Quantitative evaluation method for reactive components and in-situ reaction degree of precursor in alkali excitation reaction

Abstract

The invention discloses a quantitative evaluation method for reactive components and in-situ reaction degree of a precursor in alkali excitation reaction, and aims to solve the problem that the reactive components and in-situ reaction degree of the existing precursor are difficult to accurately test and quantify. The quantitative evaluation method comprises the following steps: (1) calculating the total content of reactive components through a theoretical prediction model, (2) calculating the content of the reactive components through an alkali liquor dissolution test, and (3) calculating a result; 2, evaluating the in-situ reaction degree to obtain the in-situ reaction degree RD0; and 3, calculating each reactive component participating in the reaction in the precursor according to the in-situ reaction degree. The ideal assumption that the total oxide content or the amorphous phase content of the precursor is simply equivalent to the reactive component is avoided, so that the reaction behavior of the precursor under the real alkali excitation condition is reflected, and the accurate quantification of the effective components of the precursor under the in-situ reaction condition is realized; and a reliable basis is provided for collaborative utilization of the multi-source industrial solid waste precursor and accurate proportion design of an alkali-activated material.

Description

Technical Field

[0001] This invention belongs to the field of alkali-activated materials technology, and particularly relates to a quantitative evaluation method for the reactive components of a precursor and the degree of in-situ reaction in an alkali-activated reaction. Background Technology

[0002] In existing alkali-activated material systems, various industrial solid wastes such as fly ash, slag, red mud, steel slag, and biomass ash are widely used as precursors. These materials generally exhibit complex compositions, multiphase structures, and significant differences in activity. Existing technologies typically rely on chemical composition analysis (such as XRF) to obtain the equivalent amounts of each element as the "total chemical composition" or mineral composition analysis (such as XRD and microscopic observation) to obtain the "mineral phase composition," which are used to guide formulation design. However, these methods cannot accurately characterize the "reactive components" with reaction potential under alkali activation conditions, and they neglect the degree of in-situ reaction of these reactive components, thus failing to accurately quantify the "reactive components that actually undergo dissolution, rearrangement, and participate in gel formation," making it difficult to provide a direct basis for the refined formulation design of alkali-activated materials.

[0003] Another commonly used method is to indirectly evaluate precursor activity based on mechanical or cementitious properties. For example, this involves comparing precursors from different raw materials or under different process conditions through compressive strength development, activity index, and standard mortar mix design. These post-hoc methods are time-consuming and labor-intensive, heavily reliant on the specific proportions of the cementitious system, curing conditions, and specimen preparation process. The test results are often influenced by multiple factors, and their guidance for the design of alkali-activated material mixes is limited.

[0004] It is evident that there is currently a lack of a quantitative evaluation method for the types and contents of "reactive components participating in the reaction" in precursors, which leads to the design of alkali-activated materials relying heavily on experience, making it difficult to achieve comprehensive utilization of multi-source solid waste precursors. Summary of the Invention

[0005] The present invention aims to solve the problem that it is difficult to accurately test and quantify the reactive components of precursors and the degree of in-situ reaction in existing methods, and provides a quantitative evaluation method for the reactive components of precursors and the degree of in-situ reaction in alkaline-activated reactions.

[0006] The quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction of the present invention is implemented according to the following steps:

[0007] Step 1: Evaluation of Reactive Components

[0008] ① Calculate the total content of reactive components using a theoretical prediction model:

[0009] a. Grind the precursor to obtain the ground precursor;

[0010] b. Chemical analysis was performed on the ground precursor to obtain the total amount of equivalent oxides CaO (t-CaO, wt.%), SiO2 (t-SiO2, wt.%), and Al2O3 (t-Al2O3, wt.%).

[0011] c. Quantitative analysis was performed on the ground precursor. Dissolution in an alkaline solution at room temperature was used as the basis for determining the active and inert crystalline phases. The dissolved crystalline phase was considered the active crystalline phase, and the insoluble (or nearly insoluble) crystalline phase was considered the inert crystalline phase. The amorphous phase content (amor-CaO, wt.%), active crystalline phase content (crya-CaO, wt.%), and inert crystalline phase content (cryi-CaO, wt.%) of CaO oxide were obtained; the amorphous phase content (amor-SiO2, wt.%), active crystalline phase content (crya-SiO2, wt.%), and inert crystalline phase content (cryi-SiO2, wt.%) of SiO2 oxide were obtained; and the amorphous phase content (amor-Al2O3, wt.%), active crystalline phase content (crya-Al2O3, wt.%), and inert crystalline phase content (cryi-Al2O3, wt.%) of Al2O3 oxide were obtained.

[0012] d. The contents of each reactive component in the precursor obtained by the theoretical model method are calculated according to formulas (9) to (11):

[0013] (9)

[0014] (10)

[0015] (11)

[0016] in The content (wt.%) of reactive CaO component in the precursor of the representative theoretical model method. The content (wt.%) of reactive SiO2 component in the precursor of the representative theoretical model method. The content of reactive Al2O3 components in the precursor of the representative theoretical model method (wt.%).

[0017] ② Calculate the content of reactive components through an alkaline solution dissolution test:

[0018] e. Add the precursor with an initial mass of m0 to a NaOH solution to prepare a suspension. After stirring, perform solid-liquid separation to obtain a supernatant and a residual solid phase. Repeat the addition of NaOH solution to the residual solid phase and perform the solid-liquid separation process until the mass of the residual solid phase is constant. Calculate the mass fraction w of the reactive CaO component in the supernatant. Ca It can reflect the mass fraction w of the SiO2 component. Siand the mass fraction w of the reactant Al2O3 component Al (w) Ca +w Si +w Al =1);

[0019] f. Add the residual solid phase to pure water and perform ultrasonic cleaning to separate the cleaned residual solid phase.

[0020] g. Dry the residual solid phase after cleaning to constant weight. The mass of the precursor dissolved in the NaOH solution is Δm (i.e., the initial mass minus the mass of the residual solid phase). The total content of the reactive components of the precursor is then measured as RP. A ;

[0021]

[0022] Then, calculate the content of each reactive component in the precursor of the dissolution test according to equations (14) to (16):

[0023] (14)

[0024] (15)

[0025] (16)

[0026] In the formula, —Content of reactive CaO component in the precursor by the dissolution test (wt.%);

[0027] —Content of reactive SiO2 component in the precursor by dissolution test (wt.%);

[0028] —Content of reactive Al2O3 component in the precursor by dissolution test (wt.%);

[0029] ③ Result Calculation

[0030] The content of each reactive component in the precursor by the theoretical model method, the content of each reactive component in the precursor by the dissolution test method, or the average of the two are taken as the content of the reactive component in the precursor, namely the content of reactive CaO component a-CaO, the content of reactive SiO2 component a-SiO2, and the content of reactive Al2O3 component a-Al2O3 in the precursor, respectively.

[0031] Step 2: Assessment of the extent of in-situ reaction:

[0032] ① In the application scenario, the precursor and alkaline solution are mixed to construct an alkaline-activated reaction system, and the in-situ reaction degree RD0 under this reaction system is calculated by formulas (1), (2) and (3);

[0033] (1)

[0034] (2)

[0035] (3)

[0036] In the formula, RD0 represents the degree of in-situ reaction (%).

[0037] — Ideal response level (%)

[0038] α(T) — Reduction factor;

[0039] T — Reaction temperature (°C);

[0040] D 50 —Median particle size of precursor (μm);

[0041] C Na —The alkali content in the reaction system, i.e., Na2O / (Na2O+H2O) (wt.%).

[0042] t f —Reaction time (d) is the time corresponding to the inflection point (second derivative is 0) of the ultrasonic pulse velocity change with time in standard mortar (GB / T 17671-2021);

[0043] ② The precursor and alkaline solution are mixed to construct an alkaline-activated reaction system. Based on the particle size distribution of the precursor, the relationship curve between the degree of reaction RD and the reaction thickness δ is constructed by formula (4)~(5). According to the relationship curve, the degree of in-situ reaction RD0 under the alkaline-activated reaction system is determined by the in-situ reaction thickness δ0.

[0044] (4)

[0045] (5)

[0046] In the formula, RD represents the degree of reaction (%).

[0047] RD d — The degree of reactivity (%) of precursor particles with a diameter of d μm;

[0048] p d —The percentage of precursor particles with a diameter of d μm (%);

[0049] m DRP m RP — These are the total mass of the reactive components participating in the reaction and the total mass of the reactive components (kg), respectively.

[0050] V DRP V RP —These represent the total volume of the reactive components participating in the reaction and the total volume of the reactive components (m³). 3 );

[0051] d — Particle diameter (μm);

[0052] D—Maximum particle diameter (μm);

[0053] δ — reaction thickness (μm);

[0054] Step 3: Evaluation of Effective Components

[0055] Under alkaline-activated reaction system, the degree of in-situ reaction of the precursor, RD0, is determined by step ① or step ② of step two. The reactive components (effective components) participating in the reaction in the precursor are calculated according to the following formulas (17) to (19):

[0056] (17)

[0057] (18)

[0058] (19)

[0059] In the formula, a-CaO diss —Reactive CaO component (%) in the precursor participating in the reaction;

[0060] a-SiO2 diss —The percentage of reactive SiO2 components that participate in the reaction in the precursor;

[0061] a-Al2O3 diss —The percentage of reactive Al2O3 components in the precursor that participate in the reaction;

[0062] This provides a quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in alkaline-activated reactions.

[0063] Compared with the prior art, the quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in the alkali-activated reaction of the present invention has the following advantages:

[0064] To address the problem that existing technologies only provide the total oxide content and amorphous phase content of the precursor, or indirectly characterize the precursor's reactivity through mechanical properties, failing to reflect the actual components and their content participating in the reaction under alkaline activation conditions, this invention provides a quantitative evaluation method for the reactive components and in-situ reaction degree of the precursor in alkaline-activated reactions. It offers two methods for quantitatively evaluating the reactive components of the precursor in alkaline-activated reactions: theoretical prediction models and alkaline dissolution experiments. Furthermore, based on in-situ alkaline-activated reaction conditions (reaction temperature, reaction time, activator parameters, precursor-activator ratio), it achieves quantitative determination of the types and contents of effective components (reactive components participating in the reaction) in the precursor, providing a reliable basis for the design of alkaline-activated material formulations. Specific advantages are as follows:

[0065] (1) Existing technologies typically regard the total oxide content or amorphous phase oxide content of the precursor as the "potentially reactive component," implicitly assuming that "total oxide content ≈ total reactive component" or "amorphous phase oxide content ≈ total reactive component." This invention, through theoretical prediction models combined with alkaline dissolution experiments, distinguishes the "reactive components" that may participate in the reaction under alkaline activation conditions, fundamentally avoiding overly idealized assumptions and more closely reflecting the actual reaction behavior of the precursor in alkaline-activated reactions.

[0066] (2) The established theoretical prediction model or alkaline solution dissolution test has good applicability and complementarity. First, based on the physicochemical properties of the precursor, such as chemical composition, mineral composition, and amorphous phase content, the content of each reactive component (a-CaO', a-SiO2', a-Al2O3') is calculated and the total amount of reactive components (RP) is predicted. T Based on this, an alkaline solution dissolution test was conducted to obtain the total amount of reactive components (RP). A The contents of α-CaO'', α-SiO2'', and α-Al2O3'' were used as supplementary verification.

[0067] (3) Quantitative decomposition of reactive components has been achieved. Existing precursor activity evaluations mostly focus on macroscopic indicators and cannot distinguish the source and participation degree of reactive elements such as Ca, Si, and Al. This invention quantifies the content of reactive calcium oxide (a-CaO), reactive silicon oxide (a-SiO2), and reactive aluminum oxide (a-Al2O3), and accurately quantifies the dissolution behavior of precursors under alkaline-activated in-situ reaction conditions (in-situ reaction degree RD0, in-situ reaction thickness δ0) based on in-situ reaction degree assessment, thereby obtaining the effective component of the precursor (a-CaO) under in-situ reaction conditions. diss α-SiO2 diss α-Al2O3 dissThis provides more accurate basic parameters for designing the CaO-SiO2-Al2O3 molar ratio in alkali-activated materials and optimizing the type, modulus, and dosage of alkali activators. Attached Figure Description

[0068] Figure 1 This is a flowchart of the quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in the alkaline-activated reaction of the present invention.

[0069] Figure 2 This is a schematic diagram of the process for calculating the content of each reactive component in the precursor using two methods in step one of this invention;

[0070] Figure 3 This is a schematic diagram of the components in the precursor of the present invention;

[0071] Figure 4 This is a graph showing the relationship between the degree of reaction RD and the reaction thickness δ in step two of the embodiment. Detailed Implementation

[0072] Specific Implementation Method 1: The quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in the alkali-activated reaction of this implementation method is carried out according to the following steps:

[0073] Step 1: Evaluation of Reactive Components

[0074] ① Calculate the total content of reactive components using a theoretical prediction model:

[0075] a. Grind the precursor to obtain the ground precursor;

[0076] b. Chemical analysis was performed on the ground precursor to obtain the total amount of equivalent oxides CaO (t-CaO, wt.%), SiO2 (t-SiO2, wt.%), and Al2O3 (t-Al2O3, wt.%).

[0077] c. Quantitative analysis was performed on the ground precursor. Dissolution in an alkaline solution at room temperature was used as the basis for determining the active and inert crystalline phases. The dissolved crystalline phase was considered the active crystalline phase, and the insoluble (or nearly insoluble) crystalline phase was considered the inert crystalline phase. The amorphous phase content (amor-CaO, wt.%), active crystalline phase content (crya-CaO, wt.%), and inert crystalline phase content (cryi-CaO, wt.%) of CaO oxide were obtained; the amorphous phase content (amor-SiO2, wt.%), active crystalline phase content (crya-SiO2, wt.%), and inert crystalline phase content (cryi-SiO2, wt.%) of SiO2 oxide were obtained; and the amorphous phase content (amor-Al2O3, wt.%), active crystalline phase content (crya-Al2O3, wt.%), and inert crystalline phase content (cryi-Al2O3, wt.%) of Al2O3 oxide were obtained.

[0078] d. The contents of each reactive component in the precursor obtained by the theoretical model method are calculated according to formulas (9) to (11):

[0079] (9)

[0080] (10)

[0081] (11)

[0082] in The content (wt.%) of reactive CaO component in the precursor of the representative theoretical model method. The content (wt.%) of reactive SiO2 component in the precursor of the representative theoretical model method. The content of reactive Al2O3 components in the precursor of the representative theoretical model method (wt.%).

[0083] ② Calculate the content of reactive components through an alkaline solution dissolution test:

[0084] e. Add the precursor with an initial mass of m0 to a NaOH solution to prepare a suspension. After stirring, perform solid-liquid separation to obtain a supernatant and a residual solid phase. Repeat the addition of NaOH solution to the residual solid phase and perform the solid-liquid separation process until the mass of the residual solid phase is constant. Calculate the mass fraction w of the reactive CaO component in the supernatant. Ca It can reflect the mass fraction w of the SiO2 component. Si and the mass fraction w of the reactant Al2O3 component Al (w) Ca +w Si +w Al =1);

[0085] f. Add the residual solid phase to pure water and perform ultrasonic cleaning to separate the cleaned residual solid phase.

[0086] g. Dry the residual solid phase after cleaning to constant weight. The mass of the precursor dissolved in the NaOH solution is Δm (i.e., the initial mass minus the mass of the residual solid phase). The total content of the reactive components of the precursor is then measured as RP. A ;

[0087]

[0088] Then, calculate the content of each reactive component in the precursor of the dissolution test according to equations (14) to (16):

[0089] (14)

[0090] (15)

[0091] (16)

[0092] In the formula, —Content of reactive CaO component in the precursor by the dissolution test (wt.%);

[0093] —Content of reactive SiO2 component in the precursor by dissolution test (wt.%);

[0094] —Content of reactive Al2O3 component in the precursor by dissolution test (wt.%);

[0095] ③ Result Calculation

[0096] The content of each reactive component in the precursor by the theoretical model method, the content of each reactive component in the precursor by the dissolution test method, or the average of the two are taken as the content of the reactive component in the precursor, namely the content of reactive CaO component a-CaO, the content of reactive SiO2 component a-SiO2, and the content of reactive Al2O3 component a-Al2O3 in the precursor, respectively.

[0097] Step 2: Assessment of the extent of in-situ reaction:

[0098] ① In the application scenario, the precursor and alkaline solution are mixed to construct an alkaline-activated reaction system, and the in-situ reaction degree RD0 under this reaction system is calculated by formulas (1), (2) and (3);

[0099] (1)

[0100] (2)

[0101] (3)

[0102] In the formula, RD0 represents the degree of in-situ reaction (%).

[0103] — Ideal response level (%)

[0104] α(T) — Reduction factor;

[0105] T — Reaction temperature (°C);

[0106] D 50 —Median particle size of precursor (μm);

[0107] C Na —The alkali content in the reaction system, i.e., Na2O / (Na2O+H2O) (wt.%).

[0108] t f —Reaction time (d) is the time corresponding to the inflection point (second derivative is 0) of the ultrasonic pulse velocity change with time in standard mortar (GB / T 17671-2021);

[0109] ② The precursor and alkaline solution are mixed to construct an alkaline-activated reaction system. Based on the particle size distribution of the precursor, the relationship curve between the degree of reaction RD and the reaction thickness δ is constructed by formula (4)~(5). According to the relationship curve, the degree of in-situ reaction RD0 under the alkaline-activated reaction system is determined by the in-situ reaction thickness δ0 (the in-situ reaction thickness δ0 can be obtained by referring to existing data based on the alkaline solution parameters).

[0110] (4)

[0111] (5)

[0112] In the formula, RD represents the degree of reaction (%).

[0113] RD d — The degree of reactivity (%) of precursor particles with a diameter of d μm;

[0114] p d —The percentage of precursor particles with a diameter of d μm (%);

[0115] m DRP m RP — These are the total mass of the reactive components participating in the reaction and the total mass of the reactive components (kg), respectively.

[0116] V DRP V RP—These represent the total volume of the reactive components participating in the reaction and the total volume of the reactive components (m³). 3 );

[0117] d — Particle diameter (μm);

[0118] D—Maximum particle diameter (μm);

[0119] δ — reaction thickness (μm);

[0120] Step 3: Evaluation of Effective Components

[0121] Under alkaline-activated reaction system, the degree of in-situ reaction of the precursor, RD0, is determined by step ① or step ② of step two. The reactive components (effective components) participating in the reaction in the precursor are calculated according to the following formulas (17) to (19):

[0122] (17)

[0123] (18)

[0124] (19)

[0125] In the formula, a-CaO diss —Reactive CaO component (%) in the precursor participating in the reaction;

[0126] a-SiO2 diss —The percentage of reactive SiO2 components that participate in the reaction in the precursor;

[0127] a-Al2O3 diss —The percentage of reactive Al2O3 components in the precursor that participate in the reaction;

[0128] This provides a quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in alkaline-activated reactions.

[0129] In step two of this embodiment, the parameters involved in calculating the degree of in-situ reaction of the precursor in the alkaline-activated reaction are subject to the following constraints:

[0130] ①0≤RD0≤RD≤100%;

[0131] ②0 <D 50 <200 μm, , ;

[0132] ③0≤C Na <60%, , ;

[0133] ④20℃≤T≤100℃ ;

[0134] ⑤t f ≥0 min, , , ;

[0135] ⑥0≤α(T) ≤1.

[0136] This embodiment of the quantitative evaluation method for the reactive components and in-situ reaction degree of the precursor in the alkali-activated reaction avoids the idealized assumption of simply equating the total oxide content or amorphous phase content of the precursor with the reactive components. It reflects the reaction behavior of the precursor under real alkali-activated conditions, realizing a refined decomposition from macroscopic activity evaluation to "effective Ca, Si, and Al key components". It provides unified and quantifiable basic parameters for determining the CaO-SiO2-Al2O3 molar ratio of the alkali-activated material system and for optimizing the type, modulus, and dosage of alkali activators. It provides a reliable basis for the synergistic utilization of precursors from multi-source industrial solid waste and the precise proportioning design of alkali-activated materials, and has good social and economic value.

[0137] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the precursor is one or more mixtures of fly ash, slag, red mud, steel slag, and biomass ash.

[0138] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the precursor is ground to <10 μm in step a.

[0139] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that step b involves X-ray fluorescence spectroscopy (XRF) analysis of the milled precursor.

[0140] Specific Implementation Method 5: This implementation method differs from one of the specific implementation methods 1 to 3 in that step c involves quantitative analysis of the precursor using an X-ray diffractometer (XRD).

[0141] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One through Five in that the predicted total content RP of the precursor in step d is... T The formula for calculating (wt.%) is as follows:

[0142]

[0143] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the molar concentration of the NaOH solution in step e is 12 mol / L.

[0144] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that step e uses inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) to test the mass fraction of reactive CaO in the supernatant. Ca It can reflect the mass fraction w of SiO2 Si and the mass fraction w of reactant Al2O3 Al .

[0145] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the drying temperature in step g is 250°C.

[0146] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that step three divides the reactive components in the precursor into individual reactive components α-CaO that participate in the reaction. diss α-SiO2 diss and a-Al2O3 diss and unreactable reactive component α-CaO und α-SiO2 und and a-Al2O3 und .

[0147] Example: The quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction of this example is implemented according to the following steps:

[0148] Step 1: Evaluation of Reactive Components

[0149] ① Calculate the total content of reactive components using a theoretical prediction model:

[0150] a. Grind the low-calcium fly ash precursor to submicron size while preserving the crystal lattice characteristics of the sample to obtain the ground precursor.

[0151] b. X-ray fluorescence spectroscopy (XRF) analysis was performed on the ground precursor to obtain the total amount of equivalent oxides CaO t-CaO (wt.%), SiO2 t-SiO2 (wt.%) and Al2O3 t-Al2O3 (wt.%).

[0152] c. Quantitative analysis of the ground precursor was performed using X-ray diffraction (XRD). Dissolution in an alkaline solution at room temperature was used as the basis for determining the active and inert crystalline phases. The dissolved crystalline phase was considered the active crystalline phase, and the insoluble (or nearly insoluble) crystalline phase was considered the inert crystalline phase. The amorphous phase content of CaO (amor-CaO wt.%), the active crystalline phase content of Crya-CaO (wt.%), and the inert crystalline phase content of Cryi-CaO (wt.%) were obtained; the amorphous phase content of SiO2 (amor-SiO2 wt.%), the active crystalline phase content of Crya-SiO2 (wt.%), and the inert crystalline phase content of Cryi-SiO2 (wt.%) were obtained; and the amorphous phase content of Al2O3 (amor-Al2O3 wt.%), the active crystalline phase content of Crya-Al2O3 (wt.%), and the inert crystalline phase content of Cryi-Al2O3 (wt.%) were obtained. The results are shown in Table 1.

[0153] Table 1. Content of Ca-Si-Al components in the precursor

[0154]

[0155] d. The content of each component satisfies the relationship described in equations (6) to (8):

[0156] (6)

[0157] (7)

[0158] (8)

[0159] The contents of each reactive component in the precursor obtained by the theoretical model method are calculated according to equations (9) to (11):

[0160] (9)

[0161] (10)

[0162] (11)

[0163] in The content (wt.%) of reactive CaO component in the precursor of the representative theoretical model method. The content (wt.%) of reactive SiO2 component in the precursor of the representative theoretical model method. The content of reactive Al2O3 components in the precursor of the representative theoretical model method (wt.%).

[0164] The total content of reactive components is calculated using equation (12):

[0165] (12)

[0166] In this embodiment, XRF analysis revealed t-CaO, t-SiO2, and t-Al2O3 contents of 1.9 wt.%, 52.5 wt.%, and 29.1 wt.%, respectively. XRD analysis revealed the mineral phases as mullite 3Al2O3·2SiO2 (24.6 wt.%), quartz SiO2 (2.9 wt.%), and magnetite (Fe2O3). 2+ (Fe) 3+ The composition consisted of α-CaO (0.7 wt.%), hematite Fe2O3 (0.1 wt.%), and amorphous phase (71.8 wt.%). Given the chemical reactivity of mullite, quartz, magnetite, and hematite, these were all classified as inert crystalline phases. The calculated contents of each reactive component (α-CaO, α-SiO2, α-Al2O3) were 1.9 wt.%, 42.6 wt.%, and 11.4 wt.%, respectively. The predicted total content of reactive components was RP. T It was 55.9 wt.%.

[0167] ② Calculate the content of reactive components through an alkaline solution dissolution test:

[0168] e. Add 1g (accurate to 0.0001g, denoted as m0) of low-calcium fly ash precursor (particle size less than 200 μm) to a 12M NaOH solution, prepare a suspension with a liquid-to-solid ratio of 50g:1g, and dissolve it by magnetic stirring at 25℃ for 24 hours. Centrifuge to separate the solid and liquid phases, obtaining the supernatant and the residual solid phase. Repeat the addition of NaOH solution to the residual solid phase and perform solid-liquid separation, performing 6 dissolution cycles until the total content of the reactive components of the precursor no longer changes. Calculate the mass fraction w of the reactive CaO component in the supernatant. Ca It can reflect the mass fraction w of the SiO2 component. Si and the mass fraction w of the reactant Al2O3 component Al (w) Ca +w Si +w Al =1);

[0169] f. Add the residual solid phase to pure water and perform ultrasonic cleaning to separate the cleaned residual solid phase.

[0170] g. Dry the residual solid phase after cleaning to constant weight. The mass of the precursor dissolved in the NaOH solution is Δm (i.e., the initial mass minus the mass of the residual solid phase). The total content of the reactive components of the precursor is then measured as RP. A ;

[0171]

[0172] Then, calculate the content of each reactive component in the precursor of the dissolution test according to equations (14) to (16):

[0173] (14)

[0174] (15)

[0175] (16)

[0176] In the formula —Content of reactive CaO component in the precursor by the dissolution test (wt.%);

[0177] —Content of reactive SiO2 component in the precursor by dissolution test (wt.%);

[0178] —Content of reactive Al2O3 component in the precursor by dissolution test (wt.%);

[0179] In this embodiment, the total content (RP) of the reactive components of the precursor was calculated. A The content was 59.3 wt.%; based on the cumulative content of dissolved elements, the mass fractions w of reactive CaO, SiO2, and Al2O3 were obtained. Ca w Si w Al The concentrations were 0.04, 0.74, and 0.22, respectively, and the contents of each reactive component (a-CaO, a-SiO2, a-Al2O3) were 2.4 wt.%, 43.9 wt.%, and 13.0 wt.%, respectively.

[0180] ③ Result Calculation

[0181] The average content of each reactive component in the precursor obtained by the theoretical model method and the precursor obtained by the dissolution test method was taken as the reactive component content of the precursor. The contents of each reactive component (a-CaO, a-SiO2, a-Al2O3) in this low-calcium fly ash sample were 2.1 wt.%, 43.2 wt.%, and 12.2 wt.%, respectively, and the total reactive component content (RP) was 57.5 wt.%.

[0182] Step 2: Assessment of the extent of in-situ reaction:

[0183] ① In the application scenario, the precursor and alkaline solution are mixed to construct an alkaline-activated reaction system, and the in-situ reaction degree RD0 under this reaction system is calculated by formulas (1), (2) and (3);

[0184] (1)

[0185] (2)

[0186] (3)

[0187] In the formula, RD0 represents the degree of in-situ reaction (%).

[0188] — Ideal response level (%)

[0189] α(T) — Reduction factor;

[0190] T — Reaction temperature (°C);

[0191] D 50 —Median particle size of precursor (μm);

[0192] C Na —The alkali content in the reaction system, i.e., Na2O / (Na2O+H2O) (wt.%).

[0193] t f —Reaction time (d) is the time corresponding to the inflection point (second derivative is 0) of the ultrasonic pulse velocity change with time in standard mortar (GB / T 17671-2021);

[0194] ② A base-activated reaction system is constructed by mixing the precursor and an alkaline solution. Based on the particle size distribution of the precursor, the relationship curve between the degree of reaction RD and the reaction thickness δ is constructed using equations (4) and (5). Figure 4 As shown in the figure, the in-situ reaction degree RD0 under the base-activated reaction system can be determined by using the in-situ reaction thickness δ0;

[0195] (4)

[0196] (5)

[0197] In the formula, RD represents the degree of reaction (%).

[0198] RD d — The degree of reactivity (%) of precursor particles with a diameter of d μm;

[0199] p d —The percentage of precursor particles with a diameter of d μm (%);

[0200] m DRP m RP — These are the total mass of the reactive components participating in the reaction and the total mass of the reactive components (kg), respectively.

[0201] VDRP V RP —These represent the total volume of the reactive components participating in the reaction and the total volume of the reactive components (m³). 3 );

[0202] d — Particle diameter (μm);

[0203] D—Maximum particle diameter (μm), D=3500 μm;

[0204] δ — reaction thickness (μm);

[0205] Step 3: Evaluation of Effective Components

[0206] Under alkaline-activated reaction system, the degree of in-situ reaction of the precursor, RD0, is determined by step ① or step ② of step two. The reactive components (effective components) participating in the reaction in the precursor are calculated according to the following formulas (17) to (19):

[0207] (17)

[0208] (18)

[0209] (19)

[0210] In the formula, a-CaO diss —Reactive CaO component (%) in the precursor participating in the reaction;

[0211] a-SiO2 diss —The percentage of reactive SiO2 components that participate in the reaction in the precursor;

[0212] a-Al2O3 diss —The percentage of reactive Al2O3 components in the precursor that participate in the reaction;

[0213] This provides a quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in alkaline-activated reactions.

[0214] The extent of in-situ reaction and effective components in this embodiment:

[0215] Precursor: Using the aforementioned fly ash, step one yielded α-CaO = 2.1 wt.%, α-SiO2 = 43.2 wt.%, α-Al2O3 = 12.2 wt.%, and D. 50 =23.8 μm, SSA=1.96 m 2 / g.

[0216] Activator: Na2O·1.5SiO2 (H2O=60 wt.%) solution was used, in which the mass percentages of each component were Na2O=16.3 wt.%, SiO2=23.7 wt.%, and H2O=60.0 wt.%.

[0217] Reaction conditions: Temperature T = 20℃, activator-precursor ratio = 0.75, final setting time t f =12.3 d.

[0218] From equations (1) to (3), the ideal reaction degree RD = 87.3%, the reduction coefficient α(20) = 0.48, and the in-situ reaction degree RD0 = 41.9%. Combining the particle size distribution characteristics of the precursor, the in-situ reaction thickness δ = 1.6 μm is obtained from equations (4) to (5). Furthermore, the effective components of the precursor under the current activator and reaction conditions, i.e., the reactive components participating in the reaction, α-CaO, are calculated from equations (17) to (19). diss =0.88 wt.%, a-SiO2 diss =18.10 wt.%, α-Al2O3 diss =5.11 wt.%.

[0219] In this embodiment, the reactive components (a-CaO, a-SiO2, a-Al2O3) in the precursor are classified as effective components, namely, the reactive components (a-CaO) that participate in the reaction. diss α-SiO2 diss α-Al2O3 diss ) and ineffective components, i.e., reactive components that did not participate in the reaction (α-CaO) und α-SiO2 und α-Al2O3 und The content of each component in the precursor is as follows: Figure 3 As shown, the effective component (a-CaO) is... diss α-SiO2 diss α-Al2O3 diss By combining the parameters of the base activator with those of the base activator, the types and contents of reaction products can be predicted more accurately.

[0220] In summary, this invention provides a quantitative evaluation method for the reactive components and in-situ reaction degree of a precursor in an alkaline-activated reaction: on the one hand, by combining in-situ reaction conditions, the in-situ reaction degree and in-situ reaction thickness of the precursor under specified reaction conditions are quantitatively evaluated; on the other hand, by combining a theoretical prediction model with an alkaline dissolution test, the contents of reactive calcium oxide, reactive silicon oxide, and reactive aluminum oxide in the precursor are quantitatively characterized, and the total amount of reactive components is calculated accordingly; by combining the in-situ reaction degree and reactive components, the reactive components participating in the reaction, i.e., the effective components, are obtained. The method avoids the idealized assumption that the total oxide content or amorphous phase content of the precursor is simply equated with the reactive components. Instead, it reflects the reaction behavior of the precursor under real alkaline activation conditions, realizing a refined decomposition from macroscopic activity evaluation to "effective Ca, Si, and Al key components". It provides unified and quantifiable basic parameters for determining the CaO-SiO2-Al2O3 molar ratio of the alkaline activated material system and for optimizing the type, modulus, and dosage of alkaline activators. It provides a reliable basis for the synergistic utilization of precursors from multi-source industrial solid waste and the precise proportioning design of alkaline activated materials, and has good social and economic value.

Claims

1. A method for quantitatively evaluating the reactive components of a precursor and the degree of in-situ reaction in a base-activated reaction, characterized in that... The quantitative evaluation method is implemented according to the following steps: Step 1: Evaluation of Reactive Components ① Calculate the total content of reactive components using a theoretical prediction model: a. Grind the precursor to obtain the ground precursor; b. Chemical analysis was performed on the ground precursor to obtain the total amount of equivalent oxides CaO (t-CaO), SiO2 (t-SiO2), and Al2O3 (t-Al2O3). c. Quantitative analysis was performed on the ground precursor. Dissolution in an alkaline solution at room temperature was used as the basis for determining the active and inert crystalline phases. The dissolved crystalline phase was considered the active crystalline phase, and the undissolved crystalline phase was considered the inert crystalline phase. The amorphous phase content (amor-CaO), active crystalline phase content (crya-CaO), and inert crystalline phase content (cryi-CaO) of CaO were obtained respectively; the amorphous phase content (amor-SiO2), active crystalline phase content (crya-SiO2), and inert crystalline phase content (cryi-SiO2) of SiO2 were obtained respectively; and the amorphous phase content (amor-Al2O3), active crystalline phase content (crya-Al2O3), and inert crystalline phase content (cryi-Al2O3) of Al2O3 were obtained respectively. d. The contents of each reactive component in the precursor obtained by the theoretical model method are calculated according to formulas (9) to (11): （9） （10） （11） in The content of reactive CaO components in the precursor represented by the theoretical model method. The content of reactive SiO2 components in the precursor represented by the theoretical model method. The content of reactive Al2O3 components in the precursor of the representative theoretical model method; ② Calculate the content of reactive components through an alkaline solution dissolution test: e. Add the precursor with an initial mass of m0 to a NaOH solution to prepare a suspension. After stirring, perform solid-liquid separation to obtain a supernatant and a residual solid phase. Repeat the addition of NaOH solution to the residual solid phase and perform the solid-liquid separation process until the mass of the residual solid phase is constant. Calculate the mass fraction w of the reactive CaO component in the supernatant. Ca It can reflect the mass fraction w of the SiO2 component. Si and the mass fraction w of the reactant Al2O3 component Al ; f. Add the residual solid phase to pure water and perform ultrasonic cleaning to separate the cleaned residual solid phase. g. Dry the residual solid phase after cleaning to constant weight. If the mass of the precursor dissolved in the NaOH solution is Δm, then the total content of the reactive components of the precursor is RP. A ; Then, calculate the content of each reactive component in the precursor of the dissolution test according to equations (14) to (16): （14） （15） （16） In the formula —The content of reactive CaO components in the precursor by the dissolution test; —The content of reactive SiO2 components in the precursor by the dissolution test; —The content of reactive Al2O3 components in the precursor by the dissolution test; ③ Result Calculation The content of each reactive component in the precursor by the theoretical model method, the content of each reactive component in the precursor by the dissolution test method, or the average of the two are taken as the content of the reactive component in the precursor, namely the content of reactive CaO component a-CaO, the content of reactive SiO2 component a-SiO2, and the content of reactive Al2O3 component a-Al2O3 in the precursor, respectively. Step 2: Assessment of the extent of in-situ reaction: ① In the application scenario, the precursor and alkaline solution are mixed to construct an alkaline-activated reaction system, and the in-situ reaction degree RD0 under this reaction system is calculated by formulas (1), (2) and (3); （1） （2） （3） In the formula, RD0 represents the degree of in-situ reaction; — Ideal response level; α(T) — Reduction factor; T—Reaction temperature (°C); D 50 —Median particle size of the precursor (μm); C Na —The alkali content in the reaction system is wt.%, i.e., Na2O / (Na2O+H2O); t f —Reaction time d; ② The precursor and alkaline solution are mixed to construct an alkaline-activated reaction system. Based on the particle size distribution of the precursor, the relationship curve between the degree of reaction RD and the reaction thickness δ is constructed by formula (4)~(5). The degree of in-situ reaction RD0 under the alkaline-activated reaction system is then determined by the in-situ reaction thickness δ0. （4） （5） In the formula, RD represents the degree of reaction; RD d — The degree of reactivity of precursor particles with a diameter of d μm; p d —The proportion of precursor particles with a diameter of d μm; m DRP m RP —These represent the total mass of the reactive components participating in the reaction and the total mass of the reactive components (kg), respectively. V DRP V RP — These represent the total volume of the reactive components participating in the reaction and the total volume m of the reactive components, respectively. 3 ; d — particle diameter in μm; D—Maximum particle diameter in μm; δ — reaction thickness in μm; Step 3: Evaluation of Effective Components In the alkaline-activated reaction system, the degree of in-situ reaction of the precursor, RD0, is determined by step ① or step ② of step two. The reactive components in the precursor that participate in the reaction are calculated according to the following formulas (17) to (19): （17） （18） （19） In the formula, a-CaO diss —The percentage of reactive CaO components in the precursor that participate in the reaction. a-SiO2 diss —Reactive SiO2 components participating in the reaction in the precursor; a-Al2O3 diss —Reactive Al2O3 components in the precursor that participate in the reaction; This provides a quantitative evaluation method for the reactive components of the precursor and the degree of in-situ reaction in alkaline-activated reactions.

2. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... The precursor is one or more mixtures of fly ash, slag, red mud, steel slag and biomass ash.

3. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... In step a, the precursor is ground to <10 μm.

4. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... In step b, the milled precursor is subjected to X-ray fluorescence spectroscopy analysis.

5. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... In step c, the precursor is quantitatively analyzed using an X-ray diffractometer.

6. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... Predicted total content RP of the precursor in step d T The calculation formula is as follows: 。 7. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... In step e, the molar concentration of the NaOH solution is 12 mol / L.

8. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in the base-activated reaction according to claim 1, characterized in that... In step e, inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) is used to determine the mass fraction w of reactive CaO in the supernatant. Ca It can reflect the mass fraction w of SiO2 Si and the mass fraction w of reactant Al2O3 Al .

9. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in a base-activated reaction according to claim 1, characterized in that... The drying temperature in step g is 250℃.

10. The method for quantitatively evaluating the reactive components of the precursor and the degree of in-situ reaction in a base-activated reaction according to claim 1, characterized in that... Step 3 involves dividing the reactive components in the precursor into individual reactive components, α-CaO, that participate in the reaction. diss α-SiO2 diss and a-Al2O3 diss and unreactable reactive component α-CaO und α-SiO2 und and a-Al2O3 und .

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