Geopolymer concrete mix proportion design method

Abstract

The invention discloses a geopolymer concrete mix proportion design method, which is characterized in that an effective glue ratio and a linear relation between the effective glue ratio and geopolymer concrete compressive strength are provided, so that the pre-experimental quantity is remarkably reduced, efficient and accurate design of target working and mechanical properties is realized, the mix proportion can be flexibly adjusted according to requirements, and the working efficiency is improved. The method has good universality to different silicon-aluminum raw materials, is clear in overall idea, and is expected to be popularized as a standard design method. Comprising the following steps: 1) determining a relation parameter between slump and water consumption and a relation parameter between compressive strength and an effective glue ratio by a small amount of pre-experiments; the method comprises the steps of (1) determining a slump, (2) determining the water consumption according to the target slump, (3) determining the mass of an effective cementing material according to the target compressive strength, (4) determining the use amount of Na2O and SiO2 in an alkali activator and the use amount of a silicon-aluminum material, (5) calculating the use amount and mass fraction of a sodium silicate solution and a sodium hydroxide solution, (6) determining the use amount of coarse and fine aggregates by adopting a volumetric method or a mass method, and (7) carrying out trial mixing adjustment and determining the final mix proportion.

Description

Technical Field

[0001] This invention relates to the field of low-carbon building materials, specifically to a method for designing the mix proportions of geopolymer concrete. Background Technology

[0002] As one of the world's major carbon emission sources, the cement industry's carbon reduction efforts are crucial for mitigating global warming. Statistics show that global cement production accounts for approximately 7% of total CO2 emissions; in China, this figure reaches as high as 13% of the nation's total carbon emissions. Meanwhile, industrial production and urban construction generate large amounts of solid waste or byproducts annually, such as fly ash, coal gangue, and construction waste. If these solid wastes can be utilized to produce low-carbon cementitious materials that can replace cement, it is hoped that waste reduction and carbon emission reduction can be achieved simultaneously, creating a synergistic benefit of "reducing carbon emissions through waste," which is of great significance for promoting green and low-carbon development.

[0003] Against this backdrop, geopolymer concrete has garnered significant attention as a low-carbon alternative to cement concrete, not only reducing cement usage but also enabling large-scale disposal of solid waste. Geopolymers are low-carbon cementitious materials produced by reacting low-calcium silicate alumina raw materials such as fly ash and calcined clay with a small amount of alkali activators (such as NaOH and sodium silicate) under aqueous conditions. They can completely replace cement in concrete preparation. Geopolymer concrete exhibits mechanical properties comparable to ordinary cement concrete and demonstrates superior resistance to sulfate attack. For example, fly ash-based and calcined slag-based geopolymer concrete reduce carbon emissions by 40%–60% compared to ordinary silicate cement concrete and by 25%–50% compared to cement concrete with 30% auxiliary cementitious materials.

[0004] Designing the mix proportions of geopolymer concrete to meet its basic technical properties, such as workability and post-hardening mechanical properties, is a major technical challenge for its widespread adoption. It's important to note that geopolymer raw materials are widely available and their composition varies significantly. Even using the same activator and curing regime, concrete prepared from different sources of silica-alumina materials still exhibits significant performance differences, greatly increasing the complexity of mix design.

[0005] Given the complex and variable composition of geopolymer silica-alumina raw materials, preliminary experiments are indeed necessary before designing the mix proportions of geopolymer concrete with variable raw materials. Currently, there are two main types of preliminary experimental mix proportion design methods: one is through large-scale trial and error, even with the help of orthogonal experiments or response surface methodology to reduce the number of test groups, but due to the large number of variables, it is still time-consuming and labor-intensive (e.g., patent applications CN115656484A, CN118609716A, CN120364991A); the other is based on establishing mathematical models according to key influencing factors, drawing on the "water-cement ratio (or glue-water ratio) – strength" relationship in ordinary concrete, and determining design parameters through a small number of experiments. However, although patent CN111892343B introduces the concept of "cementing material strength grade" and controls strength through water-cement ratio, its assessment of cementing material strength grade still relies on multiple sets of mortar tests on activator modulus and dosage. In essence, this method controls three key factors: water-cement ratio, activator modulus, and dosage, and still requires a large number of experiments. Patent CN115650645B proposes to control compressive strength by adjusting the alkali-to-binder ratio. For different raw materials, a model of the relationship between strength and alkali-to-binder ratio can be established through pre-experimentation for mix design. However, the alkali-to-binder ratio does not take into account the influence of water consumption. When it is necessary to adjust the working performance, it is often necessary to adjust the water consumption. At this time, even if the same raw materials are used, it is necessary to conduct pre-experimentation again to determine the model of the relationship between strength and alkali-to-binder ratio under different water consumption, which is not efficient.

[0006] The current core challenge lies in reducing the number of pre-experimentation steps for geopolymer concrete mix design, achieving time-saving, labor-saving, and flexible adjustment of strength and workability. The key lies in identifying the core control factors affecting concrete performance. This allows for the establishment of a simple and reliable mathematical model through a small number of pre-experimentation steps, leading to the development of a geopolymer mix design method that is adaptable to different silica-alumina raw materials, requires fewer pre-experimentation steps, is easy to follow in engineering projects, and allows for flexible adjustment of strength and workability according to needs. This has significant theoretical and engineering value for the widespread application of geopolymer concrete. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes an innovative mix design method for geopolymer concrete. The core of this method lies in pointing out that not all cementitious materials contribute to strength, thus identifying a key parameter affecting the compressive strength of geopolymer concrete: the effective binder-to-water ratio (the ratio of effective cementitious material to water). Only five sets of preliminary experiments are needed to determine the linear relationship between compressive strength and the effective binder-to-water ratio, and simultaneously, the linear relationship between slump and water content. Compared to previous design methods, this significantly reduces the number of preliminary experiments, enabling efficient and precise mix design for target workability and strength, and allowing for flexible adjustment of strength and workability according to requirements.

[0008] This invention proposes a method for designing the mix proportions of geopolymer concrete, comprising:

[0009] Step 1, Preliminary Experiment to Determine Parameters: After determining the raw materials and curing conditions to be used, preliminary experiments are conducted to determine the parameters in Formula 1, which shows the relationship between slump and water consumption, and the parameters in Formula 2, which shows the relationship between compressive strength and effective glue ratio.

[0010] Formula 1,

[0011] In the formula, Slump of the geopolymer concrete, in mm; Water consumption per cubic meter of polymer concrete, kg / m³ 3 ; , , , , These are parameters to be determined in preliminary experiments; the slump should increase with increasing water usage, therefore, and Greater than 0;

[0012] Formula 2,

[0013] In the formula, The compressive strength of the geopolymer concrete is expressed in MPa. and These are parameters to be determined in preliminary experiments; compressive strength should increase with the increase of the effective glue ratio, therefore, Greater than 0; The effective cementitious material mass per cubic meter of polymer concrete, kg / m 3 For geopolymers, cementing materials include silica-alumina materials, as well as Na₂O and SiO₂ derived from alkali activators; however, not all cementing materials are useful. This only includes the mass of Na2O contained in the alkali activator per cubic meter of polymer concrete. Mass of effective SiO2 in cementitious materials and the effective Al2O3 mass in cementitious materials kg / m 3 ; Pick and 3.87 times The smaller value in; The mass of SiO2 provided per cubic meter of polymer concrete cementitious material, kg / m³ 3 ; The mass of SiO2 contained in each cubic meter of alkali activator for polymer concrete, in kg / m³ 3 ; The mass of silica-alumina material per cubic meter of polymer concrete, in kg / m³ 3; The mass of SiO2 provided by the silica-alumina material per cubic meter of polymer concrete, kg / m 3 ; The proportion of SiO2 in the silicon-aluminum material can be provided for the preliminary experimental determination; geopolymer gel Na n [(SiO2) q -AlO2-] n The molar ratio q of silicon to sodium in wH2O does not exceed 2, corresponding to a mass ratio of SiO2 to Na2O that does not exceed 3.87. This means that... More than 3.87 times At that time, excess SiO2 has no effect; geopolymer gel Na n [(SiO2) q -AlO2-] n The molar ratio of aluminum to sodium in wH2O is always 1, corresponding to a mass ratio of Al2O3 to Na2O of 1.65. This means that... More than 1.65 times At that time, the excess Al2O3 has no effect, therefore, Take 1.65 times To ensure that the silicon-aluminum material can provide sufficient Al2O3, Take at least 13 times ;

[0014] Preliminary experiments included slump tests under different water volumes to determine the parameters in Formula 1, and different silica-sodium ratios ( The compressive strength test under ( ) is used to determine the compressive strength in Formula 2. And compressive strength tests at different effective glue ratios to determine the value in Formula 2. and A recommended preliminary experimental method is as follows: fix... , ,as well as (set as) The silica-sodium ratio was increased from 0 to 2 in 0.5 increments (with water consumption also increasing accordingly). Five groups of geopolymer concrete were prepared and their slump and compressive strength were tested. The relationship between slump and water consumption was first analyzed using the attached graph. Figure 2 (For example) Determine the parameters of Formula 1, and then use the graph showing the reciprocal relationship between compressive strength and water consumption (see attached graph). Figure 3 (For example) Determine the formula in formula 2 Specifically, the compressive strength and the reciprocal of water consumption have a piecewise linear relationship. At that time, as the silicon-to-sodium ratio increases, the slope is... (Formula 3), but when the silicon-to-sodium ratio increases to make Then, the slope suddenly increased to (Formula 4), through the point of change of slope (here the horizontal coordinate is marked as...) Formula 5 can be used to determine this. There is a special case where silicon-aluminum materials alone can provide enough SiO2, that is... At this point, the relationship between compressive strength and the reciprocal of water usage can be described by a single linear function, namely Formula 4. Finally, the relationship between compressive strength and effective glue ratio is shown in the attached graph. Figure 4 (For example) Determine the formula in formula 2 and ;

[0015] Formula 3,

[0016] Formula 4,

[0017] Formula 5,

[0018] Step 2, determine water consumption: Use Formula 6, a variant of Formula 1, to determine the water consumption based on the target slump;

[0019] Formula 6,

[0020] Step 3, determine the effective cementitious material mass: Using Formula 7, a variation of Formula 2, determine the effective glue-to-water ratio based on the target compressive strength, and then determine the effective cementitious material mass based on the water usage. ;

[0021] Formula 7,

[0022] Step four: Determine the amounts of Na2O and SiO2 in the alkali activator, as well as the amount of silicon-aluminum material: To avoid wasting SiO2 in the alkali activator, the total amount of SiO2 provided by the cementitious material should not exceed 3.87 times the amount of Na2O and SiO2 in the cementitious material. ,Right now ,at this time ; Take 13 times Then there is Then preset For a value not greater than value Then there is The amounts of Na₂O and SiO₂ in the alkali activator, as well as the amount of silicon-aluminum material, are determined according to formulas 8, 9, and 10. There exists a special case where silicon-aluminum material alone can provide sufficient SiO₂. At this point, no alkaline activator is needed to provide SiO2. , , ;

[0023] Formula 8,

[0024] Formula 9,

[0025] Formula 10,

[0026] Step 5: Determine the amount of sodium silicate solution, the amount of sodium hydroxide solution, and their mass fraction: Based on the SiO2 content in the sodium silicate solution, determine the amount of sodium silicate solution using Formula 11; based on the Na2O and H2O content in the sodium silicate solution, determine the amount of sodium hydroxide solution and its mass fraction using Formulas 12 and 13.

[0027] Formula 11,

[0028] In the formula, The amount of sodium silicate solution used per cubic meter of geopolymer concrete, in kg / m³. 3 ; The percentage of SiO2 in the sodium silicate solution;

[0029] Formula 12,

[0030] In the formula, The amount of sodium hydroxide solution used per cubic meter of polymer concrete, in kg / m³. 3 ; The percentage of Na₂O in the sodium silicate solution; P H2O The percentage of H2O in the sodium silicate solution;

[0031] Formula 13,

[0032] In the formula, This represents the mass fraction of the sodium hydroxide solution used.

[0033] Step 6: Determine the amount of coarse and fine aggregates; set the sand ratio. (Water consumption not exceeding 100 kg / m³) 3 Take 0.3, and the water consumption should not be less than 160 kg / m³. 3 Take 0.4, water consumption is 100~160kg / m³ 3 (Interpolation), the amount of coarse and fine aggregates can be determined using formulas 14 and 15 based on the mass method, or using formulas 16 to 18 based on the volume method;

[0034] Formula 14,

[0035] Formula 15,

[0036] In the formula, The amount of fine aggregate used per cubic meter of polymer concrete, in kg / m³ 3 ; The amount of coarse aggregate per cubic meter of polymer concrete, in kg / m³ 3 ; The assumed mass of polymer concrete mixture per cubic meter, kg / m³ 3 2400 kg / m 3 ;

[0037] Formula 16,

[0038] Formula 17,

[0039] Formula 18,

[0040] In the formula, The volume percentage of aggregate in geopolymer concrete; Density of silicon-aluminum material, kg / m³ 3 ; The density of sodium hydroxide solution is kg / m³. 3 It can be accessed through Approximate values; Density of sodium silicate solution, kg / m³ 3 ; The air content of the geopolymer concrete can be taken as 1%; The density of fine aggregate is kg / m³. 3 ; This refers to the density of coarse aggregate, in kg / m³. 3 ;

[0041] Step 7: Determine the final mix proportion through trial mixing and adjustment: Conduct trial mixing using three different mix proportions, one of which is the previously determined baseline mix proportion. The effective glue ratio of the other two mix proportions is increased and decreased by 0.05 compared to the baseline, respectively. Water volume, as well as Keeping the sand ratio constant, the sand ratio is reduced and increased by 2% respectively compared to the baseline; if the workability of the mixture does not meet the requirements, the water content is increased by 10% while maintaining the effective glue-to-water ratio. as well as After remixing, once the workability is met, immediately pour test specimens and test their strength after curing. If all specimens fail to meet the strength requirements, increase the effective glue ratio by 0.1 while maintaining the same water content. as well as If the strength of any specimen meets the standard, the mix proportion corresponding to the minimum effective glue ratio that meets the strength requirement shall be selected as the final mix proportion.

[0042] Furthermore, the main oxide content of the silicon-aluminum raw materials used is not less than 30% for SiO2, not less than 15% for Al2O3, and not more than 10% for CaO; the alkali activator used is a mixed solution of sodium silicate solution and sodium hydroxide solution. The sodium silicate solution is either purchased directly as a finished product or prepared by dissolving solid sodium silicate in water. The sodium hydroxide solution is obtained by dissolving solid sodium hydroxide in water or by diluting concentrated sodium hydroxide solution. The sodium silicate solution and sodium hydroxide solution are mixed 24 hours before concrete pouring to obtain the alkali activator.

[0043] Furthermore, during the pre-experiment and trial mixing process, the same coarse and fine aggregates as those used in the actual project can be used for pouring. Alternatively, coarse and fine aggregates in a saturated surface-dry state can be used for concrete pouring. However, in this case, the water content needs to be adjusted accordingly based on the aggregate moisture content and water absorption rate during the actual mix design.

[0044] Furthermore, during the pre-experiment and trial mixing process, the slump test was conducted after mixing in the same manner as in the actual project. The concrete was then poured and cured to the specified age in the same manner as in the actual project before the compressive strength test was conducted.

[0045] Compared with the prior art, the advantages of the present invention are as follows: (1) For different silicon-aluminum raw materials, through a small number of pre-experiments proposed in this invention, a linear relationship model between compressive strength and effective glue ratio and a linear relationship model between slump and water consumption can be established, which can realize efficient and accurate mix design for target workability and strength performance, significantly reducing the number of pre-experiments required in previous design methods. (2) Without changing the raw materials and curing conditions, the mix ratio of concrete can be flexibly and quickly adjusted according to slump and strength requirements, effectively avoiding the waste of materials, time and manpower caused by repeated trial mixing. (3) The overall design concept is clear, practical and operable, easy to follow in engineering, and has the value of being promoted as a standard design method. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the geopolymer concrete mix design method of the present invention.

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 2 This is a graph showing the relationship between slump and water consumption obtained from a preliminary experiment in Embodiment 1 of the present invention.

[0049] Figure 3This is a graph showing the relationship between compressive strength and the reciprocal of water consumption obtained from the preliminary experiment in Embodiment 1 of the present invention.

[0050] Figure 4 This is a graph showing the relationship between compressive strength and effective glue ratio obtained from a preliminary experiment of Embodiment 1 of the present invention.

[0051] Figure 5 This is a graph showing the relationship between slump and water consumption obtained from a preliminary experiment in Embodiment 3 of the present invention.

[0052] Figure 6 This is a graph showing the relationship between compressive strength and the reciprocal of water consumption obtained from the preliminary experiment in Embodiment 3 of the present invention.

[0053] Figure 7 This is a graph showing the relationship between compressive strength and effective glue ratio obtained from a preliminary experiment of Embodiment 3 of the present invention. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, so that those skilled in the art can implement it with reference to the content of this document, and also so that they can better appreciate the advantages of this method: fewer pre-experiments, ease of engineering implementation, flexible adjustment of intensity and workability according to needs, and applicability to different silicon and aluminum raw materials. It should be understood that the described embodiments are only some embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] Example 1: Using the following raw materials and curing methods, the method proposed in this invention is used to design the mix proportion of geopolymer concrete to meet the engineering requirements of a slump of 100mm and a 28-day compressive strength of 40MPa: The silica-alumina raw material is calcined slag obtained from the calcination of engineering waste soil, with an apparent density of 2585kg / m³. 3 The SiO2 content is 62.55%, the Al2O3 content is 25.94%, and the CaO content is 0.98%. The sodium silicate solution used is a pre-prepared solution with Na2O, SiO2, and H2O contents of 8.83%, 27.64%, and 63.53%, respectively, and a density of 1370 kg / m³. 3 The sodium hydroxide solution is prepared by dissolving flake sodium hydroxide solid with a purity greater than 99% in tap water; the sodium silicate solution and sodium hydroxide solution are prepared and mixed 24 hours before concrete pouring; the fine aggregate is ordinary washed river sand with a particle size of less than 4.75 mm, a fineness modulus of 2.4, and an apparent density of 2611 kg / m³. 3 The coarse aggregate is continuously graded crushed stone with a particle size distribution ranging from 4.75 mm to 20 mm and an apparent density of 2715 kg / m³. 3The curing method is to cover the surface of the specimen with plastic film after casting for sealing and curing. After 24 hours, the mold is removed and sealing and curing continues for 28 days.

[0056] The specific implementation steps for mix design are as follows:

[0057] Step 1: Preliminary experiment to determine parameters: The amount of Na2O in the alkali activator is fixed at 30 kg / m³. 3 The amount of fixed silicon-aluminum material used is 390 kg / m³. 3 Fixed water-alkali ratio The ratio was set to 0.7, and the silica-sodium ratio was increased from 0 to 2 in increments of 0.5 (a total of 5 pre-experiment groups). The basic parameters of the five pre-experiment groups are shown in Table 1. The corresponding amounts and mass fractions of sodium silicate solution and sodium hydroxide solution were determined according to formulas 11-13. The sand ratio was set to 0.35, and the amounts of coarse and fine aggregates were determined according to formulas 16-18 based on the volumetric method. The mix proportions of the five pre-experiment groups are shown in Table 2.

[0058] Table 1 Basic parameters of the pre-experimental group

[0059]

[0060] Table 2. Mixture ratio of the pre-experimental group

[0061]

[0062] First, dry mix the silicon-aluminum material with coarse and fine aggregates for 2 minutes, then add the alkali activator and continue stirring for 2 minutes; after uniform mixing, test the slump and pour the specimens; cover the surface of the specimens with plastic film for sealing and curing, remove the mold after 24 hours and continue sealing and curing for 28 days, and then conduct compressive strength tests; the slump and compressive strength of each group are shown in Table 3.

[0063] Table 3 Slump and compressive strength of the pre-experimental group in Example 1

[0064] Pre-experimental group Slump (mm) Compressive strength (MPa) 1 40 45.2 2 130 40.1 3 210 35.6 4 230 30.2 5 250 23.5

[0065] From the appendix Figure 2 Formula 19 for the model of the relationship between slump and water consumption;

[0066] Formula 19,

[0067] From the appendix Figure 3 Determine the proportion of SiO2 in the silicon-aluminum material. When it is 0.201, hour, ;

[0068] From the appendix Figure 4 Formula 20 for determining the relationship between compressive strength and effective glue ratio;

[0069] Formula 20,

[0070] Step 2, determine water consumption: Using Formula 19, based on the target slump of 100mm, the water consumption is determined to be 127.9 kg / m³. 3 ;

[0071] Step 3, determine the effective cementitious material quality: Using formula 20, based on the target compressive strength of 40 MPa, determine the effective binder-to-water ratio to be 1.29, and based on the water consumption of 127.9 kg / m³. 3 The effective cementitious material mass was determined to be 164.4 kg / m³. 3 ;

[0072] Step 4: Determine the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material: Preset For a value not greater than The value is 0.8. Based on formulas 8, 9, and 10, the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material are determined to be 27.11 kg / m³. 3 21.69 kg / m 3 and 352.4 kg / m 3 ;

[0073] Step 5: Determine the dosage of sodium silicate solution, sodium hydroxide solution, and their mass fractions: Based on the SiO2 content of 27.64% in the sodium silicate solution, the dosage of sodium silicate solution is determined to be 78.47 kg / m³ using Formula 11. 3 Based on the Na₂O content of 8.83% and the H₂O content of 63.53% in the sodium silicate solution, the dosage of sodium hydroxide solution was determined to be 104.09 kg / m³ using formulas 12 and 13. 3 Its mass fraction is 25.02%, and its density is as follows: The approximate value is 1270 kg / m 3 ;

[0074] Step 6: Determine the amount of coarse and fine aggregates; the water consumption should not exceed 100 kg / m³. 3 Take 0.3, and the water consumption should not be less than 160 kg / m³. 3 Take 0.4, water consumption is 100~160kg / m³ 3 Interpolation yielded a sand ratio of 0.35; based on the volumetric method, formulas 16-18 determined the coarse and fine aggregate dosages to be 1243.4 kg / m³. 3 and 669.5 kg / m 3 ;

[0075] Step 7: Determine the final mix proportion through trial mixing and adjustment: Conduct trial mixing using three different mix proportions, one of which is the previously determined baseline mix proportion. The effective glue ratio of the other two mix proportions is increased and decreased by 0.05 compared to the baseline, respectively. Water volume, as well as The sand ratio remained unchanged, with the sand ratio decreasing and increasing by 2% respectively compared to the baseline. The three trial mixes are shown in Table 4.

[0076] Table 4. Three mix proportions for the trial mixing in Example 1

[0077] Trial mixing group Effective glue ratio Sand ratio <![CDATA[Coarse aggregate (kg / m 3 )]]> <![CDATA[Fine aggregate (kg / m 3 )]]> <![CDATA[Silicoaluminium material (kg / m 3 )]]> <![CDATA[Sodium silicate solution (kg / m 3 )]]> <![CDATA[Sodium hydroxide solution (kg / m 3 )]]> Mass fraction of sodium hydroxide solution (%) 1 1.29 0.35 1243.4 669.5 352.4 78.47 104.09 25.02 2 1.34 0.33 1270.9 626.0 367.51 81.82 103.07 26.35 3 1.24 0.37 1213.3 712.6 340.08 75.72 104.93 23.95

[0078] First, dry-mix the silicon-aluminum material with coarse and fine aggregates for 2 minutes, then add the alkali activator and continue stirring for another 2 minutes. After homogenization, test the slump and pour the mixture into specimens. Cover the specimens with plastic film for sealing and curing. After 24 hours, remove the mold and continue sealing and curing for 28 days, then conduct a compressive strength test. The slump and compressive strength of each group are shown in Table 5. The workability of each mixture meets the requirements, and the strength of the first and second groups meets the standards. Therefore, the first group with the minimum effective glue ratio that meets the strength requirements is selected as the final mix proportion.

[0079] Table 5. Slump and compressive strength of three mix proportions in Example 1.

[0080] Trial mixing group Effective glue ratio Slump (mm) Compressive strength (MPa) 1 1.29 110 40.6 2 1.34 105 44.3 3 1.24 100 37.5

[0081] Example 2: Using the raw materials and curing conditions in Example 1, design a geopolymer concrete mix proportion that meets the engineering requirements of a slump of 150mm and a 28-day compressive strength of 50MPa.

[0082] Obviously, without changing the raw materials and curing conditions, different mix proportions can be designed directly through steps two to seven without prior experiments to meet the target slump and strength of different concretes.

[0083] Step 2, determine water consumption: Using Formula 19, based on the target slump of 150mm, the water consumption is determined to be 139.8 kg / m³. 3 ;

[0084] Step 3, determine the effective cementitious material quality: Using formula 20, based on the target compressive strength of 50 MPa, determine the effective binder-to-water ratio to be 1.47, and based on the water consumption of 139.8 kg / m³. 3 The effective cementitious material mass was determined to be 205.9 kg / m³. 3 ;

[0085] Step 4: Determine the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material: Preset For a value not greater than The value is 0.8. Based on formulas 8, 9, and 10, the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material are determined to be 33.97 kg / m³. 3 27.18 kg / m 3 and 441.6 kg / m 3 ;

[0086] Step 5: Determine the dosage of sodium silicate solution, sodium hydroxide solution, and their mass fraction: Based on the SiO2 content of 27.64% in the sodium silicate solution, the dosage of sodium silicate solution is determined to be 98.32 kg / m³ using Formula 11. 3 Based on the Na₂O content of 8.83% and the H₂O content of 63.53% in the sodium silicate solution, the dosage of sodium hydroxide solution was determined to be 109.97 kg / m³ using formulas 12 and 13. 3 Its mass fraction is 29.67%, and its density is as follows: The approximate value is 1319 kg / m³ 3 ;

[0087] Step 6: Determine the amount of coarse and fine aggregates; the water consumption should not exceed 100 kg / m³. 3 Take 0.3, and the water consumption should not be less than 160 kg / m³. 3 Take 0.4, water consumption is 100~160kg / m³ 3 Interpolation yielded a sand ratio of 0.37; based on the volumetric method, formulas 16-18 determined the coarse and fine aggregate dosages to be 1119.3 kg / m³. 3 and 657.4 kg / m 3 ;

[0088] Step 7: Determine the final mix proportion through trial mixing and adjustment: Conduct trial mixing using three different mix proportions, one of which is the previously determined baseline mix proportion. The effective glue ratio of the other two mix proportions is increased and decreased by 0.05 compared to the baseline, respectively. Water volume, as well as The sand ratio remained unchanged, with the sand ratio decreasing and increasing by 2% respectively compared to the baseline. The three trial mixes are shown in Table 6.

[0089] Table 6. Three mix proportions for the trial mixing in Example 2

[0090] Trial mixing group Effective glue ratio Sand ratio <![CDATA[Coarse aggregate (kg / m 3 )]]> <![CDATA[Fine aggregate (kg / m 3 )]]> <![CDATA[Silicoaluminum material (kg / m 3 )]]> <![CDATA[Sodium silicate solution (kg / m 3 )]]> <![CDATA[Sodium hydroxide solution (kg / m 3 )]]> Mass fraction of sodium hydroxide solution (%) 1 1.47 0.37 1119.3 657.4 441.6 98.32 109.97 29.67 2 1.52 0.35 1145.0 616.5 455.7 101.45 109.02 30.88 3 1.42 0.39 1094.4 699.7 425.6 94.76 111.05 28.32

[0091] First, dry mix the silicon-aluminum material with coarse and fine aggregates for 2 minutes, then add the alkali activator and continue stirring for another 2 minutes. After homogenization, test the slump and pour the mixture into specimens. Cover the specimens with plastic film for sealing and curing. After 24 hours, remove the mold and continue sealing and curing for 28 days, then conduct a compressive strength test. The slump and compressive strength of each group are shown in Table 7. Since the workability and compressive strength of each mixture meet the requirements, the third group with the minimum effective glue ratio that meets the strength requirements is selected as the final mix proportion.

[0092] Table 7. Slump and compressive strength of three mix proportions in Example 2

[0093] Trial mixing group Effective glue ratio Slump (mm) Compressive strength (MPa) 1 1.47 150 53.2 2 1.52 155 57.8 3 1.42 160 50.2

[0094] Example 3: Using fly ash as a silicon-aluminum raw material, its apparent density is 2115 kg / m³. 3 The SiO2 content was 61.47%, the Al2O3 content was 15.53%, and the CaO content was 4.36%. Other materials were the same as in Example 1. After casting the specimens, the surface of the specimens was covered with a plastic film for sealing. After curing at 80°C for 24 hours, the mold was removed, and sealing and curing continued for 28 days. The design yielded a geopolymer concrete mix proportion that met the engineering requirements of a slump of 120mm and a 28-day compressive strength of 45MPa.

[0095] The raw materials and curing methods in this embodiment are different from those in Embodiment 1. Therefore, it is necessary to conduct preliminary experiments again for the raw materials and curing methods in this embodiment.

[0096] The specific implementation steps for mix design are as follows:

[0097] Step 1: Preliminary Experiment to Determine Parameters: The basic parameters and mix proportions of the preliminary experimental scheme are the same as in Example 1, as detailed in Tables 1 and 2. First, dry mix the silicon-aluminum material with coarse and fine aggregates for 2 minutes, then add the alkali activator and continue stirring for 2 minutes. After uniform mixing, test the slump and cast the specimens. Cover the specimen surface with a plastic film for sealing, cure at 80°C for 24 hours, then remove the mold and continue sealing and curing for 28 days before conducting the compressive strength test. The slump and compressive strength of each group are shown in Table 8.

[0098] Table 8 Slump and compressive strength of the pre-experimental group in Example 3

[0099] Pre-experimental group Slump (mm) Compressive strength (MPa) 1 60 60.7 2 160 55.1 3 230 50.5 4 240 45.6 5 255 37.9

[0100] From the appendix Figure 5 Formula 21 for determining the relationship between slump and water consumption;

[0101] Formula 21,

[0102] From the appendix Figure 6 Determine the proportion of SiO2 in the silicon-aluminum material. It is 0.194, when hour, ;

[0103] From the appendix Figure 7 Formula 22: Determine the relationship between compressive strength and effective glue ratio;

[0104] Formula 22,

[0105] Step 2, determine water consumption: Using Formula 21, based on the target slump of 120mm, the water consumption is determined to be 126.4 kg / m³. 3 ;

[0106] Step 3, determine the effective cementitious material quality: Using Formula 22, based on the target compressive strength of 45 MPa, determine the effective binder-to-water ratio to be 1.095, and based on the water consumption of 126.4 kg / m³. 3 The effective cementitious material mass was determined to be 138.4 kg / m³. 3 ;

[0107] Step 4: Determine the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material: Preset For a value not greater than The value is 0.8. Based on formulas 8, 9, and 10, the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material are determined to be 23.17 kg / m³. 3 18.54 kg / m 3 and 301.2 kg / m 3 ;

[0108] Step 5: Determine the dosage of sodium silicate solution, sodium hydroxide solution, and their mass fraction: Based on the SiO2 content of 27.64% in the sodium silicate solution, the dosage of sodium silicate solution is determined to be 67.06 kg / m³ using Formula 11. 3 Based on the Na₂O content of 8.83% and the H₂O content of 63.53% in the sodium silicate solution, the dosage of sodium hydroxide solution was determined to be 106.05 kg / m³ using formulas 12 and 13. 3 Its mass fraction is 20.99%, and its density is as follows: The approximate value is 1227 kg / m 3 ;

[0109] Step 6: Determine the amount of coarse and fine aggregates; the water consumption should not exceed 100 kg / m³. 3 Take 0.3, and the water consumption should not be less than 160 kg / m³. 3 Take 0.4, water consumption is 100~160kg / m³ 3Interpolation yielded a sand ratio of 0.34; based on the volumetric method, formulas 16-18 determined the coarse and fine aggregate dosages to be 1304.9 kg / m³. 3 and 672.2 kg / m 3 ;

[0110] Step 7: Determine the final mix proportion through trial mixing and adjustment: Conduct trial mixing using three different mix proportions, one of which is the previously determined baseline mix proportion. The effective glue ratio of the other two mix proportions is increased and decreased by 0.05 compared to the baseline, respectively. Water volume, as well as The sand ratio remained unchanged, with the sand ratio decreasing and increasing by 2% respectively compared to the baseline. The three trial mixes are shown in Table 9.

[0111] Table 9. Three mix proportions for the trial mixing in Example 3

[0112] Trial mixing group Effective glue ratio Sand ratio <![CDATA[Coarse aggregate (kg / m 3 )]]> <![CDATA[Fine aggregate (kg / m 3 )]]> <![CDATA[Silicoaluminum material (kg / m 3 ).]]> <![CDATA[Sodium silicate solution (kg / m 3 )]]> <![CDATA[Sodium hydroxide solution (kg / m 3 ).]]> Mass fraction of sodium hydroxide solution (%) 1 1.095 0.34 1304.9 672.2 301.2 67.06 106.05 20.99 2 1.145 0.32 1334.6 628.1 315.0 70.13 105.12 22.14 3 1.045 0.36 1274.5 716.9 287.6 64.02 106.97 19.86

[0113] First, dry mix the silicon-aluminum material with coarse and fine aggregates for 2 minutes, then add the alkali activator and continue stirring for another 2 minutes. After homogenization, test the slump and cast specimens. Cover the specimen surface with plastic film for sealing, cure at 80℃ for 24 hours, then remove the mold and continue sealing and curing for 28 days before conducting a compressive strength test. The slump and compressive strength of each group are shown in Table 10. The workability of each mixture group meets the requirements, and the strength of the second group meets the standard. Therefore, the second group with the minimum effective glue ratio that meets the strength requirement is selected as the final mix proportion.

[0114] Table 10 Slump and compressive strength of three mix proportions in Example 3

[0115] Trial mixing group Effective glue ratio Slump (mm) Compressive strength (MPa) 1 1.095 130 44.7 2 1.145 130 47.5 3 1.045 125 39.2

[0116] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for designing the mix proportions of geopolymer concrete, characterized in that, include: Step 1, Preliminary Experiment to Determine Parameters: After determining the raw materials and curing conditions to be used, preliminary experiments are conducted to determine the parameters in Formula 1, which shows the relationship between slump and water consumption, and the parameters in Formula 2, which shows the relationship between compressive strength and effective glue ratio. Formula 1, ; In the formula, Slump of the geopolymer concrete, in mm; Water consumption per cubic meter of polymer concrete, kg / m³ 3 ; , , , , These are the parameters to be determined in the preliminary experiment; Formula 2, ; In the formula, The compressive strength of the geopolymer concrete is expressed in MPa. and These are the parameters to be determined in the preliminary experiment; The effective cementitious material mass per cubic meter of polymer concrete, kg / m 3 This includes the mass of Na2O contained in the alkali activator per cubic meter of polymer concrete. Mass of effective SiO2 in cementitious materials and the effective Al2O3 mass in cementitious materials kg / m 3 ; Pick and 3.87 times The smaller value in; The mass of SiO2 provided per cubic meter of polymer concrete cementitious material, in kg / m³ 3 ; The mass of SiO2 contained in each cubic meter of alkali activator for polymer concrete, in kg / m³ 3 ; The mass of silica-alumina material per cubic meter of polymer concrete, in kg / m³ 3 ; The mass of SiO2 provided by the silica-alumina material per cubic meter of polymer concrete, kg / m 3 ; The proportion of SiO2 in the silicon-aluminum material can be provided for the silicon-aluminum material to be determined in the preliminary experiment; Take 1.65 times To ensure that the silicon-aluminum material can provide sufficient Al2O3, Take at least 13 times ; Preliminary experiments included slump tests under different water volumes to determine the parameters in Formula 1. The compressive strength test is used to determine the compressive strength in Formula 2. And compressive strength tests at different effective glue ratios to determine the value in Formula 2. and Specifically, as follows, fixed , ,as well as (set as) ),Will Water consumption increases from 0 to 2 in increments of 0.5, and the amount of water used also increases accordingly. As the slump and compressive strength of five groups of geopolymer concrete were prepared and tested, the parameters of Formula 1 were first determined by the relationship between slump and water consumption, and then the parameters in Formula 2 were determined by the relationship between compressive strength and the reciprocal of water consumption. Specifically, the compressive strength and the reciprocal of water consumption have a piecewise linear relationship. At that time, with The increase of the slope is (Formula 3), but when Increase to make Then, the slope suddenly increased to (Formula 4), through the point of change of slope (here the horizontal coordinate is marked as...) Formula 5 can be used to determine this. There is a special case where silicon-aluminum materials alone can provide enough SiO2, that is... At this point, the relationship between compressive strength and the reciprocal of water usage can be described by a single linear function, namely Formula 4. Finally, the relationship between compressive strength and effective glue ratio is determined by the graph in Formula 2. and ; Formula 3, ; Formula 4, ; Formula 5, ; Step 2, determine water consumption: Use Formula 6, a variant of Formula 1, to determine the water consumption based on the target slump; Formula 6, ; Step 3, determine the effective cementitious material mass: Using Formula 7, a variation of Formula 2, determine the effective glue-to-water ratio based on the target compressive strength, and then determine the effective cementitious material mass based on the water usage. ; Formula 7, ; Step four: Determine the amounts of Na2O and SiO2 in the alkali activator and the amount of silicon-aluminum material: To avoid wasting SiO2 in the alkali activator, the total amount of SiO2 provided by the cementitious material should not exceed 3.87 times the amount of Na2O and SiO2 in the cementitious material. ,Right now ,at this time ; Take 13 times Then there is Then preset For a value not greater than value Then there is The amounts of Na₂O and SiO₂ in the alkali activator, as well as the amount of silicon-aluminum material, are determined according to formulas 8, 9, and 10. There exists a special case where silicon-aluminum material alone can provide sufficient SiO₂. At this point, no alkaline activator is needed to provide SiO2. , , ; Formula 8, ; Formula 9, ; Formula 10, ; Step 5: Determine the amount of sodium silicate solution, sodium hydroxide solution and their mass fraction: Based on the SiO2 content in the sodium silicate solution, determine the amount of sodium silicate solution using Formula 11; Based on the proportions of Na₂O and H₂O in the sodium silicate solution, the amount and mass fraction of sodium hydroxide solution used are determined using formulas 12 and 13. Formula 11, ; In the formula, The amount of sodium silicate solution used per cubic meter of geopolymer concrete, in kg / m³. 3 ; The percentage of SiO2 in the sodium silicate solution; Formula 12, ; In the formula, The amount of sodium hydroxide solution used per cubic meter of polymer concrete, in kg / m³. 3 ; The percentage of Na₂O in the sodium silicate solution; P H2O The percentage of H2O in the sodium silicate solution; Formula 13, ; In the formula, This represents the mass fraction of the sodium hydroxide solution used. Step 6: Determine the amount of coarse and fine aggregates; set the sand ratio. Water consumption shall not exceed 100 kg / m³ 3 Take 0.3, and the water consumption should not be less than 160 kg / m³. 3 Take 0.4, water consumption is 100~160kg / m³ 3 Interpolation; determine the amount of coarse and fine aggregates using formulas 14 and 15 based on the mass method, or determine the amount of coarse and fine aggregates using formulas 16 to 18 based on the volume method; Formula 14, ; Formula 15, ; In the formula, The amount of fine aggregate per cubic meter of polymer concrete, in kg / m³ 3 ; The amount of coarse aggregate per cubic meter of polymer concrete, in kg / m³ 3 ; The assumed mass of polymer concrete mixture per cubic meter, kg / m³ 3 2400 kg / m 3 ; Formula 16, ; Formula 17, ; Formula 18, ; In the formula, The volume percentage of aggregate in geopolymer concrete; Density of silicon-aluminum material, kg / m³ 3 ; The density of sodium hydroxide solution is kg / m³. 3 It can be accessed through Approximate values; Density of sodium silicate solution, kg / m³ 3 ; The air content of the geopolymer concrete can be taken as 1%; The density of fine aggregate is kg / m³. 3 ; This refers to the density of coarse aggregate, in kg / m³. 3 ; Step 7: Determine the final mix proportion through trial mixing and adjustment: Conduct trial mixing using three different mix proportions, one of which is the previously determined baseline mix proportion. The effective glue ratio of the other two mix proportions is increased and decreased by 0.05 compared to the baseline, respectively. Water volume, as well as Keeping the sand ratio unchanged, the sand ratio is reduced and increased by 2% respectively compared to the baseline; if the workability of the mixture does not meet the requirements, the water content is increased by 10% while maintaining the effective glue ratio. as well as After remixing, once the workability is met, immediately pour test specimens and test their strength after curing. If all specimens fail to meet the strength requirements, increase the effective glue ratio by 0.1 while maintaining the same water content. as well as If the strength of any specimen meets the standard, the mix proportion corresponding to the minimum effective glue ratio that meets the strength requirement shall be selected as the final mix proportion.

2. The method for designing the mix proportion of geopolymer concrete according to claim 1, characterized in that: The main oxide content of the silicon-aluminum raw materials used is not less than 30% SiO2, not less than 15% Al2O3, and not more than 10% CaO. The alkali activator used is a mixed solution of sodium silicate solution and sodium hydroxide solution. The sodium silicate solution is either purchased directly as a finished product or prepared by dissolving solid sodium silicate in water. The sodium hydroxide solution is obtained by dissolving solid sodium hydroxide in water or diluting concentrated sodium hydroxide solution. The sodium silicate solution and sodium hydroxide solution are mixed 24 hours before concrete pouring to obtain the alkali activator.

3. The method for designing the mix proportion of geopolymer concrete according to claim 1, characterized in that: During the preliminary experiment and trial mixing, the same coarse and fine aggregates as those used in the actual project are used for pouring. Alternatively, coarse and fine aggregates in a saturated surface-dry state can be used for concrete pouring. However, in this case, the amount of water used in the actual mix design needs to be adjusted accordingly based on the moisture content and water absorption rate of the aggregates.

4. The method for designing the mix proportion of geopolymer concrete according to claim 1, characterized in that: During the preliminary experiment and trial mixing process, the slump test was conducted after mixing in the same way as the actual project. The concrete was then poured and cured to the specified age in the same way as the actual project before the compressive strength test was conducted.

Images