Method for designing compounding proportion for geopolymer composition, method for producing geopolymer concrete, and method for producing secondary product made of geopolymer concrete

Abstract

Provided is a method for designing a compounding proportion for a geopolymer composition, the method being for producing a geopolymer composition that has desired compressive strength levels at given concrete ages. The method comprises (1) using a given geopolymer material to obtain relationships between water / geopolymer material ratios and compressive strength levels of the cured geopolymer objects at given concrete ages, and determining, from the relationships, a water / geopolymer material ratio which brings about desired compressive strength levels at the given concrete ages.

Description

Method for designing mixes of geopolymer compositions, method for manufacturing geopolymer concrete, and method for manufacturing secondary products made of geopolymer concrete

[0001] The present invention relates to a method for determining the water to geopolymer material usage ratio (hereinafter also referred to as the water / geopolymer material ratio), fine aggregate rate, and unit water volume necessary for producing geopolymer concrete having performance that meets customer requirements, and a method for efficiently producing pre-hardened geopolymer concrete using the water / geopolymer material ratio, fine aggregate rate, and unit water volume determined by the method, and for producing secondary geopolymer concrete products.

[0002] In recent years, CO in the construction industry ２ To reduce CO emissions during manufacturing, ２ There is a demand for alternative materials to Portland cement, which produces waste products. Geopolymers have attracted attention as a solution. Non-Patent Document 1 describes geopolymers as hardened bodies produced by adding alkaline materials to industrial by-products such as coal ash, ground blast furnace slag, and sewage sludge, and then subjecting them to a condensation polymerization reaction.

[0003] Efforts to Promote the Practical Use of Geopolymer Technology in the Civil Engineering Field, Concrete Engineering, Vol. 61, No. 10, 2023.10

[0004] According to Non-Patent Document 1, geopolymers are made by combining three or more materials to form a hardened body. Therefore, the properties of the geopolymer, such as its fluidity and strength, are greatly influenced by the amounts and balance of these materials used. Therefore, the mix design required to obtain geopolymer concrete with the desired properties is complex. Furthermore, mix design methods for geopolymer concrete are not systematically organized, making it difficult to quickly determine the optimal geopolymer concrete mix during production. Deviation from this optimal geopolymer concrete mix can result in failure to produce geopolymer concrete that meets customer requirements, or the overall cost of the geopolymer concrete may increase, making it uneconomical.

[0005] Therefore, the present invention first aims to provide a method for easily designing mixes for geopolymer compositions such as geopolymer concrete having compressive strength in accordance with customer requirements. It also aims to provide a method for easily designing mixes for geopolymer concrete having compressive strength and slump or slump flow in accordance with customer requirements, and a method for producing the same at low cost.

[0006] The inventors of the present invention have conducted extensive research to solve the above problems. They have discovered that the compressive strength at each age of a geopolymer composition using geopolymer materials manufactured using the same geopolymer components in the same proportions is determined solely by the ratio of water to geopolymer material used, and that the slump and slump flow of geopolymer concrete are determined by both the fine aggregate ratio and the unit water content. As a result of further investigation, they have completed the present invention.

[0007] That is, the present invention is as follows: [1] A method for designing a geopolymer composition mix for producing a geopolymer composition having a desired compressive strength at a predetermined age using a predetermined geopolymer material, (1) determining the relationship between the water / geopolymer material ratio and the compressive strength at a predetermined age in a hardened geopolymer body, and determining the water / geopolymer material ratio that exhibits the desired compressive strength at the predetermined age from the relationship.

[0008] [2] The geopolymer composition is geopolymer concrete, and a mix design method for producing geopolymer concrete having a desired compressive strength and a desired slump or slump flow at a predetermined age, (2) determining the relationship between the fine aggregate rate and the slump or slump flow at the water / geopolymer material ratio determined in (1), and from the relationship, determining the maximum fine aggregate rate exhibiting the maximum slump or slump flow, and determining the fine aggregate rate within ±10% by mass of the maximum fine aggregate rate, (3) determining the relationship between the unit water content and the slump or slump flow at the water / geopolymer material ratio determined in (1) and the fine aggregate rate determined in (2), and from the relationship, determining the unit water content exhibiting the desired slump or slump flow, The mix design method for the geopolymer composition described in [1] above.

[0009] [3] In the above (1), the relationship between the water / geopolymer material ratio and the compressive strength of a plurality of ages including a predetermined age in the geopolymer hardened body for a predetermined geopolymer material is determined in advance, and in the above (2), the relationship between the fine aggregate ratio and the slump or slump flow at a plurality of water / geopolymer material ratios that may be determined in the above (1) is determined in advance. A method for designing a geopolymer composition according to the above [2].

[0010] [4] The geopolymer material contains at least one of blast furnace slag ground powder or fly ash, and contains at least an alkali metal silicate as an alkaline source. [5] The geopolymer composition composition design method according to any one of [1] to [3] above. [4] The alkali source contains an alkali metal silicate and an alkali metal carbonate. [6] The geopolymer composition composition design method according to [4] or [5] above, wherein the alkali metal silicate is sodium silicate powder. [7] The geopolymer composition composition design method according to [5] or [6] above, wherein the alkali metal carbonate is sodium carbonate powder.

[0011] [8] A method for producing unhardened geopolymer concrete, which comprises preparing unhardened geopolymer concrete with a water / geopolymer material ratio, fine aggregate ratio, and unit water content determined by the method described in any one of [2] to [7] above. [9] A method for producing unhardened geopolymer concrete with a water / geopolymer material ratio, fine aggregate ratio, and unit water content determined by the method described in any one of [2] to [7] above, and using the unhardened geopolymer concrete to produce a geopolymer concrete secondary product.

[0012] According to the present invention, it is possible to easily design a mix of geopolymer compositions having the desired compressive strength in accordance with customer requirements. Furthermore, it is possible to produce geopolymer concrete that satisfies the desired compressive strength, slump, or slump flow at a given age. Furthermore, it is possible to greatly simplify the mix adjustment of geopolymer concrete. Furthermore, it is possible to optimize the geopolymer concrete mix from an economical standpoint, thereby maximizing cost reduction.

[0013] This is a diagram showing the relationship between the water / geopolymer material ratio and compressive strength at each material age. This is a diagram showing the relationship between the fine aggregate ratio and slump when the water / geopolymer material ratio and unit water content are constant. This is a diagram showing the relationship between the fine aggregate ratio and compressive strength at each material age when the water / geopolymer material ratio and unit water content are constant. This is a diagram showing the relationship between the unit water content and slump when the water / geopolymer material ratio and fine aggregate ratio are constant. This is a diagram showing the relationship between the unit water content and slump flow when the water / geopolymer material ratio and fine aggregate ratio are constant. This is a diagram showing the relationship between the unit water content and compressive strength at each material age when the water / geopolymer material ratio and fine aggregate ratio are constant.

[0014] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. In this specification, "parts" and "%" are based on mass unless otherwise specified.

[0015] (Geopolymer material) The geopolymer material used in the present invention is not particularly limited, but preferably contains at least one of blast furnace slag powder or fly ash, and at least an alkali metal silicate as an alkali source. The alkali source is preferably a powder, as this makes it easier to design the composition.

[0016] (Fly ash) Fly ash is fine ash that is collected from the exhaust gas by a dust collector, among the ash by-products of combustion of coal and / or biomass fuel in a boiler of a thermal power plant or the like. ２ , Al ２ O ３ Fly ash for concrete, which is primarily composed of the above and is classified into types I to IV according to JIS A 6201 based on particle size and flow value, is preferred. Although the fly ash is not particularly limited, types I and II, which have a fine particle size and are highly reactive, are more preferred.

[0017] (Ground granulated blast furnace slag) Ground granulated blast furnace slag is produced when producing pig iron, and contains CaO, SiO ２ , Al ２ O ３ The blast furnace slag contains, as its main components, MgO. Examples of ground granulated blast furnace slag include those containing 20% ​​by mass or more and 60% by mass or less of calcium, calculated as calcium oxide (CaO). The type of blast furnace slag is not particularly limited, and either granulated blast furnace slag or slowly cooled blast furnace slag may be used, with granulated blast furnace slag being preferred from the standpoint of reactivity. In particular, the use of ground granulated blast furnace slag 4000 for concrete, as specified in JIS A 6206, is more preferred from the standpoint of the strength development and shrinkage at room temperature of the geopolymer concrete produced using the resulting geopolymer material. The ground granulated blast furnace slag used may also be treated by heating, carbonation, the addition of chemicals, or the like.

[0018] The fly ash content of the total mass of fly ash and ground granulated blast furnace slag can be 0 to 90% by mass, and is preferably 50 to 85% by mass from the viewpoint of the durability of geopolymer concrete. A content of 50% by mass or more is preferable from the viewpoint of maintaining good fluidity and achieving sufficient workability when the geopolymer material is mixed with water and aggregate to form geopolymer concrete, and also from the viewpoint of expanding the effective use of fly ash. Furthermore, a content of 90% by mass or less ensures good strength development of the geopolymer concrete at early ages.

[0019] (Alkaline Source) The alkali source contains alkali metal ions (Li ＋ , Na ＋ , K ＋ It is a salt containing alkali metals such as alkali metal silicates, alkali metal carbonates, and alkali metal hydroxides. The combined use of alkali metal silicates and alkali metal carbonates is preferred because they have a relatively low heat of solution, do not adversely affect the mixing process, and can produce geopolymer concrete with excellent compressive strength when cured at room temperature. The alkali metal salt may be in either a liquid or powder form, or in the form of an anhydrous salt, hydrate, or aqueous solution. Powder form is preferred because of its ease of transport and application.

[0020] As described above, the alkali metal silicate is preferably in the form of a powder because of its high transportability and workability. As the alkali metal silicate powder, sodium silicate powder (SiO ２ / NaO ２ Examples of suitable powders include sodium silicate powder (SiO 2 ), potassium silicate powder, potassium metasilicate powder, and lithium silicate powder (molar ratio: about 1.95 to 3.4), and sodium metasilicate powder (type 1, type 2), potassium silicate powder, potassium metasilicate powder, and lithium silicate powder. Sodium silicate powder (SiO 2 ) is preferred because it has excellent strength and durability and is a relatively inexpensive powder material. ２ / NaO ２ Molar ratio: about 1.950 to 2.2, H ２ O=about 20% by mass is preferred.

[0021] As described above, the alkali metal carbonate is preferably in powder form because of its high transportability and workability. ２ CO ３ ), potassium carbonate (K ２ CO ３ ), lithium carbonate (Li ２ CO ３ Sodium carbonate powder is preferred because it is relatively inexpensive and highly reactive with ground slag.

[0022] The molar ratio AL / W of the alkali metal element (AL) to water (W) constituting the alkali source is preferably 0.05 to 0.3. By setting the AL / W ratio to 0.05 or more, the compressive strength of the hardened geopolymer can be ensured even at room temperature, and by setting the AL / W ratio to 0.3 or less, the fluidity of the geopolymer composition can be ensured, making it easy to use in field work. From the above perspective, the AL / W ratio is more preferably 0.05 to 0.18, and even more preferably 0.08 to 0.12.

[0023] The molar ratio Si / W of silicon ions (Si) to water (W) constituting the alkalinity source is preferably 0.035 to 0.085. A Si / W ratio of 0.035 or more ensures the compressive strength of the hardened geopolymer, while a Si / W ratio of 0.085 or less ensures low viscosity and fluidity for on-site use. From the above perspective, a Si / W ratio of 0.050 to 0.070 is even more preferable.

[0024] (Geopolymer composition) In the present invention, the geopolymer composition is a concept including geopolymer paste (geopolymer cement) that does not contain aggregate, geopolymer mortar that contains fine aggregate, and geopolymer concrete that contains fine aggregate and coarse aggregate, and refers to a mixture of raw materials and a hardened product.

[0025] (Compressive Strength) In the present invention, it is preferable to use values ​​measured in accordance with JIS A 1108 (Testing Method for Compressive Strength of Concrete) as the compressive strength at each age. However, the present invention is not limited to this, and it is sufficient to determine and agree on the measurement method and conditions with the customer as necessary.

[0026] (Slump and Slump Flow) In the present invention, the slump and slump flow may be values ​​measured according to, for example, JIS A 1101 (Concrete Slump Test Method) and JIS A 1150 (Concrete Slump Flow Test Method).

[0027] In the present invention, the water / geopolymer material ratio is considered in order to produce a geopolymer composition that satisfies the desired compressive strength at a predetermined age using a predetermined geopolymer material. Here, the water / geopolymer material ratio is the ratio of the water / geopolymer material to the water content of 1 m of the geopolymer composition. ３ The ratio of water to geopolymer material used is included within.

[0028] Unlike ordinary cement, geopolymer materials are hardened by combining an active filler such as ground blast furnace slag with an alkali source. Therefore, it is common knowledge that the properties of geopolymer compositions manufactured using geopolymer materials are significantly influenced by the type and amount (balance) of these active fillers and / or alkali sources. Conventionally, the properties of geopolymer compositions have been adjusted by adjusting the type and amount of these materials. In particular, the type and amount of alkali source are considered important for adjusting compressive strength, and this adjustment has been primarily achieved by adjusting the alkali source.

[0029] However, after further intensive research into methods for adjusting compressive strength, the inventors discovered that the relationship between the water / geopolymer material ratio and compressive strength is a simple linear function (proportional relationship). They found that a geopolymer composition with the desired compressive strength can be easily obtained by simply adjusting the water / geopolymer material ratio, without using the complex and experience-requiring method of adjusting the alkali source.

[0030] Furthermore, in the present invention, by adjusting the water / geopolymer material ratio, fine aggregate percentage, and unit water content, an appropriate mix can be obtained to produce geopolymer concrete that satisfies the desired compressive strength at a specified age and the desired slump or slump flow.The following relationships are used to quickly determine the appropriate water / geopolymer material ratio, fine aggregate percentage, and unit water content.

[0031] Here, the fine aggregate ratio is the ratio of the absolute volume of fine aggregate to the absolute volume of all aggregate in concrete, and is an index generally used in the mix design of cement concrete. The fine aggregate ratio is calculated using the following formula. The unit water content is the amount of water per 1 m of concrete. ３ is the mass of water contained within.

[0032]

[0033] That is, the first relationship is the relationship between the water / geopolymer material ratio and the compressive strength at a specified age in hardened geopolymer concrete prepared using geopolymer material of a certain composition; the second is the relationship between the fine aggregate ratio of the geopolymer before hardening and the slump or slump flow when the water / geopolymer material ratio is kept constant; and the third is the relationship between the unit water content of the geopolymer before hardening and the slump or slump flow when the water / geopolymer material ratio and the fine aggregate ratio are kept constant.

[0034] By using the mixing method of the present invention, it is possible to produce geopolymer concrete that satisfies the desired compressive strength and desired slump or slump flow at a specified age while minimizing the use of expensive geopolymer materials.

[0035] That is, the first relationship (see Figure 1) shows that the relationship between the water / geopolymer material ratio and compressive strength is a simple linear function, and this allows us to determine the minimum amount of geopolymer material required to obtain geopolymer concrete with the desired compressive strength at a given age. Furthermore, the third relationship (see Figures 4 and 5) shows that increasing the water content increases the slump or slump flow, and decreasing it decreases the slump or slump flow. Therefore, the second relationship (see Figure 2) determines the fine aggregate percentage that will achieve the highest possible slump or slump flow, even with a low water content. By using this fine aggregate percentage to determine the minimum water content per unit of water required to achieve the desired slump or slump flow, the water / geopolymer material ratio is fixed, as shown in the first relationship, and therefore the amount of geopolymer material required is minimized. As a result, the amount of expensive geopolymer material used can be reduced.

[0036] In addition, in order to efficiently respond to various customer requests regarding compressive strength and slump or slump flow using a geopolymer material of a certain specified composition, it is preferable to determine in advance the relationship between the water / geopolymer material ratio and the compressive strength of the hardened geopolymer body at multiple ages, including a specified age, as the first relationship, and then determine in advance the relationship between the fine aggregate ratio and slump or slump flow at multiple water / geopolymer material ratios that may be determined by the first relationship.

[0037] The mixing method of the present invention is described in detail below. Figure 1 shows the relationship between the compressive strength and water / geopolymer ratio of hardened geopolymer concrete prepared with a fixed geopolymer material composition at ages of 1 day, 3 days, 7 days, and 28 days. As shown in this figure, compressive strength increases as the water / geopolymer ratio decreases, and decreases as the water / geopolymer ratio increases. Furthermore, the relationship between the water / geopolymer ratio and compressive strength can be expressed as a simple linear function. From these results, the water / geopolymer ratio of geopolymer concrete that satisfies the desired compressive strength at a given age can be easily obtained by determining the relationship between the water / geopolymer ratio and compressive strength.

[0038] The data shown in FIG. 1 are values ​​for the compositions listed in Table 1 below.

[0039]

[0040] (Materials used) Fly ash: Type II fly ash (compliant with JIS A 6201, Kyushu Electric Power Co., Inc.'s Kyuden Fly Ash) Ground granulated blast furnace slag: Ground granulated blast furnace slag 4000 (compliant with JIS A 6206, Nippon Steel Blast Furnace Cement Co., Ltd.'s Esment 40P) Sodium carbonate powder: (Tokuyama Corporation's Na ２ CO ３ Sodium silicate powder: sodium silicate powder (manufactured by Tokuyama Corporation, bulk density: 320 g / L, SiO ２ Min: 53.6%, Na ２ O content: 28.0%, H ２ O = 18.4%) Coarse aggregate: Hard crushed sandstone 2010 (surface dry density 2.70 g / cm3) and 1505 (surface dry density 2.70 g / cm3) from Miyano, Yamaguchi City, Yamaguchi Prefecture ３ ), Fine aggregate: crushed sand produced in Kumehijiri, Shunan City, Yamaguchi Prefecture (surface dry density 2.64 g / cm ３ , coarse grain ratio 2.80) and dune sand from Onga, Fukuoka Prefecture (surface dry density 2.58 g / cm ３ , coarse grain ratio 1.21) was used.

[0041] Figure 2 shows the relationship between fine aggregate percentage and slump when the water / geopolymer material ratio is constant (the amount of water is also constant to achieve an appropriate slump). As shown in this figure, increasing or decreasing the fine aggregate percentage maximizes slump around a certain value. The fine aggregate percentage at which this slump is maximized is determined in advance. Even if the unit water content changes, the fine aggregate percentage at which the slump is maximized remains unchanged. By determining the fine aggregate percentage (preferable fine aggregate percentage) within a range of ±10% by mass of the fine aggregate percentage at which the slump is maximized (maximum fine aggregate percentage), the amount of geopolymer material required to produce geopolymer concrete with the specified performance can be minimized, resulting in improved durability and reduced production costs. Furthermore, as shown in Figure 3, the compressive strength remains constant when the fine aggregate percentage is increased or decreased, without affecting the water / geopolymer material ratio determined in the previous section. The preferable fine aggregate percentage is preferably within ±8% by mass of the maximum fine aggregate percentage, more preferably within ±5% by mass, and even more preferably within ±3% by mass.

[0042] The data shown in Figures 2 and 3 are values ​​for the compositions listed in Table 2 below.

[0043]

[0044] S / A refers to the fine aggregate ratio.

[0045] Figure 4 shows the relationship between unit water content and slump when the water / geopolymer material ratio and fine aggregate ratio are constant, and Figure 5 shows the relationship between unit water content and slump flow when the water / geopolymer material ratio and fine aggregate ratio are constant. As shown in Figure 4, increasing the unit water content increases the slump, while decreasing it decreases it. Similarly, the slump flow shown in Figure 5 increases when the unit water content increases and decreases when it decreases. In other words, a wide range of fluidity can be achieved by adjusting the unit water content. Therefore, geopolymer concrete that meets the customer's fluidity requirements can be easily obtained by determining the relationship between unit water content and slump or slump flow at the water / geopolymer material ratio and fine aggregate ratio obtained from the first and second relationships above. Furthermore, as shown in Figure 6, compressive strength remains constant when the unit water content is increased or decreased, without affecting the water / geopolymer material ratio determined from the first relationship.

[0046] The data shown in Figures 4 to 6 are for the compositions listed in Table 3 below.

[0047]

[0048] The strength and fluidity of the geopolymer concrete vary depending on the composition of the geopolymer material. Furthermore, the strength and fluidity of each material that makes up the geopolymer concrete often vary depending on the manufacturing date, manufacturer, and place of origin. Therefore, it is preferable to determine the above relationship each time the composition of the geopolymer material and the combination of the constituent materials of the geopolymer concrete change.

[0049] In the present invention, from the above relationship, the water to geopolymer material ratio, fine aggregate ratio and unit water content can be determined to produce geopolymer concrete having the desired compressive strength and desired slump or slump flow at a predetermined age as follows.

[0050] That is, the water / geopolymer material ratio that will produce the desired compressive strength at a given age is determined using the relationship shown in Figure 1. Next, the fine aggregate percentage that will produce the maximum slump or slump flow is determined using the relationship shown in Figure 2, and the preferred fine aggregate percentage is determined. Furthermore, the unit water content that will produce the desired slump or slump flow at the water / geopolymer material ratio and the preferred fine aggregate percentage can be determined using the relationship shown in Figure 4 or Figure 5.

[0051] The specific mix design method is as follows: In this example, the compressive strength at 28 days is 45 N / mm ２ Assume that a geopolymer concrete with a slump of 18 cm is required by the customer.

[0052] (1) Mix several concrete samples with different water / geopolymer ratios in advance and conduct strength tests at several ages to determine the relationship between the water / geopolymer ratio and strength. Since concrete strength control is often performed between 1 and 28 days, it is best to keep the age within this range.

[0053] If the relationship between the water / geopolymer material ratio and strength is as shown in Figure 1, the customer's requirement for a compressive strength of 45 N / mm2 at 28 days old will be met. ２ Since the water / geopolymer material ratio that satisfies the above and is an economical blend that uses a small amount of geopolymer material is 36%, the water / geopolymer material ratio is determined to be 36%.

[0054] (2) Mix concrete with multiple water / geopolymer ratios that can be determined in (1) in advance, and conduct slump tests for three to five mixes with different fine aggregate percentages to determine the relationship between the fine aggregate percentage and slump or slump flow for each water / geopolymer ratio. The unit water volume used is the unit water volume that results in a slump of 8 to 18 cm. Slumps are compared at the same water / geopolymer ratio, and the fine aggregate percentage that results in the largest slump is optimal. Instead of determining the relationship in advance, slump tests can be conducted at the water / geopolymer ratios determined in (1) and the relationship for the water / geopolymer ratio determined in (1) can be determined each time. This minimizes the unit water volume required to achieve the same slump, resulting in a more economical mix using less geopolymer material.

[0055] If the relationship between fine aggregate percentage and slump is as shown in Figure 2, the optimum fine aggregate percentage is 43%. In this case, the compressive strength is not affected by the fine aggregate percentage, as shown in Figure 3.

[0056] (3) The unit water volume required to obtain the desired slump or slump flow is calculated using the water / geopolymer material ratio and fine aggregate percentage calculated in (1) and (2). Since the relationship between the unit water volume and the slump or slump flow is simply proportional, as shown in Figure 4 or Figure 5, the required unit water volume can be easily obtained. If the relationship between the slump and unit water volume for the water / geopolymer material ratio (36%) and fine aggregate percentage (43%) calculated in (1) and (2) is as shown in Figure 4, a unit water volume of 132 kg / m3 is required to obtain the desired slump of 18 cm. ３ In this case, as shown in Figure 6, the compressive strength is not affected by the unit water content.

[0057] Therefore, the compressive strength at 28 days is 45 N / mm ２ To produce geopolymer concrete with a slump of 18 cm, the water / geopolymer material ratio is 36%, the fine aggregate ratio is 43%, and the unit water content is 132 kg / m ３ This can be done as follows.

[0058] When producing geopolymer concrete, the above-mentioned materials may be mixed in the same manner as in the case of general cement concrete, and the mixing method may be any method carried out in ready-mix concrete factories without any particular restrictions.

[0059] When producing geopolymer concrete, any water commonly used in general concrete production can be used without any particular restrictions. Specifically, tap water, groundwater, etc. can be used as long as it conforms to JIS A 5308 "Ready-Mixed Concrete." Furthermore, any known coarse aggregate and fine aggregate commonly used in general concrete production can be used without any particular restrictions. Specifically, crushed stone, crushed sand, river gravel, dune sand, sea sand, limestone aggregate, etc.

[0060] In addition, in the present invention, geopolymer concrete can be mixed with the mix determined by the method of the present invention and a secondary concrete product can be produced from the mixed geopolymer concrete. Secondary concrete products made from geopolymer concrete using the present invention can be produced according to the same standard method as for general secondary concrete products, and the production method can be any method carried out in a secondary concrete product factory without any particular restrictions.

Claims

1. A method for designing a geopolymer composition mix to produce a geopolymer composition having a desired compressive strength at a predetermined age using a predetermined geopolymer material, comprising: (1) determining the relationship between the water / geopolymer material ratio and the compressive strength of the hardened geopolymer at a predetermined age, and from said relationship, determining the water / geopolymer material ratio that provides the desired compressive strength at the predetermined age.

2. The geopolymer composition is geopolymer concrete, and a mix design method for producing geopolymer concrete having a desired compressive strength at a specified age and a desired slump or slump flow comprises: (2) determining the relationship between the fine aggregate ratio and the slump or slump flow at the water / geopolymer material ratio determined in (1), determining the maximum fine aggregate ratio that exhibits the maximum slump or slump flow from the relationship, and determining the fine aggregate ratio within a range of ±10% by mass of the maximum fine aggregate ratio; (3) determining the relationship between the unit water content and the slump or slump flow at the water / geopolymer material ratio determined in (1) and the fine aggregate ratio determined in (2), and determining the unit water content that exhibits the desired slump or slump flow from the relationship. The mix design method for a geopolymer composition according to claim 1.

3. In (1), the relationship between the water / geopolymer material ratio and the compressive strength of the hardened geopolymer body at multiple ages, including the specified age, for a specified geopolymer material is determined in advance, and in (2), the relationship between the fine aggregate ratio and the slump or slump flow for multiple water / geopolymer material ratios that may be determined in (1) is determined in advance. A method for mix design of a geopolymer composition as described in claim 2.

4. A method for designing a geopolymer composition according to claim 1 or 2, wherein the geopolymer material contains at least one of ground granulated blast furnace slag or fly ash, and contains at least an alkali metal silicate as an alkali source.

5. The method for formulating a geopolymer composition according to claim 4, wherein the alkali source comprises an alkali metal silicate and an alkali metal carbonate.

6. The method for designing a geopolymer composition according to claim 5, wherein the alkali metal silicate is sodium silicate powder.

7. The method for designing a geopolymer composition according to claim 5, wherein the alkali metal carbonate is sodium carbonate powder.

8. A method for producing unhardened geopolymer concrete, comprising preparing unhardened geopolymer concrete with a water / geopolymer material ratio, fine aggregate rate, and unit water content determined by the method of claim 2.

9. A method for producing a secondary geopolymer concrete product, comprising preparing pre-hardened geopolymer concrete with the water / geopolymer material ratio, fine aggregate rate, and unit water content determined by the method of claim 2, and using the pre-hardened geopolymer concrete to produce a secondary geopolymer concrete product.

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