusting the setting time of a GP composition by using an admixture has been studied (Patent Document 2). For example, a method for adjusting the setting time of GP using sugars, acids, and chelating agents has been proposed.
In addition, in the use of a fluidizing agent in a geopolymer composite ultra-high performance concrete compound (Patent Document 3) and a curable refractory putty composition utilizing a geopolymer reaction, the average particle size is 10 to 300 nm. An example of blending synthetic rubber latex (Patent Document 4) has also been proposed.
Furthermore, an experimental study on changes in setting time and compressive strength of fly ash-based geopolymer mortar added with sucrose or citric acid has been reported (Non-Patent Document 5). In addition, by using potassium hydroxide as the metal hydroxide used for the alkali silica solution, and adjusting the concentration of potassium hydroxide and the molar ratio of SiO ₂ / K ₂ O of the alkali silica solution, GP using BFS is used. It has been pointed out that the setting time can be extended (Non-patent Document 6).

JP 2012-240852 A JP 2014-28726 A Special table 2013-545714 gazette JP 2013-60543 A

J. et al. Davidovits, Properties of geopolymer cements, Proceedings of 1st International Conference on Alaline Cements and Concrete, KIEV, Ukraine, pp. 131-149, 1994 D. Hardjitoand B.V.Ranga, Development and properties of low-calcium fly ash-based geopolymer concrete, Research Report, Curtin University of Technology, pp 48-49, 2005 F. Puetras et al., Alkali-activated fly ash / slag cement strength behavior and hydration products, Cement and Concrete Research, Vol. 30, 1625-1632, 2000 Kazuo Ichinomiya et al., Fly ash-based geopolymer formulation and high temperature resistance, concrete engineering annual papers, Vol. 36, no. 1,2014 Andri Kusbiantoro, et al., Development of sucrose and citric acid as the natural based admixture for fly ash based geopolymer, Proceedings of 3rd International Conference on Sustainable Future for Human Security, 2012 T.W.Cheng, J.P. Chiu, Fire-resistant geopolymer produced by granulated blast furnace slag, Minerals Engineering, Vol. 16, pp.205-210, 2003

As described above, the geopolymer (GP) still has many unclear points in the details of the curing mechanism, and the setting time and strength vary depending on the active filler used.
For example, as shown in Non-Patent Document 3 and Non-Patent Document 4, when BFS and FA are mixed and used, the setting time of GP changes depending on the mixing ratio of BFS, and particularly when the ratio of BFS is increased, the setting time is short. It has been reported that This result suggests that the CaO content in the active filler has a great influence on both the setting time of the GP and the strength after curing, and is particularly workable for active fillers containing high CaO such as BFS. Although there is a high demand for technology that achieves both strength development and strength development, no effective proposal has been made.
As an example of a technique for adjusting the setting time (workability) and strength development at the same time, Patent Document 2 described above has proposed a method for adjusting the setting time by adding an admixture. There is no specific data on what kind of admixture is effective for delaying the setting time with respect to the active filler, and their relationship is not clear.
Further, in Non-Patent Document 5, although it has been reported that the initial setting time can be adjusted, the setting time is only slightly extended when sucrose is used for the geopolymer using FA alone. In Non-Patent Document 6, the composition of the alkaline solution used for GP is limited to 15 moles of potassium hydroxide, and the SiO ₂ / K ₂ O molar ratio must be adjusted to 0.9 or less. In addition to increasing the amount of potassium used, the material cost increases, the material design is complicated, and it is difficult to control performance other than the setting time.
Thus, in order to ensure practical workability in geopolymers as well as to have the strength required for actual use, it is strongly desired to develop a technology that can adjust both the setting time and strength at the same time. ing.

In addition, in the study by the present inventors, in a geopolymer using BFS as an active filler or a geopolymer using a mixture of BFS and another active filler, an organic additive that has been used in cement concrete has been added. In this case, it was confirmed that the action expression was significantly different from that of cement concrete. Specifically, when a conventionally known compound (additive) is applied, the strength developability is impaired, and in addition, some additives may damage the appearance of the cured product in addition to the strength manifestation damage. It was confirmed.
Based on these various problems, the present invention can adjust the setting time of a geopolymer containing an active filler having a high CaO content such as blast furnace slag fine powder, municipal waste incineration ash molten slag fine powder, fluidized bed coal ash, etc. It is an object of the present invention to provide an additive for a geopolymer that can obtain a cured product that is further excellent in appearance without significantly impairing the previous fluidity and strength development of the cured product.

  As a result of investigations by the present inventors, by using an additive comprising one or more aliphatic oxycarboxylic acid compounds for the geopolymer, workability is improved without impairing strength development, and at the same time, surface aesthetics. It was found that an effect can also be obtained.

That is, the present invention is a geopolymer additive comprising a composition containing a salt of one or more aliphatic oxycarboxylic acids having a hydroxyl value of 250 to 1500 mg KOH / g and an acid value of 250 to 950 mg KOH / g. In addition, the present invention relates to an additive for geopolymer, wherein the weight-weighted average value of hydroxyl value / acid value of the aliphatic oxycarboxylic acid is 0.40 or more and less than 5.00.
In the additive for geopolymer of the present invention, the composition containing the salt of the aliphatic oxycarboxylic acid preferably contains a tartrate salt.
Further, the additive for geopolymer of the present invention contains at least one aluminosilicate source (for example, blast furnace slag, municipal waste incineration ash slag, sewage sludge incineration ash slag, and fluidized bed coal ash having a CaO content of 10 to 60% by mass. And a geopolymer formed from a mixture comprising at least one alkali source selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal silicates. Is preferred.

  The present invention also includes the additive for geopolymer, at least one aluminosilicate source having a CaO content of 10 to 60% by mass, an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal silicate. Also contemplated are geopolymer compositions comprising at least one selected alkali source and aggregate.

  Furthermore, the present invention is also directed to a cured geopolymer obtained by applying the additive for geopolymer to a geopolymer formed from a mixture containing the aluminosilicate source and the alkali source.

  The geopolymer additive of the present invention can adjust the setting time of the geopolymer, improves the workability before curing without impairing the strength development of the cured body, and at the same time has an excellent aesthetics on the surface of the cured body. A polymer cured body can be obtained.

[Additives for geopolymers]
As described above, various problems remain in the technologies that have been proposed so far in order to achieve both adjustment of the setting time and strength development of the cured product in the geopolymer. For example, in the method for adjusting the setting time with the admixture shown in Patent Document 2, according to the schematic diagram showing the adjustment result, in the GP using a Na-based alkaline solution as the alkali activator, carbonic acid corresponding to the chelating agent and the inert filler With the increase in the mixing ratio of the admixture composed of calcium (CaCO ₃ ) (the ratio of replacing the active filler), the setting time of GP is rapidly shortened. In the case of 30% substitution, the setting time is shortened to 15 minutes, and it is difficult to say that there is a setting delay effect due to the addition of the admixture. In addition, the present inventor conducted an experiment using, among the third admixtures proposed in Patent Document 2, oxycarboxylates such as sodium gluconate for GP, and some admixtures have a delay effect. In spite of this, a problem has been found that even if there is a delay effect, the strength development or appearance of the cured product is impaired.
The present invention is a composition comprising a salt of one or more aliphatic oxycarboxylic acids having a specific hydroxyl value and an acid value, and the hydroxyl value / acid value of the aliphatic oxycarboxylic acid is in a specific numerical range. By adopting the configuration, it has been found that not only the setting of the setting time and the strength development of the cured product are compatible, but also the appearance of the cured product is improved.
Hereinafter, the present invention will be described in detail.

In the present invention, the aliphatic oxycarboxylic acid has a hydroxyl value of 250 to 1500 mg KOH / g, an acid value of 250 to 950 mg KOH / g, and a hydroxyl value / acid value which is a ratio of the hydroxyl value to the acid value. Is 0.44 or more and less than 5.00. The hydroxyl value / acid value is preferably 0.50 or more and 4.00 or less, and more preferably 1.00 or more and 4.00 or less.
In addition, when using 2 or more types of aliphatic oxycarboxylic acid, the ratio of the said hydroxyl value and an acid value is the hydroxyl value which carried out the mass load average of the several aliphatic oxycarboxylic acid to be used / the acid value which carried out the mass load average. Calculated. In addition, when a combination of a plurality of types is used and the weight value averaged hydroxyl value / acid value is within the above numerical range (0.40 or more and less than 5.00), the aliphatic oxycarboxylic acid 1 The seed alone can be used even if the ratio between the hydroxyl value and the acid value is out of the numerical range.

  Examples of the aliphatic oxycarboxylic acid include glycolic acid, lactic acid, tartronic acid, glyceric acid, 2-hydroxybutyric acid, γ-hydroxybutyric acid, 3-hydroxybutyric acid, tartaric acid, malic acid, citric acid, isocitric acid, mevalonic acid, pantoin Aliphatic or alicyclic oxycarboxylic acids such as acid, gluconic acid, quinic acid and shikimic acid can be mentioned. These aliphatic oxycarboxylic acids can be used singly or in combination of two or more.

Among these, preferable aliphatic oxycarboxylic acids include lactic acid, malic acid, tartaric acid, citric acid, and gluconic acid. Tartaric acid is more preferable, and L-tartaric acid, which is easily available, is most preferable.
Moreover, when using in combination of 2 or more types, by making at least one into tartaric acid or gluconic acid, generation | occurrence | production of the white flower in the external appearance of a hardening body can be suppressed and it is preferable since the preferable surface external appearance can be obtained. Among them, preferable combinations include tartaric acid and malic acid, tartaric acid and gluconic acid, citric acid and gluconic acid, and the like. Among these two or more combinations, it is most preferable that one is tartaric acid.

  Examples of the salts of these aliphatic oxycarboxylic acids include alkali metal salts such as lithium salts, sodium salts and potassium salts, with sodium salts being preferred.

[Geopolymer]
As described above, the geopolymer to which the additive of the present invention is applied is composed of a mixture containing an aluminosilicate source such as an active filler and an alkali source such as an alkali silica solution.

<Aluminosilicate source: active filler>
The aluminosilicate source refers to a component containing aluminosilicate (xM ₂ O.yAl ₂ O ₃ .zSiO ₂ .nH ₂ O, M is an alkali metal) as a component, and a highly alkaline solution (alkaline silica solution) By contact, cations such as aluminum and silicon are eluted and have a function as a supply source thereof.
As suitable examples of aluminosilicate sources, 1) fly ash, clinker ash, fluidized bed coal ash, blast furnace slag fine powder, municipal waste incineration ash melt slag fine powder, red mud, silica fume, rice husk ash, and sewage sludge incineration ash melt Industrial waste such as slag fine powder, 2) natural aluminosilicate minerals such as metakaolin, and clay and its baked goods, and 3) volcanic ash.
Among these, the industrial waste of 1) is particularly suitable because there is no production area limitation and effective use of industrial waste resources as compared with other aluminosilicate sources.
In the present invention, as the aluminosilicate source, it is preferable to use at least one type having a CaO content of 10 to 60% by mass. As such an aluminosilicate source having a high CaO content, for example, blast furnace slag fine powder And municipal waste incineration ash slag fine powder, sewage sludge incineration ash slag fine powder, fluidized bed coal ash rich in CaO, and the like. In the present invention, it is particularly preferable to use fly ash in combination with at least one of the above-mentioned aluminosilicate sources having a high CaO content, and particularly to use blast furnace slag fine powder and fly ash in combination.

Blast furnace slag fine powder is a residue produced as a by-product when refining iron in the blast furnace, and is mainly composed of calcium oxide (CaO), silica (SiO ₂ ) and alumina (Al ₂ O ₃ ), and is standardized in JIS A6206. Yes. In particular, the blast furnace slag fine powder to be used preferably has a CaO ratio in the range of 30 to 60% by mass.
Municipal waste incineration ash slag is obtained by melting and cooling ash generated during incineration of municipal waste at a high temperature. Like blast furnace slag, oxides such as silicon, aluminum and calcium are the main components. is there. What has the ratio of CaO in the range of 15-45 mass% is used preferably.
Fluidized bed coal ash is ash generated from a pressurized fluidized bed coal boiler. For the purpose of desulfurization in the furnace, coal is burned by mixing fine limestone powder, and therefore, it is characterized by containing a larger amount of CaO than fly ash and clinker ash described later. Although fluidized bed coal ash does not satisfy the present JIS standard (JIS A 6201) of fly ash for concrete admixtures, it can be used as an alkali silicate source. The CaO content is 20 to 55% by mass, although it varies depending on the location where ash is generated.
The sewage sludge incinerated ash melt slag is obtained by concentrating and dewatering sludge generated by sewage treatment, and then melting and cooling the ash incinerated at about 800 ° C. at a higher temperature. Sewage sludge incineration ash is classified according to the type of flocculant added at the time of dehydration, that is, it is classified into lime-based incineration ash to which slaked lime and ferric chloride are added and polymer incineration ash to which polymer flocculant is added. . Although the CaO content of lime-based incinerated ash varies depending on the addition rate of slaked lime during dehydration, it is generally about 30 to 50% by mass. On the other hand, the CaO content of the polymer incineration ash is about 10% by mass or less. Therefore, as the aluminosilicate source used in the present invention, it is preferable to use slag by lime-based incinerated ash.

Fly ash is mainly composed of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ), and is specified in JIS A 6201 as I to IV types (JIS A 6201-2008) based on particle size and flow value. JIS type I and type II, which are fine in particle size and rich in reactivity, are particularly suitable as raw materials for geopolymers.
Clinker ash is obtained by pulverizing welded coal ash collected at the bottom of a coal-fired boiler.
Both fly ash and clinker ash are useful as an alkali silicate source because silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) components account for 70 to 80% of the total mass.

As described above, the geopolymer to which the geopolymer additive of the present invention is applied is at least one aluminosilicate source having a CaO content of 10 to 60% by mass, specifically, blast furnace slag fine powder, urban At least one kind of waste incineration ash slag fine powder, sewage sludge incineration ash molten slag fine powder and fluidized bed coal ash (rich in CaO) is included as an aluminosilicate source (active filler).
The blending ratio of the aluminosilicate source having a high CaO content in the active filler is 10% by mass to 100% by mass, preferably 30% by mass or more, based on the total mass of the active filler.
When using 2 or more types of active fillers, the ratio for which CaO accounts among the whole active fillers becomes like this. Preferably they are 10 mass%-60 mass%. The content of CaO can be adjusted by changing the proportion of fine powder or ash having a high CaO content.

<Alkali source: alkali silica solution>
In the present invention, the alkali source refers to an aqueous solution of a compound exhibiting high alkalinity, and has an action of activating cations such as aluminum and silicon by contacting them with the aluminosilicate source.
The compounds used for the alkali source are 1) alkali hydroxides such as sodium hydroxide and potassium hydroxide, 2) alkali carbonates such as sodium carbonate and potassium carbonate, and 3) alkalis such as sodium silicate and potassium silicate. In addition to silicates, combinations of these 1) to 3) can be suitably used.

Of the above, sodium compounds are more suitable in terms of price.
Moreover, 3) When using an alkali silicate, since it becomes a supply source of the silicic acid monomer (Si (OH) ₄ ) itself entrusted to geopolymer formation, it is still more suitable.
From these viewpoints, preferable examples of the alkali source compound include sodium silicate, sodium hydroxide, and a combination of sodium silicate and sodium hydroxide. It is also possible to replace a part of the sodium compound with the corresponding potassium compound within a range not impairing the economic efficiency (cost) in industrial implementation.
Accordingly, as the alkali source, an aqueous solution of potassium hydroxide, sodium hydroxide, sodium silicate or potassium silicate is preferably used, and an aqueous sodium silicate solution is particularly preferably used.
The aqueous sodium silicate solution is commonly called “water glass”, and a commercially available product can be used. The chemical composition preferably contains SiO ₂ = 20 to 40% and Na ₂ O = 5 to 20%.

The alkali ratio / water quantity molar ratio (hereinafter, molar ratio) constituting the alkali source is preferably 0.1 or more. The higher the molar ratio, the better the strength development of the resulting geopolymer cured body, so it is necessary to increase the amount of alkali added at the time of kneading and reduce the water, but on the other hand, the fluidity decreases as water is reduced, Filling the formwork becomes difficult. Therefore, the molar ratio is more preferably 0.15 or more.
The concentration of the alkaline aqueous solution used is preferably in the range of 20 to 50% by mass.

[Geopolymer composition]
The geopolymer composition of the present invention includes the geopolymer additive, an aluminosilicate source such as the active filler constituting the geopolymer, an alkali source such as an alkali silica solution, and an aggregate.

  In the production of the geopolymer composition, when a plurality of the active fillers are used, they are mixed to prepare an aluminosilicate source. A separately prepared alkali source is added to and mixed with the aluminosilicate source, and aggregate is further added and mixed to produce a geopolymer composition.

  As said aggregate, what is used for general concrete and mortar can be used suitably.

The geopolymer additive of the present invention may be added together when preparing the alkali source, or may be added after mixing the alkali source, the aluminosilicate source and the aggregate and kneaded uniformly. It is also possible to use the geopolymer additive as an aqueous solution or as a solid. It is also possible to produce a geopolymer using a premixed aluminosilicate source and a geopolymer additive and / or an aqueous solution of the additive.
The addition timing of the geopolymer additive can be mixed with either the aluminosilicate source or the alkali source, and further mixed with the rest of the geopolymer use material, but added to the premixed mixture of the aluminosilicate source and the alkali source. However, the latter (addition to the mixture) is preferred. Moreover, as an addition method, a required addition amount may be added all at once, and after adding a part of a required addition amount and kneading once, the remaining additive can also be added.
Regarding the blending design of the geopolymer, the ratio of the total mass of the alkali solution (alkali source: water glass + sodium hydroxide + water) to the total mass of the aluminosilicate source (active filler powder (B)) ([alkali solution / B ] × 100 (%)) can be appropriately set depending on the strength required for the structure or product, but is preferably 40 to 65% by mass in consideration of workability.
Further, the ratio of the constituent components of the alkaline solution, for example, the mass ratio represented by [total mass of water glass (WG)] / [total mass of sodium hydroxide (NaOH) or sodium hydroxide aqueous solution (NaOHaq)] Although it can be set as appropriate depending on the target setting time and strength of the cured polymer, it is preferably in the range of 1.0 to 4.0. This ratio can also be set by the volume ratio of water glass and sodium hydroxide aqueous solution.

  The following examples illustrate the invention. However, the present invention is not limited to these examples and comparative examples.

[Preparation of additive for geopolymer]
An oxycarboxylic acid compound shown in Table 1 and a 48 mass% sodium hydroxide aqueous solution (manufactured by Kaneka Corporation, product name “caustic soda”, specific gravity at 35 ° C .: 1.504, pure content: 48%, molar concentration: 18.1 mol / L) and ion-exchanged water were used to prepare geopolymer additives (30% aqueous solution of sodium salt) shown in Table 2 by neutralization reaction. The molar ratio of oxycarboxylic acid (acid) to sodium hydroxide (alkali) was 1: 1. Subsequently, the geopolymer additive aqueous solution was heated, concentrated, recrystallized and fractionated to obtain a solid geopolymer additive (sodium salt). In the following geopolymer mortar examples, an aqueous solution form geopolymer additive and a solid form geopolymer additive were used in combination in order to have the amount of water necessary for mortar formulation.

[Geopolymer mortar test]
48 mass% sodium hydroxide aqueous solution (manufactured by Kaneka Corporation, product name “caustic soda”, specific gravity at 35 ° C .: 1.504, pure content: 48%, molar concentration: 18.1 mol / L) per 100 parts by mass Then, 20 parts by mass of ion-exchanged water was added and mixed to prepare a 40% by mass aqueous sodium hydroxide solution (specific gravity: 1.43, molar concentration: 14.3 mol / L). Similarly, 60 parts by mass of ion-exchanged water is added to and mixed with 100 parts by mass of the 48% by mass sodium hydroxide aqueous solution, and a 30% by mass sodium hydroxide aqueous solution (specific gravity: 1.33, molar concentration 10.0 mol / L) is added. Prepared.

40 mass% or 30 mass% sodium hydroxide aqueous solution (NaOHaq) prepared by the above procedure and sodium silicate (WG) (product name “Sodium silicate No. 1” manufactured by Fuji Chemical Co., Ltd.), density: 1.534 , SiO ₂ / Na ₂ O molar ratio = 2.1, SiO ₂ : 30%, Na ₂ O: 15%) and ion-exchanged water (W) were mixed according to the unit amounts (g) in Table 3 and Table 10. And mix. 1 to 6 alkaline solutions (GP solutions) were prepared.
The alkaline solution does not contain a geopolymer additive.

  The additive for geopolymer shown in Table 2 is 3% by mass, 5% by mass or 7% by mass (solid content of sodium oxycarboxylate) based on the mass B or WS (g) of the active filler shown in Table 3 and Table 10. ). In addition, alkali solution / B (fly ash + blast furnace slag fine powder) or alkali solution / WS (city waste incineration ash molten slag fine powder) (both mass ratio,%) shown in Tables 3 and 10 are used for each component. It is a value calculated from the quantity.

<Measurement of mortar flow (0 stroke) and flow time>
A high-power mixer (manufactured by Maruto Seisakusho: CB-34) was used for kneading the mortar. No. in Table 3 or Table 10 1-No. In the formulation shown in FIG. 6, the active filler used was JIS type II fly ash (FA) and blast furnace slag fine powder 4000 (BFS), or municipal waste incineration ash molten slag fine powder. The alkali solution and the geopolymer additive prepared by the above procedure were weighed and mixed in a ratio to a predetermined active filler, respectively, mixed, then added to the active filler, and stirred at low speed (revolution 62 rpm, rotation 141 rpm) for 120 seconds.
After completion of the low-speed stirring, the operation of the mixer was stopped, and within 30 seconds after the stop, the mixer was set as No. 1 in Table 3 as fine aggregate (S). 1-No. 5 or No. 5 in Table 10. The standard sand for cement strength test was added with the composition shown in 6 (unit amount (g)), stirred again at low speed for 30 seconds, and then rapidly stirred at high speed (revolution 125 rpm, rotation 284 rpm) for 60 seconds. After completion of the high-speed stirring, the produced geopolymer mortar was filled into a JIS flow cone, and mortar flow (0 stroke) was measured according to JIS A 1171. Further, the time from when the flow cone was pulled up until the mortar flow reached 200 mm was measured as the flow time.

<Measurement of setting time>
The setting time was measured based on the setting test of JIS R 5201 (physical test method for cement). The geopolymer mortar produced by the above procedure is a sample container (conical shape of a top end outer diameter φ90 mm, an upper end inner diameter φ75 ± 3 mm, a lower end outer diameter φ100 mm, a lower end inner diameter φ85 ± 3 mm, and a height 40.0 ± 0.5 mm. ) And used for measurement of the setting time. The starting time was when the starting standard needle installed in the bigger needle device stopped at about 1 mm from the upper surface of the bottom plate. On the other hand, the termination time was set when the standard needle for termination was installed in the bigger needle device, and the trace of the needle was stopped on the surface of the geopolymer mortar, but the back of the attached small piece ring was not left. The time required for the start and the end was determined from the time when the mixing of the active filler and the alkaline solution was started.

In this mortar test, the amount of air was measured by the total mass method. From the result of measurement using a graduated cylinder, the amount of air was calculated by the following formula. The air content of all the geopolymer mortars in the examples and comparative examples was in the range of 3.0 to 4.0% by mass.
Air amount (%) = [1- (Geopolymer mortar mass) / (Geopolymer mortar mass at 0% air amount calculated from formulation)] × 100

<Measurement of compressive strength and evaluation of surface appearance>
In the measurement of the compressive strength, the prepared geopolymer mortar was filled in a plastic mold having a diameter of 5 cm and a height of 10 cm, and the specimen was sealed with a wrap. Thereafter, curing was performed in two patterns: curing at 20 ° C. and curing via 80 ° C. in a program-controlled thermostatic chamber (PWL-3KP, manufactured by ESPEC Corporation).
1) Curing method via 80 ° C:
Specifically, the curing method via 80 ° C. is as follows. After sealing the specimen, first curing is performed at 20 ° C. for 2 hours, and then the temperature is raised to 80 ° C. over 3 hours, and after reaching 80 ° C., curing is performed at the same temperature for 24 hours. Went. After curing, the sample was cooled to 20 ° C. over 6 hours, and then the specimen was demolded.
The material age at the time of demolding was set to 1 day, and then air curing was performed at a temperature of 20 ° C. and a humidity of 60% until the material age was 28 days, and the compressive strength at the material age of 28 days was measured according to the procedure of JIS A 1108. . For each of the examples or comparative examples, five specimens were prepared and measured, and the compressive strength (N / mm ² ), standard deviation σ, and CV value (standard deviation / average value) as average values were measured. Calculated.
Moreover, at the time of demolding after curing at 80 ° C., the appearance of the specimen was visually observed and evaluated according to the following evaluation criteria. In addition, the external appearance after completion of the air curing (age 28 days) was not confirmed in any of the specimens compared with the age 1 day.
・ Appearance Evaluation Criteria ◎ No white flower is observed on the surface of the specimen.
○ Slight whiteness is observed on the surface of the specimen (approximately less than 2% surface area).
X White flower is conspicuously observed on the surface of the specimen (approximately surface area of 2% or more).
2) Curing method only at 20 ° C:
Specifically, the curing method only at 20 ° C. was carried out at 20 ° C. for 1 day after sealing the specimen, and then the specimen was demolded. Thereafter, the specimen was subjected to air curing at 20 ° C. and a humidity of 60% for 28 days.
The compressive strength was measured according to the procedure of JIS A 1108 for each specimen at each age. For each example or comparative example, three specimens were prepared and measured at a material age of 7 and 28 days, and the compressive strength (N / mm ² ) as an average value thereof was calculated.

Tables 4 to 8 show the test results evaluated for the GP mortar fluidity (flow time, mortar flow), setting time, compressive strength after curing via high temperature, and appearance of the cured body in specimens subjected to high temperature curing. Shown in Table 11 shows the test results for evaluating the flowability, setting time, compressive strength after curing via high temperature, and appearance of the cured product, which were performed on the GP mortar prepared using municipal waste incineration ash molten slag fine powder as an active filler. Shown in
Table 9 shows the test results of evaluating the GP mortar fluidity, setting time, and compressive strength after curing in specimens subjected to curing at 20 ° C only.

  As shown in the above results, it is possible to adjust the setting time to an appropriate time (for example, around 40 to 60 minutes) by adding the geopolymer additive of the present invention to the geopolymer composition, that is, driving. It was confirmed that the geopolymer cured product having excellent aesthetics on the surface of the cured product can be obtained without impairing the workability of the cured product, and without impairing the strength development of the cured product. In addition, when the time for transportation and placement is long after the geopolymer is prepared, the decrease in fluidity due to water evaporation and curing reaction is large. In this case, adjustment of the curing reaction rate is important. From the test results of the setting time of the geopolymer shown in Table 11, it can be seen that long-time workability can be ensured and the working time can be adjusted by using the additive of the present invention. In addition, by using the additive for geopolymer of the present invention, the initial setting time of the geopolymer using a filler having a high CaO content can be extended by 1.4 to 2.1 times (when the additive is used and not used). The ratio of the initial time of condensation to 20 ° C. and normal temperature curing at 20 ° C. showed higher strength than the comparative example, and a high-strength geopolymer cured product of about 60 MPa or more could be produced.

Claims (5)

A geopolymer additive comprising a composition comprising a salt of one or more aliphatic oxycarboxylic acids having a hydroxyl value of 250 to 1500 mg KOH / g and an acid value of 250 to 950 mg KOH / g,
The additive for geopolymers wherein the weight-weighted average value of hydroxyl value / acid value of the aliphatic oxycarboxylic acid is 0.40 or more and less than 5.00. The additive for geopolymers of Claim 1 whose composition containing the salt of the said aliphatic oxycarboxylic acid contains tartrate. Including at least one aluminosilicate source having a CaO content of 10 to 60% by mass, and at least one alkali source selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal silicates The additive for geopolymers of Claim 1 or Claim 2 applied to the geopolymer formed from a mixture. The additive for geopolymer according to claim 1 or 2,
At least one aluminosilicate source having a CaO content of 10 to 60% by mass;
A geopolymer composition comprising at least one alkali source selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal silicates, and aggregates. A cured geopolymer obtained by applying the geopolymer additive according to claim 1 or 2 to the geopolymer according to claim 3.